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> Reverse light switch smoking when ignition turned on
iwuzazombie
post Mar 24 2023, 06:20 PM
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Hello! My reverse light switch is smoking when ignition is turned on and the #4 fuse blows. Bad switch or what else may cause that? Thanks!

Edit: looks like these wire connectors are bad. Can they be replaced?

Update:
1. everything seemed fine in the car, starting, a few minor electrical weirdness like both blinkers blinking after a second of using them (could be just wrong bulbs i hadn't checked yet) and dash/center console lights not working
2. fuse #4 started blowing and i could smell the electrical smoke
3. went through alot of fuses trying to troubleshoot the problem, checked all the grounds including the tail lights and license plate lights as on forums alot of mentions about those potentially being culprit
4. finally found the reverse switch was smoking, took out the wires which look terrible (as seen in the picture) and then fuse #4 stopped blowing
5. now car turns over but won't start
6. gonna pull the switch today and inspect it and try to replace those male bullet connectors (what a bad design btw!!!)

Could bad connection at that reverse switch cause the car to not start?


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JeffBowlsby
post Mar 24 2023, 07:45 PM
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Is your ignition harness 12-pin connector recently installed and is it aligned correctly on the relay board?

If you melted some wires in the harnesss it will need replacement.
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bkrantz
post Mar 24 2023, 09:05 PM
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Sounds like something is grounded that should not be. Does the fuse blow with the wires disconnected from the switch?
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iwuzazombie
post Mar 24 2023, 09:13 PM
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QUOTE(bkrantz @ Mar 24 2023, 08:05 PM) *

Sounds like something is grounded that should not be. Does the fuse blow with the wires disconnected from the switch?


No the fuse doesn’t blow when the wires are disconnected from the switch.
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iwuzazombie
post Mar 24 2023, 09:35 PM
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QUOTE(JeffBowlsby @ Mar 24 2023, 06:45 PM) *

Is your ignition harness 12-pin connector recently installed and is it aligned correctly on the relay board?

If you melted some wires in the harnesss it will need replacement.


Seems to be seated right.
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Spoke
post Mar 24 2023, 11:28 PM
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QUOTE(iwuzazombie @ Mar 24 2023, 10:13 PM) *

No the fuse doesn’t blow when the wires are disconnected from the switch.


Is this w/o the car being in reverse?

With your ohm meter, with the wires off, measure each side of the switch to chassis ground. Both sides to chassis ground should be open circuit. What do you measure?
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Geezer914
post Mar 25 2023, 01:06 AM
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I bought the Porsche wire connectors from Pelican parts Too bad they didn't make a male plug for that switch.
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Mikey914
post Mar 25 2023, 01:51 AM
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May be as simple as an ignition switch failure?
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iwuzazombie
post Mar 25 2023, 09:00 AM
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QUOTE(Mikey914 @ Mar 25 2023, 12:51 AM) *

May be as simple as an ignition switch failure?


i am not thinking so unless it literally just went out. The car has started just fine without any jiggling of the key or anything. Updating my post with more info.
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davep
post Mar 25 2023, 09:04 AM
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No, I doubt the ignition switch would be in play. The wires in the engine harness connect through the relay board into the main harness. One wire comes from the brake pedal switch and is connected to the fuse via a wire coming to the brake switch. This wire goes to the relay board, through the engine harness, and back to the relay board and from there to the reverse lights. Aside from wiring shorts, there isn't much to go wrong. The switch failure should only make the lights inoperative (if an open failure) or always on (if a short failure). But check to see if you have a short from either pin socket on the switch to ground. That wiring to the socket looks really bad.
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iwuzazombie
post Mar 25 2023, 09:51 AM
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QUOTE(davep @ Mar 25 2023, 08:04 AM) *

No, I doubt the ignition switch would be in play. The wires in the engine harness connect through the relay board into the main harness. One wire comes from the brake pedal switch and is connected to the fuse via a wire coming to the brake switch. This wire goes to the relay board, through the engine harness, and back to the relay board and from there to the reverse lights. Aside from wiring shorts, there isn't much to go wrong. The switch failure should only make the lights inoperative (if an open failure) or always on (if a short failure). But check to see if you have a short from either pin socket on the switch to ground. That wiring to the socket looks really bad.

Thanks. Yeah the wiring is really bad. I just had the clutch and flywheel replaced, you'd think the shop would have seen that. Anyway, i'll check that the ohms on it. Now that has become low priority to the car starting! At least i found the short that was blowing fuse #4!
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IronHillRestorations
post Mar 25 2023, 12:13 PM
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My guess is that the shop incorrectly plugged in the engine harness. I made a similar mistake about 30 years ago, it only took me one fried engine harness and I haven’t done it since.

You need a new engine harness, or ignition harness. Check with Jeff Bowlsby.
bowlsby.net
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iwuzazombie
post Mar 25 2023, 01:53 PM
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QUOTE(IronHillRestorations @ Mar 25 2023, 11:13 AM) *

My guess is that the shop incorrectly plugged in the engine harness. I made a similar mistake about 30 years ago, it only took me one fried engine harness and I haven’t done it since.

You need a new engine harness, or ignition harness. Check with Jeff Bowlsby.
bowlsby.net

Would they have had to remove the engine harness to remove the transmission to replace the clutch?
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IronHillRestorations
post Mar 25 2023, 02:03 PM
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QUOTE(iwuzazombie @ Mar 25 2023, 11:53 AM) *

QUOTE(IronHillRestorations @ Mar 25 2023, 11:13 AM) *

My guess is that the shop incorrectly plugged in the engine harness. I made a similar mistake about 30 years ago, it only took me one fried engine harness and I haven’t done it since.

You need a new engine harness, or ignition harness. Check with Jeff Bowlsby.
bowlsby.net

Would they have had to remove the engine harness to remove the transmission to replace the clutch?


If they pulled the engine and transmission, the 12 pin plug would get unplugged. It’s not hard to get it one row off when going back in.
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jim_hoyland
post Mar 25 2023, 02:14 PM
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QUOTE(IronHillRestorations @ Mar 25 2023, 01:03 PM) *

QUOTE(iwuzazombie @ Mar 25 2023, 11:53 AM) *

QUOTE(IronHillRestorations @ Mar 25 2023, 11:13 AM) *

My guess is that the shop incorrectly plugged in the engine harness. I made a similar mistake about 30 years ago, it only took me one fried engine harness and I haven’t done it since.

You need a new engine harness, or ignition harness. Check with Jeff Bowlsby.
bowlsby.net

Would they have had to remove the engine harness to remove the transmission to replace the clutch?


If they pulled the engine and transmission, the 12 pin plug would get unplugged. It’s not hard to get it one row off when going back in.

(IMG:style_emoticons/default/agree.gif)
Been there too; one row off…. (IMG:style_emoticons/default/sad.gif)
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flipb
post Mar 25 2023, 02:40 PM
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Didn't reconnect the transmission ground strap? Infamous dr914@autoatlanta.com mistake.
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iwuzazombie
post Mar 25 2023, 03:42 PM
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QUOTE(flipb @ Mar 25 2023, 01:40 PM) *

Didn't reconnect the transmission ground strap? Infamous dr914@autoatlanta.com mistake.

It was running fine after I got it back. Fuse #4 was blowing after that which I finally traced to the reverse light switch, which was literally smoking. Up until minutes before I found that which took me a while and blew thru a bunch of fuses the car was starting fine. Once I found that, I pulled those really bad wires out and at that long the car no longer would start. (IMG:style_emoticons/default/sad.gif)
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IronHillRestorations
post Mar 25 2023, 04:25 PM
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QUOTE(flipb @ Mar 25 2023, 12:40 PM) *

Didn't reconnect the transmission ground strap? Infamous dr914@autoatlanta.com mistake.


That’s a possibility too.
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IronHillRestorations
post Mar 25 2023, 05:24 PM
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QUOTE(iwuzazombie @ Mar 25 2023, 01:42 PM) *

QUOTE(flipb @ Mar 25 2023, 01:40 PM) *

Didn't reconnect the transmission ground strap? Infamous dr914@autoatlanta.com mistake.

It was running fine after I got it back. Fuse #4 was blowing after that which I finally traced to the reverse light switch, which was literally smoking. Up until minutes before I found that which took me a while and blew thru a bunch of fuses the car was starting fine. Once I found that, I pulled those really bad wires out and at that long the car no longer would start. (IMG:style_emoticons/default/sad.gif)


I’m going to bet that if you look up a the underside of the trunk floor, you will find the ground strap isn’t bolted to the ground buss. If so take a picture, call the shop and tell them they’ve created a problem. The starter grounds through the transmission via the ground strap. No ground and the starter will use whatever path it finds. Typically it’s the clutch cable.

The reverse switch should never get hot like that.
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iwuzazombie
post Mar 25 2023, 05:50 PM
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QUOTE(flipb @ Mar 25 2023, 01:40 PM) *

Didn't reconnect the transmission ground strap? Infamous dr914@autoatlanta.com mistake.

That was one of the grounds I checked. I actually pulled it off and cleaned it and put it back.
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