No Electricity at Instrument Panel Fuse Panel / Pass Key Issue?? - Chevy Impala SS Forum
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post #1 of 7 (permalink) Old 02-24-2016, 08:02 PM Thread Starter
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No Electricity at Instrument Panel Fuse Panel / Pass Key Issue??

For the last year the Pass Key light had been on in my car, but it still started and ran just fine so I didn't worry much about it. I read the Pass Key sticky in the forums and decided I'd bypass the key resistor when I got a chance. Well, after a trip to the vet the car wouldn't start, I tried to jump it with no luck, and just as I was about to call for a tow I tried again and it started. After I had bought all of the required resistors and a soldering iron to do the job, the anti-theft kicked in again late at night, this time waiting the 3-4 minutes didn't work. But, my wife showed up with the spare key, which got it started since the resistor isn't worn down on that key.
This brings me to the current problem, I try to go to work on Monday and the car won't start, I knew it was the anti-theft, but I tried to jump it anyway to no avail. So, now I'm thinking the resistor pickups in the ignition switch are just own out because I'm using the spare key that got the car going before. I do the resistor bypass, my key resistor is 523 ohm and the bypass resistor was 508-509, within the tolerance of the GM manual. But still no start, no lights, nothing. I changed my bypass resistor to get it to 518 - 519 to get it closer to the key resistor but nothing.
Now I start checking for power:
- battery - good, body fuses - good & power present
- body harness connector C207 behind RH kick panel - good & power present on all three pins.

Now when I go to the instrument panel fuse panel, all fuses that should be hot at all times are dead. I checked continuity between the dead fuses and connector C207 and they all ring out. I checked continuity between:
- Pass Key fuse #34 and the connector on the Theft Deterrent Module - Good
- Relay on the panel with the TDM and the TDM connector and C207 - Good
- Ignition key resistor connector and pins B7 & B8 of TDM - Good

I am at a loss, the last thing that I want to check but I think it will require the removal of the dash (which I don't want to do if someone on here has another idea) is to locate S276 and check that splice to see if power is present there. That is where power from connector C207 goes to before being distributed out to the fuse panel and the ignition switch. The manual says this splice is located in the "Body Harn, approx 13 cm from SDM breakout", I know where the SDM is supposed to be, but can't see it--again leading me to think I'm going to have to drop my dash.

Have any of you seen anything close to what I've described? I've banged my head on this for three days now and am getting no where fast, pleeeeease help.
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post #2 of 7 (permalink) Old 02-25-2016, 12:09 PM
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Multiple issues?

From your references to the manual we are talking about a 94-95?

I will base my suggestions on the 94.

Quote:
all fuses that should be hot at all times are dead
S276 goes back to MAXI fuse 11 under the hood. You did not state that you checked it.

Quote:
locate S276 and check that splice to see if power is present there
Before you do this check the MAXI fuse 11 is passing power. (test light on both fuse pins should light).

If the MAXI fuse 11 is OK check the other legs of the splice 276. Do you have power on the two ignition switched fuse banks? In acc and run 6,7,11,15,14,(12 RM) and 24 . The other bank is run only 16,18,17, and 20.

If you do not have power on 35,33,34,27,28,26,29, and 30 but the other two banks have power in run you may have a splice fault.

Quote:
I checked continuity between the dead fuses and connector C207 and they all ring out.
Bad contacts can ring out but fail under a real load. I am a electronics guy but I do most tests like this with a test light as a multimeter will show voltage on wires that will fail to light a test light.

If you do not have power to all three banks AND you are sure the MAXI fuse 11 is good you may have a wire problem between MAXI fuse 11 and the splice. Use C207 to split the problem.

You are unclear about when it does not start. Is it cranking the starter and not starting or is it not cranking?

There is a lot on mixed information on the VATS system.

A new key (your spare) should measure the same across the key pellet as at the the plug to the lock cylinder at the column. Where wht/blk and ppl/wht plugs into the (orange?) wires that go to the lock cylinder unplug and test the wires to the lock cylinder with the good key(ohm reading should be close to the key value). A worn out cylinder should be changed out before it causes other issues. You should get the same reading at B7 and B8 when you unplug it from the module.

Quote the internet: the only person VATS stops from starting the car is the owner.

I have read that if you unplug the lock cylinder from the VATS the VATS considers it a malfunction and lights the PASS KEY FAULT. The internet says you can still start the car. The internet claims thieves cut the key sensor wires and break the ignition to steal the car.

The only real VATS test is to check the VATS outputs.

PWM (A3 DK BLU) some meters will see this as a AC signal but it is a pulsating DC (40-60 Hz). This allows the injectors to run.

A "ground" (battery to) on A4 yel/blk grounds the Theft Deterrent relay and lets the start power from the ignition to get to the starter.
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post #3 of 7 (permalink) Old 02-25-2016, 01:37 PM Thread Starter
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Thanks for the advice, my Impala is a '96, forgot to mention that. I will get a load light today and start running through all of the points I've checked with the multi-meter again, as well as the ignition switch fuse banks. Maxi-fuse 11 and C207 both showed 12 VDC but I'll use a light to double check.

To clarify, my car is completely dead, will not crank and no lights illuminate. Even when I turn the ignition over nothing happens. I'll remove the lower dash to gain better access to the aft side of the fuse panel and hopefully a clear view at S276.
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post #4 of 7 (permalink) Old 02-25-2016, 05:28 PM
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1/2 system

Checking for the turn signals in run would be the first check the radio (if factory wired) would be the second. If they do not work the fault may be between C207 and the splice.

Be careful 60 A fuse will let your probe melt or start a wire fire if you make a mistake. If you have smaller Maxi fuses plug one in for the probe tests.

If you really have power at c207 You may be able to use the half way system. In your case try to find the red wire 1/2 way to the splice and use a small sewing Needle (pins are usually to flimsy to use) and a pair of pliers to drive the needle into the wire. If you have power here move forward to the splice and check it just past that point. Keep moving the probe point forward until you find a dead spot then probe a 1/2 way point back to the last good spot. If you tape over the hole you know where your check points were.

If you find a burnt out wire think about checking your starter solenoid. My personal opinion is that a bad starter solenoid can burn out the ignition switch, theft relay or wires without burning out the 60 A Maxi fuse. The more I look at the starting circuit the more I think I will put a manual resetting breaker between the start switch and the theft relay.

From the GoldsWagon diagrams I can not see anything else that is on Maxi fuse 11 that does not have it's own fuse.
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post #5 of 7 (permalink) Old 02-26-2016, 08:11 PM
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The larger orange wire term at the ignition switch can burn up and cause a dead issue(no lights,no crank,etc...).It's on top of the lower column.Check for signs of heat/melt/burn't leads.
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post #6 of 7 (permalink) Old 02-27-2016, 12:32 PM Thread Starter
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So I feel a bit smarter and confident about working electrical issues on my car but I also feel like a complete moron, I dropped the dash and removed the upper air duct to gain access to splice S276. It had continuity with C207 all the way to the 60A body fuse, so next I reinstall the fuse and reconnect the battery, I had roughly 10 VDC on my Fluke at the splice and at C207, but nothing at my fuse panel. I go back around to the engine bay and wiggle the positive battery wire and lo and behold the damn car comes alive. Upon closer inspection of my positive cable, a good third of the wires going into the termination aren't doing anything. So I go back to the splice and fuse panel, both now show 10-11 VDC, the load light worked at all fuse points, and I have continuity and power at the TDM, TDM relay, & Ignition Switch. Got a new set of cables from Innovative Wiring on order, once those are installed, I will be able to check if my Pass Key bypass resistor is good.
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post #7 of 7 (permalink) Old 02-27-2016, 02:01 PM
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So close

Sounds like a half hour and a steel brush would get you on the road.

Some on the forum have reported the stud nut on the body fuse box has been loose. Worth checking as well as cleaning the battery terminals, starter terminals, and others before the new wires come.

New cables on a 20 year old car seems like regular maintenance in my part of the country. People in the no snow areas seem to have fewer issues with the starter/battery cables. Less salt less problems.

Mine has seen little or no winter. I usually upgrade the battery/starter cables on my vehicles but I have not done the B4U because I want to be sure that my routing of the cables does not expose them to extreme heat like the factory heat shielded ones. I usually use welding cable and it is not rated for engine heat. I am also keeping a eye out for the 105 deg C cable that should be used. Using cable two gauge sizes heaver that stock is what I usually do.

When I think corrosion is a problem my "test light " is a headlight with a voltmeter to check voltage drop (10%-20%Max). You can actually measure the voltage drop on a starter cable to decide if it should be changed. Many of the 16 ga/18 ga wires in a "rust belt" car that look good fail the current test of the headlight. It only takes a small break in the insulation to allow salt and water in. It then travels the whole length of the wire corroding it. Voltage without current may be why some guys keep replacing fuel pumps. I would like to do the headlight check on one of the fuel pump eating cars.

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