help with tail light warning message? 2007 C2 cab

[Schilling]

greetings,

 

perhaps a rookie question here,

 

i recently received a "check right rear tail light" warning upon engine start up, i checked the lights and sure enough three bulbs in the right rear taillight housing were not illuminated when the headlight switch was turned on,,the directional signal light worked, brake light illuminated when brake pressure applied, back up light worked as well.

 

i removed the three suspect bulbs and they all looked good,,i swapped them with the known functioning left hand bulbs and the three previously suspect bulbs worked fine in the left hand housing and the three known good bulbs from the left did not function in the right hand housing.  the fuse checked out fine, no break at all, no visible degradation at all.

 

in the spirit of full disclosure about 4 days before i received the first warning i had removed both tail light housings in order to do some work behind the bumper cover,,but everything went back together fine and a check of all lights showed them functioning as they should,,,,and there were no dash warnings until days later,,,

 

any ideas on what to check next?

 

thanks in advance for any help offered,

 

cheers

KJS

[JFP in PA]

greetings,

 

perhaps a rookie question here,

 

i recently received a "check right rear tail light" warning upon engine start up, i checked the lights and sure enough three bulbs in the right rear taillight housing were not illuminated when the headlight switch was turned on,,the directional signal light worked, brake light illuminated when brake pressure applied, back up light worked as well.

 

i removed the three suspect bulbs and they all looked good,,i swapped them with the known functioning left hand bulbs and the three previously suspect bulbs worked fine in the left hand housing and the three known good bulbs from the left did not function in the right hand housing.  the fuse checked out fine, no break at all, no visible degradation at all.

 

in the spirit of full disclosure about 4 days before i received the first warning i had removed both tail light housings in order to do some work behind the bumper cover,,but everything went back together fine and a check of all lights showed them functioning as they should,,,,and there were no dash warnings until days later,,,

 

any ideas on what to check next?

 

thanks in advance for any help offered,

 

cheers

KJS

 

Yes, go back to everything on that side that you unplugged while working, and check the connections, one may have worked itself loose.

[Schilling]

roger that, i double checked the connections last night when swapping bulbs from side to side, but it certainly wont hurt to do that again. (the one bulb (most inboard/most aft) does work when brakes are applied but does not work when just the tail light should be illuminated)

[Schilling]

i just finished checking all the connections again, and double checked the fuse (and swapped the relevant fuse out with one that was servicing a known good circuit), and checked/confirmed again that one suspect bulb did illuminate when brakes were applied.

 

looked much closer this time at the wires going into the plug ( at the wire harness end) and everything looks solid and well connected; no tears, breaks or anything loose, did the same for the wires on the taillight housing side of the connections,,everything seems to be solid and in good order.

 

any advice on where to go next?

 

again, thanks much for the help and guidance.

 

cheers

[jl-c]

If the feeds are good, check the earth continuity ie. Earth on each bulb holder to a good chassis earth should be zero Ohms or as near as. Only other thing I can think of is the bulb check unit itself or connections to it. Daft as it seems,have you just tried brand new bulbs? I know logic says it can't be the bulbs but logic does not always apply in faults like this ! Corrosion on the contacts will also do this whether it is on the connector pins/sockets or the bulb holders themselves.

Edited August 19, 2015 by jl-c

[JFP in PA]

+1 on checking the grounds.  Weak grounds are a source of unending headaches.

[Schilling]

Thanks for the advice regarding checking grounds, what ended up to be the problem was a "short" in the circuit.  to explain further: (goes back to my earlier statement of perhaps a "rookie question")

 

a couple of years ago i had a willwood systems trailer hitch installed on my car in order to pull a small trailer with track wheels and tires and such.  with that hitch i also had a wire harness installed that tied into the rear lights harness.  

 

the plug on the trailer harness is a typical 4 prong plug, (three female, one male),,the cover for that plug was missing and the male prong was in contact with the hitch receiver, (i noticed that when putting in my bike rack last night into the hitch receiver),,,,when i moved the trailer light harness away from the receiver all the lights worked fine,, 

 

new plug cover is now on the car,,,

 

thanks again for the help!

 

KJS