Short in Backup Light Circuit

[shenandoah75]

I'm trying to find the cause of a short in the TCB2 fuse. I got the helms manuals and have the circuits involved memorized at this point. Several years ago, i cut the wires under the dash feeding the backups lamps and interior lights so i could isolate. The interior lights by themselves work fine, but reconnect the light green wire for backup and it'll blow the fuse within a day.

 

My next steps are to isolate/disconnect the feed from C3 connector in the Relay I/P Block that leads to the rear view mirror and make sure i didn't short the wires in the A pillar when working in there before...

 

If that fails to be the cause, i figure i got two options:

1) short between C3 connector an the lamps

2) short at S211 to RPA or in the line to the RPA control module.

 

 

So my questions:

1) i've seen alot of posts about this same with no concrete resolution. I suspect there's a problem from the factory in the harness. Anyone have a definitive/common cause?

2) anyone know where the S211 splice is located?

 

thx in advance

-brad

[ruggedlife]

if it's not in the A pillar like you said, i'd check the factory distribution block at the rear where the harness feeds into the taillights/trailer wiring. they can get corroded and short out over time. i've seen that often

[gmtech4]

well i looked for a half hr ,s211 is down from BCM ,near center concole ,i couldnt find a pic ,also its C! at relay block not c3...

disconnect RPA instead of finding s211

 

also ,there is a fuse for the back up lamps so im confused why you say its the TBC2 fuse (which doesnt exist ) either TBC2a,b,c, for bcm

 

stop cutting wires god dam it !!!! lol

 

this may be over your head without proper schmatics and experience ,plse take no offence ,,,,shorts are a PITA

 

isolate 1 piece of the schmatic at a time and check ,

 

like i said ,it makes no sence to me ,,,im out

 

good luck

 

WELCOME TO THE SITE !!!!!

[shenandoah75]

thank you both for the tips (and sorry for botching he fuse - was going off memory there but i've replaced it enough, i should know). . but i'm sticking by c3 (pin A) via my 2003 manual 8-220 / 8-1118 (unless the 05's changed)

 

no offense taken at being over my head - my dealer passed on it - and i might just give up too. If i don't find it, i'm prepared to add a relay to the wire coming from BCM and wire from a new source (or tap the trailer backup lamp feed for the relay coil - i tow and plan on adding docking lights to the trailer via that circuit). I would prefer not to go down that route either as i just dropped money on leds wondering if the lower wattage would fix magically fix it. It did not - go figure

 

anyways, on the hunt... thx again

-brad

[gmtech4]

05 changed ,get a better schmatic

[Doug_Scott]

This may be a stupid question/suggestion, but, you did check the backup light socket/bulb didn't you?

[shenandoah75]

not stupid at all well i looked at it when i replaced the bulbs with LEDs a few nights back. I didn't see a problem on inside or out of it...