Hi,
I'm hoping someone might be able to point me in the right direction locating the main grounding points on my 1992. Last week I took an hour drive and when I went to start the car again it would not turn over. A few min later it did start but I then had no gears (automatic). I got it towed home took the console apart and the shifter cable was broke and a little of the shielding was melted. I thought it must have snapped and either was laying on the exhaust or touched something electrical and that's why it slightly melted. I got a new cable and installed it and thought I was good to go. I drove the car about 90 min total time (in 10-15 min intervals) since replacing the cable and it happened again except this time it completely melted the cable. My friend thinks it's a ground problem and the car is using the shifter cable in place of a ground which is causing it to heat up and melt. Any thought or have you ever heard of something like this? I've put about 4000 miles on the car since I bought it. The water pump, cap rotor, wires and plugs were the last mechanical thing done about 300 miles ago. I have two amps and a capacitor that were wired to the battery and no fuses for anything blew. I think it has to be a big power source causing it possibly the capacitor or starter? I'm lost with it at the moment. I installed another shifter cable but I'm afraid it's going to happen again since I've not found why yet. Although I was not sold on it being an electrical problem at first something had to have caused this shifter cable to melt like this.

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Hopefully someone more knowledgeable will jump in, but there are a couple of main grounds on the engine on my '96, so I'm assuming it would be similar on the '92. One is on the driver's side of the block, up above the oil filter. The other is on the driver's side on the bellhousing. There are also some chassis grounds up front - one is tucked up under the brake master cylinder, not far from the battery. And some others for the lights up near the radiator.

Thanks.. I found the one that has the strap going just under the master cylinder (next to the battery). I'm not sure if that goes to the belhousing or block but both ends looked good but I cleaned them anyway. I can not locate the other main one though

That theory makes no sense to me unless you did something wacky with your stereo install, but it's easy enough to test it with a DMM rather than chasing wiring.

The cable sits right next to the exhaust so that seems like the obvious source of melting...

Hi. The stereo has been in for a year and this just started last week. I only think possibly the amps or capacitor because they ran directly to the battery and it seems like it would have to be a big power supply.. I'm totally with you on the heat from the exhaust (this is what I originally thought when the original cable melted and broke last week) but if you look at the pictures this new cable & the original broke and melted at the shifter in the car. The section that bolts to the trans has no damage. And both times this happened I turned the key and the car did not turn over. Then smoke out of console

Also all three cables (just installed another) have 2" of clearance to the exhaust. Believe me I want it to be that simple but when I factor in the car not turning over both times, the cable smoking in the console (the car had been off for an hour) and two heavy cables melting at the same spot I'm kind of thinking he is right?

You mentioned the digital multimeter. Any idea where or how I would test it?

Had the same thing happen to me but at the other end.

I was sitting at the bank drive through with the motor running. Bank can be slow at times and it took a while. Got done finally and went to put it in gear and the shifter felt like mush. Wouldn't hardly do anything. I got it home though and the cable looked similar to yours but it was melted on the end with the grommet on it. Turns out I had a slight exhaust leak before the 02 on that side and the PCM was throwing gas to it at idle and getting that side of the exhaust really hot. I found a used OE cable on ebay (30.00 TMD)and wrapped it with heat shield tape. So far so good. Of course I fixed the exhaust leak too. So check your fuel trim on that side and make sure they aren't on the high side on that side. I used that sticky back heat tape to wrap the cable with. Good luck!

Another thing, try to find a OE cable if you can. The aftermarket ones are junk.

I would be shocked if the shifter cable is acting as ground.

Also, I would be equally shocked if it DID ground, that it would generate the amount of heat needed to a) melt that plastic and b) shatter that wire. Consider this - it would take 500F + to melt that plastic so thoroughly. This means that the ground was so damned hot, you should be arc welding with the alternator...

I am betting on an exhaust problem. I can't believe the cable is touching the exhaust, the way it is routed would make that nearly impossible, but, as Weave suggests, a leak, jetting hot gas as the cable, DOES make sense.

Just a few thoughts...

If you think it's the capacitors or whatever just disconnect all of that and see how it does. Also, those cables can be a PITA to change. You don't have a big ass open hole where the cable goes through the body do you? Heat can go right in there and collect in the console. I know, way out there but ya never know. How's your tranny temps? If it has problems it can throw out some heat. Did the first cable look like it was original? Like I mentioned earlier the aftermarket cables are crap including the insulation on them.

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I had not paid attention to it being the interior side that's melted. That does suggest electrical.

If it's electrical, you have a large unfused/large-fused hot wire contacting that cable.

Which strongly suggests amp wiring. Does the amp power wiring run through the console?

You didn't hear any arcing?



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Disconnect cable at trans / turn everything electrical on / test for voltage & current from the loose end to trans.

But with that I was mainly thinking about chasing a disconnected ground. Not as useful for chasing an intermittent hot...



Hey, will that rubber boot at the trans end of the cable come off, and if so can I have the one off the burnt cable? Mine is torn...

Thank you for all the input here... I'm going to wrap the cable with some heat shield just in case. All the temps and charging voltage seem to be normal. Both new cables I installed are about 1 1/2" - 2" away from the exhaust so it's not laying on it but I don't know if any leak is in the area blowing on it. I think if that was the case I would see some sign of melting in that area though?

Also both times this happened I got in the car which had been off for about 15 min the first time and an hour the second time and when I turned the key the motor did not turn over. Everything lit up but the starter never turned over. The VAT system is bypassed with a resistor. When it happened the second time the first time I started the car that day I did get a strange noise from the starter almost like a loud buzzing but it did turn over and start right up. I actually shut it back off right away and tried to start it again and it did the same thing. The starter not turning over is what confuses me and adds the element of mystery

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I had not paid attention to it being the interior side that's melted. That does suggest electrical.

If it's electrical, you have a large unfused/large-fused hot wire contacting that cable.

Which strongly suggests amp wiring. Does the amp power wiring run through the console?

You didn't hear any arcing?Quote:

It'll come off. Just cut the metal tab. I used a zip tie to fasten it back with.

hmm you asked "You didn't hear any arcing?"

Possibly the buzzing I heard when I turned the key?

Starter motor possibly?

92

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Very interesting.

OK you got me curious enough I went out and crawled under my car to look...

So the burned portion you have appears to be both inside and outside the car.

The only wires anywhere near the cable on the underside are the trans wiring.

The only part of the cable that is near the exhaust is the very end at the trans.


Still seems to point to something in the console.



Noise you heard could have been starter solenoid chattering because it couldn't get enough current because dead short was pulling all the current.



Fishing expedition:

Are there any burn marks on the cable or ends? (on the metal)

Did the cable strands come out of the end on the first one like the one you have pictured?

How does the cable grommet look? Tight to the cable?

No burn marks on either cable. The first (original) cable was a clean break where the cable meets the metal portion at the bracket for it in the console. The rubber coating was melted but just as if someone held a lighter to it. The grommet looks good and no marks or melting. Nothing in the console is melted. We did find the cig lighter fuse blown but I am thinking one of the strans of the cable hit it as it came undone since it is right next to it. That trans wire you mentioned looks fine as do all the other wires and looms I've looked at. Since you phrased it that way it did sound like a chattering sound.

Thank you to everyone for helping with this.

vis_croceus you are welcome to it. Just let me know where to send it

Well the third shifter cable is connected. Left the console open hooked up the battery turned the key and as soon as the starter kicked over sparks out of the shifter cable. Amp & capacitor are unhooked

Wow.

Oh, idea!!!

The hot wire to the starter, from the battery, goes up and over the bell housing. I am wondering if that has been bit.

I would disconnect the starter end, then with someones help, giggle the starter wire and have someone watch at the bell housing for sparks.

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Disconnect upper end of cable. Pull injector fuse to keep the car from running.

Test voltage between upper end of cable and ground (1) with key off (2) with key in run (3) while cranking.

If nada, check voltage where it connects to the shifter under same 3 conditions.

What Andy said. There are several wires/wiring harnesses that are secured to the bellhousing bolts. I would check those to see what if anything is chafed or rubbing on it.

Matthew

Quick update.. Removed the negative battery cable and it looked perfect. New cable is going in tomorrow anyway because I already bought it. Then going to move on to the positive battery cable (bought that also). Got a new starter also just in case.

Saturdays Update: finished replacing both the negative & positive battery cables today. Both original cables appeared to be fine but we replaced them anyway. The new cables are slightly bigger than the originals. Also replaced the starter motor. I have not had the original starter tested yet but I'm going to take it and see if we can have an amp draw test done on it. I spoke to a GM tech and he said if it's drawing more than 250-300 amps that might be the issue. Reassemled everything and test drove it for 15 min and everything seems ok so far. I did leave all the stereo equipment unhooked for now and am now testing that to make sure everything is ok with it. I did a continuity test from the positive power line (unhooked) to the frame and I'm getting a signal which I shouldn't be. I tested from the connector at the battery to the first block where the line split and when I disconnected from the block to the amps I lose continuity. So that issue (if it is one) is between the spliter and amps. It's possibly pulling a ground from something connected to it

Also cleaned and replaced the ground strap from the bell housing. It was covered in udercoating and fiberglass resin from some work done prior to me getting it. We also added another 2" wide ground strap to the block

Sounds like you've almost got it nailed!

you will get continuety... As long as the ground is attached to the battery, you will have a complete circuit.

I am also curious about your usage of "amps".

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I get the feeling you are using amps as something other than the measure they are.

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Or are you referring to the stereo amps?

Sorry I was referring to the stereo amps...

And tonight it started all over but the shifter cable did not burn up yet. Drove it today for about 20 min. Shut it off for 5 started it up and drove another 10 and all was fine. Tonight I drove it for 45 min shut it off. When I tried to start it I got the chatter, it turned over & started. Tried again and when you turn the key nothing.

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Not surprising since all you did was replace good parts...

Get in there and do some diagnosis!

Found it... It was the purple ignition wire to the starter exposed and touching a piece of metal. Thanks to everyone for the help. As suggested the test with the meter at the shifter found it