Fog Lights

[knightrider2000]

Guess this is what i get for buying a used truck that was run on gravel roads alot.. but here goes..

I have enclosed a link to a shcematic for the fog lights(kinda big to post here) that i got from my dealer..  i have checked both bulbs, fuse, relay and the BCM, from what i can tell there are no loose connections.. the only thing that i havent checked is the ground distrubution cells.. simply because i cant find them..  any help would be Great!

Heres The Link

http://users.bscn.com/~mgilliam/f-lamps.jpg

Matt

G.

99 z71 4X4 ext. cab 5.3L

[Guest Friz]

Two major things need to be tested here, power and ground. Get a multimeter. Test lights are nearly useless in trouble shooting. Radio Shack has cheapos for about ?. They work fine.

From the light itself there are two wires, purple and black.

Check black for continuity against a good chassis ground. It MUST be clean and make good metal contact. Resistance should be no more than two or three ohms.

If it does not read good continuity, follow that wire by hand, looking for breaks or corrosion at terminal lugs.

If it is good, check the purple for power at the light for 12vdc or better.

If power is no good, check the other end of the power at the fuse box. Step by step, move your power checks closer together from each end. Along the way, visually and by feel, check every inch of the wire and terminals. Electrical problems can be maddening. They are often difficult to nail down because wires are often routed so that they won't be seen.

If you come to a place where it would be very difficult to get to the wire, go past it to a more accessible spot and check. If your meter reading is the same, your problem is probably not in that area.

Most wire damage would be in an exposed place. Corrosion on terminal lugs(ground lugs) can be anywhere.

I hope this helps.

[knightrider2000]

I dont think it is ever getting power to the fuse box to go out to the lights...  i have done some multi-testing, but with little luck..   do you think i might see if my dealer will reprogram the BCM for me again?

[Stepside Z]

I would ask for the reprogram. If the fog lights were not original equipment they may have never been programed into the computer.

[knightrider2000]

The tech said they were not programed into it, but they look orginal, i cant find any kind of connections other than factory..  i am wondering if the BCM could "forget" that it had fog lights

[illmac77]

my truck originally didnt come with fog lights,ordered the original set and installed them myself last step was to take the truck to the dealer and have them programed into the computer , wasnt happy at that point called them up and the dealer said it was like ? to program them into the comp. well i ended up not paying for it since the tech. said not to worry about it. that was very cool, but anyway your truck  might have lost the program some how, your dealer should be able to fix that problem for you. hope this helps

[Pastmaster]

i am wondering if the BCM could "forget" that it had fog lights

My buddy has a 99 too, and it turned out his BCM was bad for it.  We replaced it with another BCM and reprogrammed it and they worked.  

I'd have the BCM programmed.

 

[knightrider2000]

Pastmaster,

How much was a new BCM?  

Matt G.