Rear wiper, Key Fob, TPMS not working suddenly

[Jkust]

Hi all, on my 07 V8 Rainier, all at once the rear wiper & washer, the Key Fob and the TPMS stopped working. I've tried both fobs and new batteries, The TPMS screen on the dash showing the tire pressures is just a black screen. I've checked all of the fuses in both blocks for continuity and can't see a cracked wire when pulling the boot down covering the wires in the tail gate. I disconnected the battery and let it sit. Prior to disconnecting the battery the tpms screen showed the LF, RF, RR, RF tires but no pressures and there was a tpms warning light and message saying it was malfunctioning and after I reconnected the battery, the tpms screen is blank and the warning light and message are gone. Not sure what to try next. Have had the car since since 09 so hasn't had anything crazy happen to it.

Thank you

 

[christo829]

First place to check is going to be the wiring harness where it goes through from the body to the rear hatch. And you'll have to check for continuity, not just a visual inspection, because the wires can be broken inside the insulation. It's a fairly common break point, and since the LGM handles the signals for the key fob and such, it sounds like that's where your issue lies.

Good Luck!

Chris

 

[Mooseman]

Like this:

 

[Jkust]

Thanks, I'll pull the boot back further and see what is going on. I pulled it halfway back and things looked good. Dumb question then, how do I check for continuity with a multi meter when the wire sheeting is still in tact/no broken spot?

 

[Blckshdw]

You can get insulation piercing attachments for your meter probes. I bought this set last week to help troubleshoot what I think is a wiring issue with my riding mower. They've been great so far helping me test for voltage and continuity at multiple points without having to take harnesses apart, or cut into anything. (still haven't found my problem yet )

https://www.amazon.com/dp/B0B9M11CCW/?tag=gmtnation-20

There are other types that do the same thing, just have to pick what works for you

 

[Mooseman]

Most of the time, we just tug on the wires and if the conductors are broken, the insulation will just break.

 

[TJBaker57]

Thanks, I'll pull the boot back further and see what is going on. I pulled it halfway back and things looked good. Dumb question then, how do I check for continuity with a multi meter when the wire sheeting is still in tact/no broken spot?

For a few wires you could test the resistance to ground back at an accessible source.

For example, pull out the fuse(s) for the LGM. Then use your multimeter first to test for 12 volts at the two fuse sockets. Use a thin probe here to avoid damaging the socket. The objective here is to determine which socket is the power source and which socket is the LGM. You may have to turn the key on for this if there are more than one fuse for the LGM. Once you have located the power side turn the key off and then set your meter for resistance and read through the LGM side of the fuse holder to ground. There should be a readable resistance through the LGM to ground. If your meter is autoranging it should read out automatically switching to the proper range. If your meter is manual ranging you may need to try different ranges. If you read an open circuit (infinite resistance) then you have a break in the power or ground circuit somewhere. Could be the power wire or the ground wire from the LGM to frame ground or could even be the LGM itself.

Similarly you can access the serial data wire from the LGM to a splice pack under the rear seats on the right side of the vehicle under the carpet. There is usually a small slit in the carpet for access. Again you would look for a resistance to ground after removing the splice pack comb.

 

[mrrsm]

Re: @Blckshdw 's mention from Post #5...

If you need to use those Cool In-Line Piercing Probes... it will be necessary to apply "Liquid Tape" on any and all of those Punctures to prevent, Rain, Oxygen, Road Salt and Dirt in general from invading those compromised insulation locations and then causing Hidden Copper Wiring Corrosion.

THIS is THE Stuff of Legends... to solve those problems:

https://www.amazon.com/dp/B000FPAN2K/?tag=gmtnation-20

 

[Jkust]

Ok finally got some time to trouble shoot this. I removed that rubber boot from both sides in the hatch in the picture above and yanked on the wires holding one side of the plug and the other side since nothing was obviously broken. The small gauge orange one on the body side of plug broke when I yanked it and it was indeed broken inside the sheathing. I ran a new wire and fixed the issue. I had to rematch the tpms to the tire locations and funny thing one of them must have a dead battery since one won't pair but three will. Anyway, thank you all for your responses. It seems a bit crazy that the smallest gauge wire my wire stripper will even strip is the wire all three of these systems run on.