2007 GMC Yukon wiring / lights problem - FOUND chewed wires near left rear end - update 1st post

[StrkAliteN]

Will try to keep the 1st post simple and focused.

The Rear lighting cluster on the passenger side all 3 main bulbs appear very dim ( driver side rear is normal )

The turn signal blinks at a much more rapid rate than normal most of the time ( starts normal then quickly goes rapid blink ) both left and right position.

The back up / reverse lamps are not working ( appear bulbs are fine - am replacing right now with new ) reverse fuse is fine

I switched all 3 main bulbs from driver side rear to passenger side rear and dim stays on passenger side rear so is NOT the bulbs )

Fuses appear fine.

What is causing this craziness ?

update: June 11

discovered rat / rodent has chewed into wiring harness near the driver side rear end. 2 wires severed some insulation damage to a couple others.
Looks like a few butt splices - some spare wire and waterproof shrink tubing and a heat gun should fix things.

 

[Bill 1960]

Probably a bad ground to the RR lights causing the dim and fast flash.

Reverse switch is what I’d check first on those. Someone will be along that knows where it is, I haven’t been into that circuit on this veh.

 

[StrkAliteN]

This post will blow some minds ( mine is shot wandering what is wrong )

all front lites appear working 100% normal - turn signal bright both sides etc - the large center brake lite appears normal working and brightness. Problem is located rt side rear / passenger side it seems.

1. replaced all rear assembly lamps with brand new and it DID NOT fix the problem
2. For the ease of transmitting info, I will refer to driver side as left and pass side as right. There are 3 main bulbs on both left and right side.
I will refer to these as top - middle - bottom. According to page 502 in my owners manual Top is taillamp/turn signal lamp. Middle is backup lamp and bottom is stoplamp / tail lamp. That does NOT appear to be the functions and replacement bulb pattern ( too difficult to explain ) I am 100% positive I DO NOT have any lamps bulbs in the wrong socket.

scenarios ( there are MANY - here are the main few )

1. Standard lights on: left / driver side appears normal and bright and right side / passenger side all 3 lamps very dim
2. Apply brakes: Rt side / pass side all lites GO OUT ( WTF over ? ) drivers side / left side top lite goes super bright to indicate brake.
3. Apply left turn signal: right side unchanged ( all lamps still very dim ) - left driver side the middle lamp blinks to indicate turn signal. According to my owners manual the middle lamp is referenced as back-up lamp so something is very fucky fucky here. I think the owners manual has the lamp locations mis identified.
4. Right turn signal lamps blink very dim right passenger side. The small side lamp also blinks ( the driver side small side lamp does not blink in turn signal mode )

NOTE: the bottom lamp on BOTH sides never comes on in any function. According to the suspect owners manual ( page 502 ) the bottom lamp is stoplamp/ tail lamp. Once again I think this is wrong.

If someone can confirm top middle and bottom lamps true function would be helpful moving forward.

No damage appears to any wiring and no fuses appear faulty ( obvious power to the lamp sockets )

What in the holy hell is going on here ?? This vehicle sat / not run or started for 4 years 4 months until recent. No prior lite problems and I just noticed this the past few days. Obviously is not safe to drive around with faulty brake / turn signal lites.

has to be something very simple and minor as nothings has been altered or messed with.

I am baffled

 

[StrkAliteN]

Reverse lites do not work and creates all sorts of wizardry I do not wanna try explaining via type.

why does the owners manual incorrectly identify the stack of 3 rear lamps and why does the bottom lamp never ever illuminate ? The bottom cannot be the stoplamp / tail lamp as referred in owners manual

 

[TollKeeper]

If I am remembering correctly, there is a ground strap that goes in behind the drivers side tail light that will cause problems to all 3 light assemblies, including the HMCSL.

 

[Doubeleive]

you just have a short or bad connection somewhere, could be anywhere front or rear, these lights will do some pretty weird shit if there is a short that's the normal part.
you might have to pull the headlight and the tail light housings out and start checking the harness with a meter, the front harness is pretty screwy as it is, you will see a extra ground, look under the truck and see if a critter got under there and chewed on anything. not even sure what the ohm's should be you might have to check the gm upfitter guide diagrams.

 

[StrkAliteN]

pics

 

[StrkAliteN]

pics

 

[StrkAliteN]

The owners manual is WRONG.

The stoplamp / tail lamp 3057 will NEVER fit into the socket that is C position in the owners manual as the lamp plug assembly DO NOT match.

Why the incorrect info in a owners manual ?? I have no ******* clue what is normal now or not normal.

All I know is my right rear lite assembly is possessed by demons and I have no clue how to troubleshoot / fix it

 

[Doubeleive]

owners manual is not going to be helpful in this case at all, you will have to just start checking the harness's

 

[Fless]

owners manual is not going to be helpful in this case at all, you will have to just start checking the harness's

... and clean and inspect the ground for that RR light assy.

 

[kbuskill]

I think the owners manual may be referring to the Chevrolet tail light assembly as the Chevrolet has the reverse light in the center.

It definitely sounds like a ground issue on the passenger tail light. To test this you can back probe the tail light harness and hook the other end to a known good ground and see if your issues go away.

 

[Doubeleive]

you might want to check the harness under the rear bumper, the tail light harness is a sub-harness the connector to the main harness is under the bumper, get under the truck and look up can't miss it.

 

[kbuskill]

you might want to check the harness under the rear bumper, the tail light harness is a sub-harness the connector to the main harness is under the bumper, get under the truck and look up can't miss it.

This^^^

I often take for granted that people just know this automatically.

 

[StrkAliteN]

Thank you to all for info .... I will update as I tear into things

Will post fix also as to help others with similar tail light demons

 

[Joseph Garcia]

The two dual-filament bulbs (turn signals and brakes) are 7443 (ACDelco 15194045 and GMC 13591401)

The single bulb (backup) is 7441 (ACDelco 15524109 and GMC 15524109)

 

[wsteele]

The owners manual is WRONG.

The stoplamp / tail lamp 3057 will NEVER fit into the socket that is C position in the owners manual as the lamp plug assembly DO NOT match.

Why the incorrect info in a owners manual ?? I have no ******* clue what is normal now or not normal.

All I know is my right rear lite assembly is possessed by demons and I have no clue how to troubleshoot / fix it

My owners manual is incorrect as well.

Top is lights on running and brake light. Middle is lights on running and turn signal. Bottom is back up.

You likely have a bad ground and/or a short in one of the right rear circuits.

 

[StrkAliteN]

Got it all buttoned up and everything is working fine.

The check eng lite is what prevented remote start and cruise control from working

The rat also chewed through the fuel vent valve tubing thing that runs up to the gas filler cap and monitors for fumes / overflow.

$55 worth of parts for that and dropping the spare tire to access and then the code will clear and all 100% at that point

Took a few pics of the wire job ( before and after ) ******* rats

 

[Bill 1960]

Thanks for posting the end of the story. Always nice to know.

 

[89Suburban]

Got it all buttoned up and everything is working fine.

The check eng lite is what prevented remote start and cruise control from working

The rat also chewed through the fuel vent valve tubing thing that runs up to the gas filler cap and monitors for fumes / overflow.

$55 worth of parts for that and dropping the spare tire to access and then the code will clear and all 100% at that point

Took a few pics of the wire job ( before and after ) ******* rats

******* rat bastards. Good job.