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Ok, so after pulling nearly the entire harness out, here is what I found. Everything disconnected from the engine harness. PCM out. Battery out. Pulled header on pass side off to access harness and inspect it - all ok. Someone has been in this harness because there is black duct tape covering soldered-together splices. All that crap came out and will be done correctly.

The devices on fuse #4 all share a ground. That ground is also shared with the windshield washer motor (among other things..). The wiring at the plug was bad, and grounded against the aftermarket catch can elbow at the valve cover, which bridged the hot and ground at the plug - blowing #4 fuse. Why #4 and not the one for the motor? Who knows. Electricity is magic. Bought a new harness connector. FYI - if you want it "now", like I did, AutoZone had it for $49. RockAuto has it for $8. I bent over and bought it today.

Before I re-wrapped the harness and plugged it back in, I checked resistance to the body from the #4 fuse in the underhood fuse block. #4, #5, and #6 all had 12 ohms resistance to ground - which isn't good. Pulled fuse block and removed terminals. #4-#6 all share a link in the panel, coming off a pink lead, and its a thick one. Traced that down and it went into the pass firewall. Pulled pass side dash apart, and found the connector where that lead joins up into another plug with yellow, red and pink wires going out. Disconnected it. Checked ohms to ground at the pink underhood box - infinity. Checked resistance to ground at the pink-wire connector going into the dash - 12 ohms. So at least I know the issue is inside the car now.

Wiring diagrams show the pink, yellow and red connector as going to the ignition switch. Pink also splits off and goes to fuse #12. Pulled the #12 fuse in the inside panel, which isolated the pink to just the ignition switch. 12 ohms resistance, so now I am pretty sure it is the switch. Turned key while meter was connected and the ohms jumped to 13 when the key was turned, then back to 12 at the 'off' position.

Cliffs notes question: is the pink lead at the ignition switch supposed to have ground-continuity? I suspect not, as that wouldn't make much sense. However, seeing as how this car has a mix of metric and SAE bolts on the same f-ing part (the ones holding the glovebox to the dash....) I thought it would be worth an ask.

If not, it is interesting that the car ran with the ignition switch f-ed up. Its also interesting that it didn't go up in a puff of smoke and fire.

Anyway, any of you LT1 gurus care to offer any perspective?

Thank you
 

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The ignition switch on these cars seem to last. I would not worry about it unless there are problems. Does your car have stereos car alarms and other accessories patched in?

My quick answer is that I own several multi meters but rarely use them for vehicle work. I use a test light.

all had 12 ohms resistance to ground - which isn't good.
Is the pink lead at the ignition switch supposed to have ground-continuity?
All your 12ohm measurements are telling you is that there is a 1Amp load on the circuit. This does not seem like a big deal. The ohm measurement may not be accurate. If you want a real measurement measure ampage across the fuse holder with the fuse out.

Checked resistance to ground at the pink-wire connector going into the dash - 12 ohms. So at least I know the issue is inside the car now.
I do not think this is a "issue". The pink from the ignition feeds 7 different fuses inside the car. Your 12ohms could be the chime box , the air bag, turn signals, or the VATS.
 

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Anyway, any of you LT1 gurus care to offer any perspective? Thank you
...Given you discovered some ? solder/wiring within the harness that some PO did I suspect when moving/unplugging/plugging the harness for the engine R&R that caused the suspect connections to now...not connect or ground.

You may have discovered more under the dash as who knows what any PO did like aftermarket stereo or alarm system or even if the car was jacked sometime before.

yeah the "need it now" $ for a plug sucks but that's what the brick & mortar stores have over online....like the exploding wallet temp gauge connector on PS cost at AZ vs RA

Your diligence is notable...ideally you get this buttoned up with the harness re-work
 

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Discussion Starter #4
The ignition switch on these cars seem to last. I would not worry about it unless there are problems. Does your car have stereos car alarms and other accessories patched in?
Thanks for your reply. It does have a stereo head-unit, no amps, and a small alarm with keyless entry. No starter kill or remote start. That being said, I took the measurements with everything disconnected in the engine harness, and the engine harness disconnected from the ignition harness.

My quick answer is that I own several multi meters but rarely use them for vehicle work. I use a test light.
My meter is a Fluke 88v - pretty much the gold-standard for automotive electrical work. My trust in the meter is high.

All your 12ohm measurements are telling you is that there is a 1Amp load on the circuit. This does not seem like a big deal. The ohm measurement may not be accurate. If you want a real measurement measure ampage across the fuse holder with the fuse out.
I really appreciate you trying to tell me what's going on here. That being said, while I can easily do just about anything mechanically - I have the electrical knowledge of a housefly. So you're saying that even though holding one lead to the ground and the other lead to the pink wire shows 12 to 40 ohms resistance to ground, its normal? I think I get it. The meter sends out a small charge into the wire to test resistance, and that resistance isn't necessarily its ability to see a ground, but is instead the resistance of any switches or electrical components in the line. Is this correct?

...Given you discovered some ? solder/wiring within the harness that some PO did I suspect when moving/unplugging/plugging the harness for the engine R&R that caused the suspect connections to now...not connect or ground. You may have discovered more under the dash as who knows what any PO did like aftermarket stereo or alarm system or even if the car was jacked sometime before.
The duct tape in the harness was a big surprise. At least they soldered it. LOL. There is actually a lot of non oem wiring under the dash that I discovered when I installed the head-unit and alarm. I tore a lot of it back out and re-did it, but its entirely plausible that I missed something.
 

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The meter sends out a small charge into the wire to test resistance, and that resistance isn't necessarily its ability to see a ground, but is instead the resistance of any switches or electrical components in the line. Is this correct?
A resistance measurement should only be used when you are sure that you are only measuring a wire from one end to the other with no connections to the car.

What I think you measured when you found 12ohms inside the car was the second pink wire that is factory spliced to the ignition switch. The 94 FSM shows that this wire feeds: the chime box , the air bag, turn signals, instrument panel indicators, or the VATS. I was confused by your reference to fuse #12. I know a 96 is different but I am assuming the 94 is the same as a 95. Have you checked the "power distribution" diagram to confirm that the pink wire from the ignition switch powers circuits in the two fuse boxes?

A ohm measurement that includes a electronic device (chime ect) will result in a reading that will not match the actual power consumption of that device.

My meter is a Fluke 88v - pretty much the gold-standard for automotive electrical work. My trust in the meter is high.
Wish I had one. That said a $10 meter will give less precise results but they are good enough to get the job done for 99% of ohms , volt, and amp work in a car. Again if you can not be 100% sure that you have disconnected all electric loads from a wire you can not trust a ohm reading.

For example:
I checked power on the pink lead at the MAF and it's very low. I checked resistance on that lead to ground and it shows 1.2k, so its definitely bleeding off voltage to ground somewhere.
When you measured 1.2Kohms at the MAF you probably did not unplug:air injection pump relay, egr valve, evap purge valve or the L/R O2 sensor. The meter is measuring these parts and giving a reading. This does not help you find a problem.

When you measured the voltage at the MAF sensor you need to compare the voltage to the battery. So ground the meter to the battery then test battery voltage. Then ground to battery and measure MAF voltage. On a old car I would expect some difference between the two but would hope to see 0.5V or less.

left 02 wasn't swinging like it should Changed out left 02.
From your O2 issues it may still be in this area. As I am not a mechanic I get Bank# vs Left/Right mixed up. Are you sure you are on the correct side?
What I was suggesting is that you unplug your right O2 then scan to see that the data stops. You may have software that defines bank 1 and 2 reverse from what GM defines them.

If fuse #4 blows try unplugging: air injection pump relay, egr valve, evap purge valve and the L/R O2 sensors.Then plug in one at a time and see if one blows the fuse.

Shorts to ground are hard to find. You may have to look at all the wiring and maybe buy a "short tracing" tool.
 

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There are quite a few crimped/spliced connections in the
engine harness that are wrapped with duct tape from the FACTORY! ;)
Believe it or not...

Nab
 

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Discussion Starter #7
There are quite a few crimped/spliced connections in the
engine harness that are wrapped with duct tape from the FACTORY! ;)
Believe it or not...
Nab
Dude. For real? Can't tell if serious...
 

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Yes, black duct tape especially where grounds are crimp/spliced.
No solder however.

Nab
 

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Yeah factory duct taped grounds/splices are pretty much standard on a zillion different vehicles.
They hold up fine, usually for decades and decades.
Nothing wrong with redoing them if you desire though.
 
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