fog light problem

[Evil Iron]

Just inherited a 90 454ss. One fog light out; figured bulb burnt out. Bulb was good. In mean time other light stopped working. That bulb is good also. Looking at wiring diagram my next thing to check was fuse. But noticed there is no fuse in the box for fog lamps. No inline fuse that I can find. According to wiring diagram there is suppose to be a orange wire from fog light relay to a fuse. Grounds seem to be good. Maybe replay? How can I check that before spending money on something I dont need. Any thoughts as too what I should look for next? I hate wiring problems. Thanks

 

[GoToGuy]

So , since you inherited a truck , if you have the owners manual, read the operation descriptions about fog lights it will reference fuses. How do know the bulbs are good? If you can't see a broken filament you have test it, ohm meter or separate 12 volt source( broken at base appears good, nope). Broken light switch.
Don't guess, seems is a guess, check it, test it, unseen corrosion is like cancer, silent unseen.
Voltage in bulb receptacle, ensure you good test light w/ good ground.
Basics done, no luck, next step get out the service manual.
Their a free download here in forum, get your year. Book 1 chapter 8 electrical. Book 2 chapter chapter 5 diagrams, trouble shooting. My best advice.

 

[Evil Iron]

Didnt get a owners manual; will have to order one. How do I get to those downloads?

 

[df2x4]

Didnt get a owners manual; will have to order one. How do I get to those downloads?

Here's a link to the service manual thread, it's stickied in the "Engine Performance + Maintenance" section. If you don't see your year in the original post keep scrolling, other members have added to the collection over time.

https://www.gmt400.com/threads/88-98-service-manuals.43575/

 

[packer0440]

I think the power for those goes through the “DRL” (daytime running lights) fuse, I’d check that. Beyond that, look at the wiring manual mentioned above to guide you. Hopefully your switch is good, cause they are hard to find and very expensive if you do find one.

 

[Evil Iron]

Thanks for showing where those downloads are. will put the wiring diagrams to use tomorrow.

 

[89obsSB]

I think the power for those goes through the “DRL” (daytime running lights) fuse, I’d check that. Beyond that, look at the wiring manual mentioned above to guide you. Hopefully your switch is good, cause they are hard to find and very expensive if you do find one.

I don’t recall their being drl’s in the 88-94. I know for sure there is in my 97. My 89 was not equipped.

 

[packer0440]

I don’t recall their being drl’s in the 88-94. I know for sure there is in my 97. My 89 was not equipped.

Sorry if that note was confusing; based on what I’ve seen in the diagrams, that fuse will be hot if the truck is so equipped, whether it be fog lights, DRLs or both, the power for them runs through that fuse. Also, all trucks shipped to Canada in 1990-up came with DRLs.