C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Power seats short

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Old 04-07-2017, 09:23 PM
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drk1313
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Default Power seats short

When I got my '92 back in November the power seats and door locks did not work. The circuit breaker was pulled (never a good sign), and when I installed it, it became hot and had to be pulled right away. After reviewing the FSM, I checked the ground for the system (G202) and found it was hot with full battery power. There are 2 grounds together at that location under the pass kick panel. I removed the seat ground - reinstalled the circuit breaker - and the door locks now work, and no overheating. I pulled the grounds off of the power seat switches and there was still 12v at the ground wire. I then disconnected all of the connectors under the seats, and still have power at the ground. Is there another location that this wire is prone to short? My next thought was to pull the seats and keep tracing it back to the G202 location.
Old 04-08-2017, 07:31 AM
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Solderhead
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Can you post a picture of the diagram?
Old 04-08-2017, 10:53 AM
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drk1313
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Originally Posted by Solderhead
Can you post a picture of the diagram?

Old 05-02-2017, 11:21 PM
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Default Short found

After a lot of multimeter work I finally found my short. As I said earlier - there was fully battery power at the ground wire for the seats (by the pass door jamb). I also had continuity from the power AND ground wires on the seat switches to the ground wire. I set the meter up and noticed the voltage started to vary as I moved the orange and black wire that is buried on the driver's side of the console. I took it all apart and fished out the connections and there was a bare metal jumper from the power to the ground. Based on the FSM, this looks like where they note a 3 amp diode. The diode was gone and the bare wires were touching and causing all of the problems. Check the connector in the picture and you'll see the bare metal coming from each side. What a pain the the butt! I cleaned all of the switches (lumbar and bolster) and lubed everything and it all works properly now. Anyone know the original purpose of the diode? I assume an overload would trigger a short and blow the breaker?


Last edited by drk1313; 05-02-2017 at 11:24 PM.
Old 05-03-2017, 09:32 AM
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9T3VETTE
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Good thread. Where was the diode and connector located at?

I've got a similar problem that I believe was caused by what dog suggested, jumping in reverse polarity. My door locks and seats work, but lumbar and bolster does not on both sides (fuse good, etc) and last year I found the fusible link to the alternator to be holding on for dear life.

I have not done a ton of DMM work but it seems everything is OK to the point where the main connector goes under carpet. Maybe this diode or another in a different location is my issue.

Glad you got your figured out!
Old 05-03-2017, 10:51 AM
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Originally Posted by 9T3VETTE
Good thread. Where was the diode and connector located at?

I've got a similar problem that I believe was caused by what dog suggested, jumping in reverse polarity. My door locks and seats work, but lumbar and bolster does not on both sides (fuse good, etc) and last year I found the fusible link to the alternator to be holding on for dear life.

I have not done a ton of DMM work but it seems everything is OK to the point where the main connector goes under carpet. Maybe this diode or another in a different location is my issue.

Glad you got your figured out!
The connector with the diode is under the console on the driver's side - about where your hip/thigh would be. I ended up taking apart the driver's seat in order to make enough room to pull the side of the console back to access the connectors. They are in a very difficult location. Oddly enough, the other seat switch connector does not have the diode and I don't see any sign there was one there. C4s come up with some challenging gremlins for sure.
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Old 09-10-2021, 10:35 AM
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Default c4 power seats power locks

Originally Posted by drk1313
When I got my '92 back in November the power seats and door locks did not work. The circuit breaker was pulled (never a good sign), and when I installed it, it became hot and had to be pulled right away. After reviewing the FSM, I checked the ground for the system (G202) and found it was hot with full battery power. There are 2 grounds together at that location under the pass kick panel. I removed the seat ground - reinstalled the circuit breaker - and the door locks now work, and no overheating. I pulled the grounds off of the power seat switches and there was still 12v at the ground wire. I then disconnected all of the connectors under the seats, and still have power at the ground. Is there another location that this wire is prone to short? My next thought was to pull the seats and keep tracing it back to the G202 location.

hello i have the same issue the power seats and power locks do not work my mechanic says it is most likley a short to ground are you able to help me he is quoting 1k and if i can fix it myself i will totally do it myself i can pay you i just need help to diagnosis if you can walk me through this
Old 07-13-2022, 02:31 PM
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Any luck on getting it fixed?
Old 07-29-2022, 11:11 PM
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Herbally
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Originally Posted by drk1313
After a lot of multimeter work I finally found my short. As I said earlier - there was fully battery power at the ground wire for the seats (by the pass door jamb). I also had continuity from the power AND ground wires on the seat switches to the ground wire. I set the meter up and noticed the voltage started to vary as I moved the orange and black wire that is buried on the driver's side of the console. I took it all apart and fished out the connections and there was a bare metal jumper from the power to the ground. Based on the FSM, this looks like where they note a 3 amp diode. The diode was gone and the bare wires were touching and causing all of the problems. Check the connector in the picture and you'll see the bare metal coming from each side. What a pain the the butt! I cleaned all of the switches (lumbar and bolster) and lubed everything and it all works properly now. Anyone know the original purpose of the diode? I assume an overload would trigger a short and blow the breaker?

Looks identical on my 1992. Anyone have ideas on choosing a replacement diode? Looks like it's wired in reverse bias. What PIV voltage rating? 40V?
Old 08-16-2022, 09:04 PM
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JLCK93
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Hello - First time on the forum. I just found this same issue with my 93. I believe you have answered this, but wanted to clarify your fix. Did you just clean the the connectors and it worked? Did you cut the diode wires from the connector? Just wanted to be clear on how you fixed. I have been trying to find a harness with this connector, but if you fixed with no diode, I will go the same route. Thanks . . .
Old 08-17-2022, 11:10 AM
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Herbally
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Originally Posted by JLCK93
Hello - First time on the forum. I just found this same issue with my 93. I believe you have answered this, but wanted to clarify your fix. Did you just clean the the connectors and it worked? Did you cut the diode wires from the connector? Just wanted to be clear on how you fixed. I have been trying to find a harness with this connector, but if you fixed with no diode, I will go the same route. Thanks . . .
Just removing the short will make it function but without replacing the diode, you leave yourself open to reverse voltage from a component that shares a ground. I just bought 3A 20V Schottky diodes so I can replace it. Don't know if it's the right kind of diode but makes me feel better than doing nothing.
Old 08-17-2022, 08:44 PM
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Originally Posted by Herbally
Just removing the short will make it function but without replacing the diode, you leave yourself open to reverse voltage from a component that shares a ground. I just bought 3A 20V Schottky diodes so I can replace it. Don't know if it's the right kind of diode but makes me feel better than doing nothing.
Thank you for the suggestion. I will look into this and most likely follow the route you described. Thanks again
Old 09-10-2022, 11:04 PM
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is the connector pictured above under the seat? if not where is it located
Old 09-11-2022, 09:13 PM
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Herbally
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Originally Posted by rberge12
is the connector pictured above under the seat? if not where is it located
It's in the center console on the driver side.
Old 09-13-2022, 01:35 PM
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Thanks, I found the connectors that you are referring, all are fine. I disconnected under seat connectors and all on driver side console, Breaker still gets hot. I believe the short is in connector 219 or before. Problem is I can not find the connector under the pass side hush pnl. The FSM states "IP left of passenger glove box" benn under there and cant locate it.

Anything else I should look at?

Any help would save my sanity!
Old 09-13-2022, 04:42 PM
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Herbally
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Originally Posted by rberge12
Thanks, I found the connectors that you are referring, all are fine. I disconnected under seat connectors and all on driver side console, Breaker still gets hot. I believe the short is in connector 219 or before. Problem is I can not find the connector under the pass side hush pnl. The FSM states "IP left of passenger glove box" benn under there and cant locate it.

Anything else I should look at?

Any help would save my sanity!
Is that diode still intact? Seems common for that to burn up/short out which causes this issue. Double check that out isn't shorted with a meter. Otherwise, I am not familiar with the other connector.
Old 09-13-2022, 09:05 PM
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A 20v Diode replacement should work. Find the same amperage. Make sure its wired in correctly. The side with the stripe is the cathode and according to the diagram that is connected to the Or/Blk wire.
If it's connected backwards you'll know by the tell tale smoke.
Old 09-14-2022, 03:49 PM
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Thanks y'all! I found the diode ( connector d-side console) was the short, It was still in tact but shorted internally. I cut the diode out of the connecter and all is working. I ordered diodes from amazon 20v 3 amp x 10 for 7 bucks......

Again, you guys are awesome!!!!!!!
Old 02-10-2024, 02:45 PM
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Fatt Vette
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This is an older thread but...

Same situation here with my 92 ZR1, no power seats or door locks. The factory service manual was not very helpful but it did lead me down the failed diode path.

Sure enough, clipped the diode out and no more short to ground! The factory diode is physically huge, I hope the replacement I have will be rated high enough.

P6KE15A



This is what I found it under the tape:


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