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Car won't start - suspect PassKey/VATS??

8K views 32 replies 2 participants last post by  Alchemist 
#1 ·
My 95SS has the Z28 cluster mod, so no Passkey/Vats warning light. I went to get gas last night and car wouldn't start back up. Towed it home and did the following checks:

1. plenty of battery and good charge.
2. when starter switch is turned on, you can hear the fuel pump whine nicely, but no starter at all.
3. no voltage at the yellow starter switch wire, at the starter, when turning key to start.
4. since my car is a 6 speed, my yellow switch wire, coming off ignition switch, is spliced, for the clutch switch. So coming off the ignition switch, when key turned to start, i see voltage.

Might my problem be the Passkey/VATs system? From the wiring diagram, the yellow wire from the ignition switch goes to the module. I suppose i could make sure I dont' have a break in my starter switch wire, somewhere under the engine bay.

One other question - the wiring diagram suggests (for the (9C1 police) you can simply run the yellow wire from the ignition switch directly to the starter and completely bypass the VATs. Has anyone done this?
 
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#2 ·
Take all necessary safety precautions. (brakes on, in neutral, and others)

Turn key to run. Run a wire from the starter battery cable to the yellow wire stud this will crank the engine.

If the car starts and runs you have a issue with the starter circuit. If it just cranks you have a VATS problem. The light would tell you that it may not be sending the PWM to the PCM.

The Four VATS Modes:

VATS sees a correct resistor value, powers the VATS/starter relay to allow cranking, and sends a PWM signal to the PCM.

VATS sees a open circuit, lights the VATS light, powers the VATS/starter relay to allow cranking, and sends a PWM signal to the PCM.

VATS sees a bad resistor value, does NOT power the VATS/starter relay to allow cranking, and does NOT send a PWM signal to the PCM.

The engine is running and the resistor signal becomes bad. The engine will run and the VATS light will be turned on.


The other quick test is to unplug the key cylinder from the VATS. The VATS should let you run the engine then.


One other question - the wiring diagram suggests (for the (9C1 police) you can simply run the yellow wire from the ignition switch directly to the starter and completely bypass the VATs. Has anyone done this?
The 9C1 still has a VATS. The key resistor value is a wire loop.(dead short) The VATS still sends the PWM to the PCM. Yes the starter relay is missing.

When the VATS is programed out of the PCM this is part of the mod. Some people also just power the relay from the VATS wire harness.
 
#4 ·
3. no voltage at the yellow starter switch wire, at the starter, when turning key to start.
Use a big wire to connect the battery starter wire to the starter solenoid connector on the starter which has the yellow starter wire normally attached. (on most cars a stud and nut) This will crank the engine.:wink2:
 
#5 ·
Thanks man. Just making sure I do it right - you mean i should leave the yellow wire attached at the starter or disconnect it? and basically just 'jumper' the two connections at the starter (heavy wire from the B+ connector to the switch connector)? Or should i run a separate leg from the positive terminal to the switch connector? or does it matter?

One more question - does $eeHack have a VATS select/ECM switch capability? I know it has some controls but limited writing.

Thanks-
 
#6 · (Edited)
One more question - does $eeHack have a VATS select/ECM switch capability? I know it has some controls but limited writing.
I have not tried $EEHack. It sounds great but he explains that he adds code to the PCM and stores extra information as well. Since I am not sure that Tunner Cat will erase or write over the extras I will only try it on a spare PCM.

should leave the yellow wire attached at the starter or disconnect it? and basically just 'jumper' the two connections at the starter (heavy wire from the B+ connector to the switch connector)
Yes leave the yellow wire attached at the starter.Yes just 'jumper' the two connections. Please read the ramblings below for extra information.

When I was checking in the injector information I found a easy way if you have a scan tool. The VATS fault will not turn on the MIL light But it will set DCT 46 (OBDI 46) If you find this you will have to work your way through the VATS circuit.

The other quick test is to unplug the key cylinder from the VATS. The VATS should let you start and run the engine then.

If you can not scan it what I am suggesting is a $0.10 bump switch.

In the good old days when things were simple we needed to rotate the engine to adjust valves, find top dead center, ect.

We would go to Sears or K-Mart (or Snap-On) and get a pre-made switch with wires with electrical clips on the wires. Clip one to the battery and the other to the starter solenoid. Push the button and the engine would crank. If the ignition switch was on run the engine would start.

The $0.10 version is a 4 inch piece of 12 ga wire. Gloves and glasses for safety. Prep the car for starting, then set the ignition to run, Press one copper wire end on the starter's battery stud. Get ready for cranking and press the other copper end to the solenoid's stud on the starter. (sparks will fly do not worry) Hold the wire firm. Remove wire when the engine starts.(or not) Touching the wire to anything else will heat the wire and may start a fire.

You do not have to remove any wires from the starter.

In the bad old days before column locks and computers thieves would clip a wire to the battery and clip the other end to the spark coil. Under the car they would jam a wrench on the two starter studs. The engine starts and the car disappears.

If you do not think this is safe ask some one who works on old cars for a starter/bump switch. They were also part of a kit that would have a dwell/tac meter, and a timing light.

The idea is to totally bypass the starter circuit. The wire is your very crude starter switch.

Touch the wire, engine starts, and you know that the VATS is sending the PWM signal to the PCM which allows the PCM to run the fuel injectors. No VATS signal it may start but it will stall.(no fuel injection after cranking)

If it starts you will still have to sort out what is not passing the start signal. In your case you can start at the column switch, check the clutch switch, and (hardest) check at the VATS/starter relay.

Click on this:

Goldsswagon

Look at starting circuit and pass-key diagrams on Goldsswagon's site.
 
#7 · (Edited)
Just got back in town and jumpered the battery B+ over to the switch, with the key in RUN. Starts right up and runs fine. Looking at the wiring diagram, the yellow wire (circuit 575) coming from the theft deterrent relay might be bad, from connection A2 ? It seems as though the Fuel Enable Output is fine, but the starter enable output is not. The clutch switch is fine and the column switch is also fine (i get 14V when turning key to start, at the yellow wire coming from ignition switch.

I am now thinking the theft deterrent relay, as the fuel enable circuit doesn't go thru this, but only the starter enable circuit.

thanks-
 
#8 ·
If I ever take the dash off I think I will replace that relay.

The good thing is we diagnosed the VATS with a piece of scrap wire. We could have used a code reader voltmeter, or a oscilloscope. These systems are not hard to fix at home if you sort out the logic.

I would have bet on the clutch switch. I always use the clutch switch to power a relay. I do not think they like the high current of the starter circuit.

The clutch switch would have been the second place I would have tried a jumper wire.
 
#11 ·
the wiring diagram suggests (for the (9C1 police) you can simply run the yellow wire from the ignition switch directly to the starter
Now that you know the VATS will let you run the engine you could rewire the starter circuit.

Column to clutch switch to starter may work. Again I am not sure the T56 clutch switch can handle the starter current. If I find some time I will check diagrams at the library.
 
#12 ·
I think it will be fine - the wire gauge in that clutch switch is equivalent to the yellow starter switch wire. In fact, my clutch switch works sporadically, mostly to the 'good', letting you start the car without clutch engaged, like 'the good old days'... (or was it 'the bad old days'?)...;)

If I get some balls, I may try putting in another relay, but its a PITA getting to it, under the dash. I did it once on my roadmaster wagon, but it didn't have the clutch pedal bracket from BBHP. That takes up space.

RT
 
#13 ·
Well, so much for it being the theft deterrent (starter) relay. I put a known good one in (swapped out with my 96 RMW) and it did not start. Then, I decided to jumper, on the relay, connector 30 and connector 87 (these are the two large gauge yellow wires coming in to the relay). Car starts right up. So am thinking it still could be the theft deterrent module not sending the start enable signal to the relay, to make the connection. But could the module be 'bad' on the starter enable circuit side and be 'good' on the fuel enable circuit side?

Any other thoughts?
 
#14 ·
Congratulations on getting to the relay. So many forum member describe the relay as impossible to get to.

You have very little left to do:

Check #85 for +12V with the key in start.

Find a +12V source for your tester. Then check for -12V on the #86 when you turn the key to start.

If you not get -12V at #86 try the yellow-black wire on the VATS check for -12V when you turn the key to start. If the signal is at the VATS you have a wire problem.
If there is no signal at the VATS you could unplug then plug back in the connector.(then recheck) Last check would be to clean the ground connector G104.

G104 is the problem child connector for the PCM, ICM,fuel pump, and many more.
Location: Engine compartment on front of left hand cylinder head. (coil bracket area)
Small black wires on a large ring terminal on a (3/8?) stud.

If none of this helps it is time to bypass the #30 to the #87 with a jumper or replace the VATS.

If you are going to get a junk yard VATS start a new thread. There will be more testing, and new keys with different resistor pellets.(1 in 15 chance it will be the same)

I would like to point out you have spent 4-10 hours on this. Time under the car, time taking off the dash pad ect. Fixing these cars is not easy and the OBD system will not always help.

I too like to have things working and factory. I hate duct tape, unmarked wires, and extra holes in the sheet metal.
 
#15 ·
Congratulations on getting to the relay. So many forum member describe the relay as impossible to get to.
Wasn't so bad - about 45 minutes to remove the damn thing. You don't have to remove dash.

You have very little left to do:

Check #85 for +12V with the key in start.

Find a +12V source for your tester. Then check for -12V on the #86 when you turn the key to start.

If you not get -12V at #86 try the yellow-black wire on the VATS check for -12V when you turn the key to start. If the signal is at the VATS you have a wire problem.
This part I don't understand. Do you mean I need to find a 12V+ source for the + side of my DVM, and connect the negative side of my DVM to #86 on the relay? Why would it show negative voltage when I have the + side connected to a +12V source? I get the yellow purple wire experiment, and the unplug/plug experiment.

If there is no signal at the VATS you could unplug then plug back in the connector.(then recheck) Last check would be to clean the ground connector G104.

G104 is the problem child connector for the PCM, ICM,fuel pump, and many more.
Location: Engine compartment on front of left hand cylinder head. (coil bracket area)
Small black wires on a large ring terminal on a (3/8?) stud.

If none of this helps it is time to bypass the #30 to the #87 with a jumper or replace the VATS.
So I for sure wouldn't replace VATS, but if you simply jumper the two yellow wires going into and out of the relay, presume you'd just cut them at the relay and butt splice together (no room to solder up there). Would you leave the relay plugged in or unplugged - in other words, would having it one way or the other affect anything on the ability to start?

If you are going to get a junk yard VATS start a new thread. There will be more testing, and new keys with different resistor pellets.(1 in 15 chance it will be the same)

I would like to point out you have spent 4-10 hours on this. Time under the car, time taking off the dash pad ect. Fixing these cars is not easy and the OBD system will not always help.

I too like to have things working and factory. I hate duct tape, unmarked wires, and extra holes in the sheet metal.[/QUOTE]
 
#17 ·
New first test for you. Find Fuse #24 (10A Crank Fuse). There should be a diagram on the back of the fuse cover or in the OM. Make sure there is +12 on both sides of the fuse while the key is in start and when the fuse is plugged in. You should be able to probe the two metal tabs on top of the fuse while the key is in start (crank).

If this fuse blew I would not put the original starter relay back in.(new relay time)

I should have suggested this before sending you under the car to the starter but I thought you had checked it.

Find a +12V source for your tester. Then check for -12V on the #86 when you turn the key to start.
The second part of this test I don't understand. Do you mean I need to find a 12V+ source for the + side of my DVM, and connect the negative side of my DVM to #86 on the relay? Why would it show negative voltage when I have the + side connected to a +12V source?
Sorry if this was not clear. I suggest constant a +12V source for your +(red) test lead. Just saying find a easy spot so it is easy to connect. The -(black) goes to the #86. You will not see a +12V voltage on the DVM until you turn the key to run/start. The VATS module switches the #86 to ground.

The electronic parts that switch a ground wire are ten times cheaper than the ones that switch positive power. This is why the fuel injectors, the transmission, and others are connected to positive power and the PCM completes the circuit by grounding the other wire.

if you simply jumper the two yellow wires going into and out of the relay, presume you'd just cut them at the relay and butt splice together (no room to solder up there)?
I would make a male-male quick connect jumper wire and replace the relay with it. Maybe a little tape in case the male quick connect tries to pop out of the relay socket. That way everything is stock.

cut them at the relay and butt splice together (no room to solder up there). Would you leave the relay plugged in or unplugged
If I had to do it that way I would remove the relay.

Tip of the day:
Use a test light. It proves that there is voltage and some current. When you test a circuit with corroded wires or ground connection the DVM may show perfect normal voltage. The test light draws power (amps) through the circuit and may show a problem (dimmer light).
A good example is one of the forum members was having trouble with the gas gauge. When he finally cleaned the ground connection the gauge worked and the power windows moved faster.(more voltage under load) A volt meter can give crazy readings when you have a tail light grounding problem. The test light is easier to use.
 
#18 ·
So here's what I found.

1. Fuse #24 test is just fine. It shows 0V on both sides of fuse when Key is in RUN and then +12V when key is in Start, on both sides.

2. When doing the test on #85, it goes to +12V when key is in START, as it should.

3. But upon doing the test for #86 (and using battery B+ as source), it shows +12V when key is in RUN. Switching the Key to START doesn't change the voltage - it stays at 12V. Does this mean the module (not relay) is bad? (By the way, it does show 0V when key is in Off position).
 
#19 ·
I put a known good one in (swapped out with my 96 RMW) Good Quick check
I decided to jumper, on the relay, connector 30 and connector 87 (these are the two large gauge yellow wires coming in to the relay). Car starts right up.
Assuming you put the jumper wire into the relay socket. We know the high current part of the socket works. (pic1)
1. Fuse #24 test is just fine. It shows 0V on both sides of fuse when Key is in RUN and then +12V when key is in Start, on both sides.
2. When doing the test on #85, it goes to +12V when key is in START, as it should.
Good tests.
3. But upon doing the test for #86 (and using battery B+ as source), it shows +12V when key is in RUN. Switching the Key to START doesn't change the voltage - it stays at 12V. Does this mean the module (not relay) is bad?
No, it means the module should power the relay. I have not checked when the module powers the relay but it makes sense that it occurs when the key is in run and start.
(By the way, it does show 0V when key is in Off position).
This confirms the module is switching the voltage on and off.

So you have run the tests and they are all good. What now?
I put a known good one in (swapped out with my 96 RMW)
Did you try the starter relay in the RMW? If it works in the RMW we can take a relay problem out of the equation.
To be double shure power a relay straight off the battery #85+ and #86-. The click is a good sign. If your meter will do ohms check that #30 and #87 are close/=0 with the relay on.
Pop a good relay back in the relay socket. Turn the key to run. Did you hear a click. If yes the module and the relay are working together.

If it clicks you can back probe the relay socket and again confirm voltage at #87.(pic2) If you can not back probe pierce the wire then tape it after.

If the clutch switch is between the relay #87 and the starter you are back to checking it out.

With the test you have done the relay should be powered by the module. Has the car shown any other signs of gremlins? :eek:
 

Attachments

#20 ·
So I just did the relay click test, for good measure and yes, the relay clicks when you run + to 85 and - to 86. also verified no voltage between 30 and 87 while relay is 'ON'.

To answer your other question, yes, i swapped out the relay from my 95 SS to my RMW, and the relay did work in my RMW (but I should mention that my PassKey light has been on steadily in that car for over two years and no issues whatsoever with starting or running).

The clutch switch is 'before' the relay, between it and the ignition switch.

I had no other gremlins before this incident.

On doing the test for #86 to B+, my Factory Manual states that to
1. disconnect theft deterrent relay.
2. attach a test light between theft deterrent relay connector terminal A1 (which is 86) and B+
3. While observing test light, turn ignition switch to START
4. Does light illuminate?

This would imply that unless the ignition is turned to START, the light wouldn't illuminate (no current/voltage). But in my case, i am seeing voltage across A1 (86) and B+, in RUN. Which i don't believe should be happening, correct?

And when i pop the relay back in, i hear no click.
 
#21 · (Edited)
And when i pop the relay back in, i hear no click.
If you listen you might hear a head banging a wall in Canada.:smile2:

Not sure what is going on but lets try again.

This would imply that unless the ignition is turned to START, the light wouldn't illuminate (no current/voltage). But in my case, i am seeing voltage across A1 (86) and B+, in RUN. Which i don't believe should be happening, correct?
I have the same statement in my FSM. The problem is two fuses are hot at all times, one is hot in run, and the module has no input from the crank(start) circuit. Only the relay gets power from the start circuit. So I can not find a way that the module knows about key start.
I have to conclude the FSM is wrong and it switches the relay -(neg) when the key is in run.
The same FSM tells me about the transfer case(4wheel drive) Hi-Low switch in the text of transmission information. There are other mistakes as well.

On doing the test for #86 to B+, my Factory Manual states that to
1. disconnect theft deterrent relay.
2. attach a test light between theft deterrent relay connector terminal A1 (which is 86) and B+
3. While observing test light, turn ignition switch to START
4. Does light illuminate?
Both the FSM and I suggest a test light not the DVM that can sometimes give false readings.

That said I am running out of tests.

Try the DVM or test light on #85 and #86 You should get a light in run.

The last ideas involve more test wires.
Stick a wire in #85(+) relay socket and connect to same on relay. Ground #86 on the relay. When the key is in start the relay should click.

Stick a wire in #86(module) relay socket and connect to same on relay. Connect #85(+) on the relay to a Always On(B+) . When the key is in run the relay should click.

Unless I am way off one of those two tests will work and one will fail.
 
#22 ·
yes sir, FSM famous for mistakes. My son's 96 caprice it said to thermostat elbow cover to something like 26 ft. lbs.! He broke both bolts and then someone told him correct torque was like 8 ft. lbs!!

But back to your tests:

1. DVM between 85 and 86 - shows 0V in RUN and +9V in START (battery is weak)

2. sticking a wire from #85 on relay socket to same connector on relay, and then grounding #86, gives me a good click upon turning key to START.

3. Sticking s wire from #86 on relay socket to same connector on relay, and then connecting #85 to B+ gives no click in RUN or START.

I'm starting to get a hypothesis...but you're the expert. What think ye?
 
#23 ·
1. DVM between 85 and 86 - shows 0V in RUN and +9V in START (battery is weak)
3. Sticking s wire from #86 on relay socket to same connector on relay, and then connecting #85 to B+ gives no click in RUN or START.
I would repeat the relay in the socket with a charged battery. Just to be sure but I expect no click.

We are down to limited choices.
The opposite results between test 1 and 3 make me recommend jamming a wire into the module's A4 Yellow/Black connecting it to the relay's #86 and then connecting #85 to B+. Key on run and a click means a bad wire to the relay socket. The wire color and pin location should match YOUR 95 FSM. I am using a 94.

If that does not work check and clean G104 and plug the relay in for a check and then repeat the above jumper check as well.

You could jumper B5 Black/White to ground as another check. The wire color and pin location should match YOUR 95 FSM. I am using a 94.Try with relay ect.

I'm starting to get a hypothesis...but you're the expert. What think ye?
Its dead Jim!

If it is not a bad wire or ground connection you have a 1/2 dead VATS.

If it was me I would find a spare one then pop open the old one and look for a bad solder joint or do a little testing to replace a part. I would let 1/2 working VATS lie If I did not have a replacement.

Other people might try to program it out of the PCM and jumper #87 to #30.

Best I can do from here would be to put together a set of resistors to get a JY VATS working for you. You have a 1 in 15 chance of not changing the key pelet.

If you are interested I should have a large list of donors for the pass-keyII system
 
#29 ·
We are down to limited choices.
The opposite results between test 1 and 3 make me recommend jamming a wire into the module's A4 Yellow/Black connecting it to the relay's #86 and then connecting #85 to B+. Key on run and a click means a bad wire to the relay socket. The wire color and pin location should match YOUR 95 FSM. I am using a 94.
Assume you didn't mean to do this test with the module connected up. Doing this first test - putting wire into A4 on the module connector's A4 and connecting it to relay's #86 and then connecting #85 to battery. No click in run or start

If that does not work check and clean G104 and plug the relay in for a check and then repeat the above jumper check as well.
I kinda did this yesterday (cleaned the G104)

You could jumper B5 Black/White to ground as another check. The wire color and pin location should match YOUR 95 FSM. I am using a 94.Try with relay ect.
Could you explain this one a bit more? Does the module actually have to be connected and then i have to find the black wire going to A5 and splice a better ground to it?

Thanks and sorry for my ignorance.
 
#24 · (Edited)
I was actually doing tests 2 and 3 with battery jumped. But i did go back and do test 3 with full battery and it didn't click. Test 2 with a good battery jumped gave the click, so it isn't the battery.

The place i was going was that even though 85 to 86 gives a voltage reading, it may be very weak, which is where your advice on test lights makes sense. Poor ground testing is all about continuity and current and not as much voltage. I did clean G104 and its three or 4 ring connectors with good contact cleaner and reattached. No luck either.

I kinda thought also about the half dead VATS - basically its allowing the fuel enable 'half' to work fine, but the start side isn't.

But the good thing is that i really don't have to program the VATS out of the PCM - remember my fuel circuit works fine, just not the start circuit. so simply jumping the two yellow fat wires (87 and 30) coming into the relay connector is all that is needed.
 
#25 ·
Thanks for working through it. I hope this thread helps some one else. I have had to order $10,000.00 modules for equipment without having the proper tools and software to test with. I like challenges that keep my brain working.

The quirky voltage without current problem is a fail state of a FET device that might be used to drive a relay, injector or light in a car. This is why injector wiring is tested with a Noid light. A regular test light might damage the circuit but a voltage meter might give a false reading.
 
#26 ·
Thank you for being the patient teacher. I will test the two remaining things on the module itself (was actually able to pull the connector off last nite). Things like ground problems though tend to yield other gremlins and also appear intermittent. This happened all of a sudden, so thinking the VATs module issue with an electronic/IC component makes more sense.

I'll revert back this evening.

thanks again.
 
#27 ·
As an aside and unrelated to my 95SS but related to the PassKey system, i did a test yesterday on my 96 RMW. Ran a jumper from 87 to 30 while i had the relay out. Without the key being in START, the starter engaged! My PassKey light has been on in the Roadmaster Wagon for over two years, with no issues whatsoever on startups or anything. Just the annoying light.

When i jump 87 to 30 in my 95SS, at least it waits on the key to move to START.
 
#28 ·
on my 96 RMW. Ran a jumper from 87 to 30 while i had the relay out. Without the key being in START, the starter engaged!
On the 96 they connect the #85 to the start switch. The relay contacts do all the high current switching for the starter. So this is normal for a 96. If I had a high mileage or frequently started 96 replacing the relay would be cheap insurance. Bosch, Hella, or GM would be my only choice as the contacts take a constant beating from arching.

I think you will find the problem on the 96 is your lock cylinder. You can unplug it from the VATS module at the base of the column. You would be looking for a two wire white(?) to purple/white and white/black. Black connector. If you unplug this and the the car starts and the VATS light stays on you have a high probability of a good VATS module. If the key is really beat up try a new key.(every one should have spares!) The real wear item is the contacts in the cylinder for the key pellet. I found a on line (not ebay) lock smith that shipped me 5 keys and a cylinder for less that a local cylinder would cost. You just have to measure the ohm value of the key. The worst part of the job is fishing the new wires down the column.
 
#30 ·
I have been doing under dash work for a long time what I think is normal may not be.

The opposite results between test 1 and 3 make me recommend jamming a wire into the module's A4 Yellow/Black connecting it to the relay's #86 and then connecting #85 to B+. Key on run and a click means a bad wire(Yellow/Black) to the relay socket. The wire color and pin location should match YOUR 95 FSM. I am using a 94.

You could jumper B5 Black/White to ground as another check. The wire color and pin location should match YOUR 95 FSM. I am using a 94.Try with relay ect.
What I had in mind was a variation of "back probing" the connector. See thumbnail.
Instead of putting the probe in the back of the connector you strip a piece of wire and carefully insert it into the connector shell with the brass contact. In this case small solid wire would be a better choice than multi-stranded wire. You can not let one strand touch anything else. If you solder tin the end of the stranded wire.

What I was suggesting in the first case was using a jumper wire back probed into the cavity of the connector that has the Yellow/Black wire at the module shell and connected to the relay.(to see if the Yellow/Black wire is bad)

For the second case I suggested that you back probe the ground cavity of the connector and connect the wire to a known good ground spot. (this would bypass over 10 ft of ground wire)

The back probing work should be done with the key off for safety and you need to double check the wire is pushed into the right cavity and is touching the contact.

If you saw troubleshooting hints #7 for the pass-key it suggests the wires may go bad. These two tests will jumper the factory wires.

The ground is a long shot because the VATS is sending the FMS to the PCM,
Trying to check the wire between the VATS and the relay would be the last fail point before the VATS.

Having gone through this again I just thought of a easier test of the Yellow/Black relay wire with the module unplugged.

With the module unplugged (relay plugged in to it's socket) get a wire in contact with the Yellow/Black wire on the module connector. Connect this jumper wire to ground. When the key is in run: a click confirms the VATS is 1/2 dead. No click and you have a bad Yellow/Black wire. You are shorting #86 to ground like the VATS should.

Keep asking questions. I do not want to lead you to doing damage.
 

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#31 ·
Having gone through this again I just thought of a easier test of the Yellow/Black relay wire with the module unplugged.

With the module unplugged (relay plugged in to it's socket) get a wire in contact with the Yellow/Black wire on the module connector. Connect this jumper wire to ground. When the key is in run: a click confirms the VATS is 1/2 dead. No click and you have a bad Yellow/Black wire. You are shorting #86 to ground like the VATS should.
OK, here's the result. Running a wire from A4 (yellow/black wire on module connector) to ground and relay plugged in. When key is in RUN, nothing. When key turned to START, car tries to start (didn't test a full start/run, battery is weak).
 
#32 ·
If it can start with this test the VATS is the only problem.

Different tools and a little clearer thinking on my part would have shaved a couple of tests off this saga.

Short term fix is a jumper wire. Long term: Programing VATS delete, or a replacement VATS module.

I hope you picked up some diagnostic methods. I hope you will hit the $ store for a test light. I have all sorts of electronic meters but usually go back to a test light for most car work. The throttle body sensor, and gauge sensors makes me dig out my old analog (needle) meter. It will show things only a very expensive digital meter will show.

A very good battle Alchemist.
 
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