I am starting a new thread as the original one has become way too big to navigate at this point. I have put a link to this thread in the old one.

Anyway, I believe I have uncovered the source of my backup lights issue.

Today, with key on, gear in reverse, relay #38 installed and tranny connector installed I had no backup lights as usual.

I then took a wire and put one end in the tranny connector at the grey wire pin and the other end in the relay # 38 pin that is 87a and at that point I HAVE backup lights! Whooo hoooo!

Now I just need to figure out what to do to safely and reliably fix this issue with the broken/shorted grey wire from the switch to the relay #38.

All reasonable suggestions would be greatly appreciated!

 

So it was the wire!!!! Unbelievable. What year is your car?

 

Yes, wire is damaged somewhere bewteen relay and switch.

My car is a 1999. Since I don't have any idea of when I actually lost the backup lights this issue could really be years old.

 

Well, at least it's not something else more serious. Good luck with the job, I'd personally try and follow the original wirepath as closely as possible. It'll be time consuming, but shouldn't be too difficult a fix.

 

Start at the Trans Switch connector and make sure the wire is connected to the metal pin in the connector Use the OHMS scale on your meter and male sure you have continuity from the pinto the exposed wire.

Examine the wiring harness that the wire runs in and look for obvious damage to the harness (pinch, scrape, cuts etc) If the wire disappears, go to the fuse box end and do the same as above. Eventually,,,you will find the damaged wire. Then just repair the bad area. It not shorted. When you think of a wiring short, blown fuses, smoke and sparks should come to mind in the same thought.

BC

 

Bill,

I was hoping somehow to run a new wire from relay to switch. I cannot get to the harness as it runs atop the transmission and who knows where, through the torque tube valley etc?

I am not prepared or able to drop all of these items to search for the damage to the exiting grey wire.

Please tell me there is another way!! lol

 

Unless you have had tranny or engine work done, the wiring damage is either going to be right out in the open.. 90% of wiring issues happens at a plug, at the fuse box or some where that the harness is exposed. Just do the basic checks at either end of the run.

If you don't find a broken wire there,,,a wire can easily fished down the tunnel and connected. Just make sure that you run it in some protective plastic armor jacket covering.

 

just run a new wire and splice it with an evnironmental splice at each end

 

Bill,

I will run a test tomorrow same as today onlly I will break the repair on the grey wire break and splice the new wire end to the grey wire out of the connector.

I will also look for some other damage at the connector or fuse box area.

In the event I need to run new wire I will need to know what guage this grey wire is.

BTW - I have mention earlier that I have a rebuilt mn12 tranny in there, with the brace and also back in the Cartek days, when my clutch exloded, the entire engine bay and drive train were removed.

 

I'm glad to see you discovered what the issue is!!...now to fix it. Like Bill said the majority of wiring issues are at the connections! Having said that, and with the work you have had done in that area, it sounds like the problem could be anywhere along it's path....If it was me, I would check both ends of the wire (whatever amount I could get to easily) and if I didn't find the break I'd just run a new wire. You can clip one meter lead to the connector pin and using an ice pick (or similar) with the other lead attached to it, and moving back along the wire poking through the insulation, using the ice pick point, at various points to see if you can locate the open in the wire.

If you replace the wire I would use a 16 or 18 guage wire, that will handle 16 to 22 amps, which should be plenty for that use.

Good luck!

 

I have new wire routed through the tunnel and exiting up front, passenger side near one of the O2 Sensors.

I have the wire encased in a small diameter loom from the exit of the tunnel up through the battery box area and the loom is zip tied a couple of places along the way.

Now for the loom or whatever, from where the wire exits up front to the tranny switch area in the rear, I am not sure what I can use yet.

Question - would a small diameter less flexible loom cause a problem with the operation of the torque tube or will it melt or cause any other issues?

I can reach up a small amount to the top of the tranny where the loom is for the exiting gery wire and zip tie the new wire or the new wire inside of a loom but not sure if that's will be good enough or cause an issue once I drive the car?

Thanks in advance for your help and ideas.

 

this is probably what's wrong with our car. the lights come on when we unlock the car with the fob, but nothing when we put it in reverse

 

I would think my situation is rather extreme and not the norm.

If you have b/u lights on approach (with the fob locking/unlocking) but not when you put into reverse it is most likely a fuse or the backup switch in the tranny.

The b/u switch costs about $20 and installs on the passenger side of the transmission.

There is a way to check to see if the switch is bad or not. The info for that is buried in my original thread, probably in more than one place.

You'll need the car up in the air and a digital multi-meter to check ohms on the switch with the negative battery terminal disconnected.

If you wish to try that and have questions you can post or pm Bill Curlee or you can pm me and I can try to help you out. I amno expert but know a lot more now than I did before.

 

I havn't been following your thread,butI have an electrical problem that might be related to yours,couple days ago got a check eng. light came up code 443 which is evap purge solenoid,fact. manual requires scammer which I don't have so I checked where I could which included a voltage check at the solenoidas this solenoid is hot (12 volt) in start and run and is controlled by PCM BY GROUNDING in checking the schematics the supply voltage is circuit #339which supplys voltage to a number of circuits including the clutch switches (2),MAF,evap. vent solenoid reverse lockout and B/U lights protected by 10 amp fuse under hood #19 all other circuits checked out.Evap. purge sol is on top of engine drivers side checked wire from evap. sol. to where harness goes behind engine and likewise checked harness from fuse to back of engine.I'm not sure what method is used by GMto tap into this community power source (circuit#339) I don't think there are weatherpack connectors but my suspicions are this is where the break is in my case and yours I ran a seperate wire and that circuit came back on line so for now I have a seperate feed f/evap.pur.sol. There is one area you might want to check,remove batt and batt. tray the harness runs over some sharp metal edges in that area I at first thought that was my problem but its not.I hope this helps ,Tracing elec. gremlins can be frustrating and time consuming.One more thing the wire gauge for these circuits is the thinnest I have seen in an automotive application I would guess 20 or 22 gauge which may be a contributing factor to these breaks

 

Good info! Thanks and let's hope this is the last gremlin we have to trace!

 

what ended up being the fix?

 

Hard to say. This thread is only 4 years old.