03 Suburban w/ strange electrical issues

[grtpalfd]

Hello forum members, I am new to this forum. Did alot of research but not able to find info on my problem. But I did enjoy finding lots of great info.

I have mutiple issues, but maybe they are all actually related.
2003 1500 Suburban. 5.3L. 133,000 miles
1: Speedomoter-usually sits at 120+. My research on this forum tells me that the cluster may need repaired. The guy in Minnesota on ebay sounds like a good repair

2: Activate the LEFT turn signal and the 4-way flashers will activate. This happens about 75% of the time I use the left turn signal. Sometimes the 4-way will flash a few times, then just the left turn signal. Other times the 4-ways will flash continuously without ever going to Left turn signal. This never happens with the Right turn signal, only the left.

3: This is the issue that prompted me to the forums today. During the winter I discovered that mice had chewed some wires on my utility trailer. Well it was 80 degrees today near Pittsburgh and it was a good day to fix the trailer wiring. I found the bad wiring in the trailer tongue. Those mice chewed through the wire harness cover, the electrical tape and all 4 wires!! I replaced the bad wiring and all lights worked EXCEPT (there is always an except!) the right brake light on the trailer. All lights works fine on Suburban. Tested bulb, it is good with OHM meter. Moved bulb to Left trailer light...it works there. Left bulb does not work in right trailer light. I have the wife in my truck working the brake. I have 12 volts at the contact of the light, but still no brake light. I clean the contacts and confirm bulb is contacting the metal strip. Still no light. I then test the light fixture again and I still have 12V but I notice that the brake lights are out on the truck. Wife says she is no longer holding the brake. I now discover that I am seeing 12V of current at the Right trailer brake contact even when the brakes are NOT on. I then go directly to the trailer hitch and confirm the same thing. I am seeing voltage on the Right trailer brake contact without the brake pedal being applied. The strange thing is that even with this voltage, the bulb will not light. I pulled the Right trailer Stop/Turn fuse and this voltage went away. Replaced the fuse and voltage appeared again. Now I am thinking the problem is with the Suburban and not my wiring repair. I moved the trailer to the wife's Dodge Dakota and all trailer lights work fine.

So as you can imagine I am perplexed and I am in fear of high dollar repairs! Could this trailer brake issue and possibly the turn signal/flasher issue be caused by the electronic control module or some other module/computer on this Suburban? Or do you think I just have some really hard to find wiring issue on the Suburban?

Thanks for the oppurtunity to ask this long drawn out question.

George

[unplugged]

Sounds like it could be a short in the turn signal switch. The stoplights are wired on the same circuit as the turn signals. Pricey item at around $150. But you might want to check out the turn signal/flasher module shown in the attached diagram. A short in that module could also be the cause. You can find complete diagrams by following the links in dwill3015's post here: GMTC
Suburban Parts

[r_w]

I'm in agreement that it is probably a short. Either in the switch or in the turn signal module. Based upon the symptoms, it is more likely in the turn signal module, and induced by the shorted wires on your trailer.

I'd recommend checking the trailer wiring one more time (you probably already have!) and replacing the turn module. It is a dealer only item, but cheaper than the switch.

[Dr_Zero]

I would vote for the turn signal switch also.

If you go to buy one check out ebay you can get one for 40-60 + shipping vs the 150+ elsewhere and check it close there is the model with and without cruise control dont get the wrong one, and good luck!