Dome/Courtesy Lights

[SgtPreston]

The dome lights in my '94 Yukon worked at one time but quit some time ago - I think they are linked by a common ground wire but I can't find where the wire runs to see if there is a break. The under dash courtesy lights work fine. Any help would be appreciated.

 

[Hoesgottaeat2]

In which ways have you determined that they are not working?
By opening the doors?
By using the dimmer switch?

 

[Fless]

Start by verifying that the bulbs are good, using a known good DC supply.

 

[SgtPreston]

In which ways have you determined that they are not working?
By opening the doors?
By using the dimmer switch?

Tried both and also opened tailgate . Have checked bulbs also and have 12V but no ground - aren't all the courtesy lights on common ground?
I'm trying to find the wire for the dome lights without tearing the headliner out.

 

[Hoesgottaeat2]

Tried both and also opened tailgate . Have checked bulbs also and have 12V but no ground - aren't all the courtesy lights on common ground?
I'm trying to find the wire for the dome lights without tearing the headliner out.

I haven't looked personally at this but is there any way you can try running a jumper from the bulb socket to a known good ground? Just to verify it is indeed a bad ground or not?

 

[YukonGTmaster]

I had issues with my dome lights. It ended up being an unserviceable "Override" button at the headlight switch assembly.

 

[east302]

From the 94 manual. The PDF set can be downloaded here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[Eman85]

The switches provide the ground.

 

[SgtPreston]

I haven't looked personally at this but is there any way you can try running a jumper from the bulb socket to a known good ground? Just to verify it is indeed a bad ground or not?

Thanks, I'll try that when I get back to the shop.

 

[SgtPreston]

From the 94 manual. The PDF set can be downloaded here:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

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Thanks, I'm not sure these apply as my 94 Yukon 2 dr. doesn't have an o/h console but I'll go through the other Adobe files you provided - it seems like I need the wiring diagram for the O/H lights and a cutaway view of the wiring location in the roof, possibly from a shop manual?

 

[east302]

Maybe this one?

Edit: this is all from the third PDF from that download link.

 

[SgtPreston]

The switches provide the ground.

Which switches are you referring to that provide the ground - headlight, door jamb, tailgate . . .? I thought the various lights were linked with a common ground wire run to the various switches. When the door was opened, the jamb switch closed the ground and the lights came on - correct?

 

[east302]

Yes, they’re grounded to G202 when a door (jamb switch) is opened.

The white wire on the door jamb connector should be hot at all times, so I’d start there. Jumping the white to black should check the integrity of the ground as well. I’m not sure where the convenience center is on a TBI, but on the 96+ it’s at the interior firewall by the parking brake.

Does the cigarette lighter work? It’s on the same circuit. The circuit’s 25A fuse is good and you have power to it?

 

[SgtPreston]

Maybe this one?

View attachment 389383

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Edit: this is all from the third PDF from that download link.

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That's pretty close so I can check it out tomorrow - thanks.

 

[SgtPreston]

Yes, they’re grounded to G202 when a door (jamb switch) is opened.

The white wire on the door jamb connector should be hot at all times, so I’d start there. Jumping the white to black should check the integrity of the ground as well. I’m not sure where the convenience center is on a TBI, but on the 96+ it’s at the interior firewall by the parking brake.

Does the cigarette lighter work? It’s on the same circuit. The circuit’s 25A fuse is good and you have power to it?

Yes, fuse block is on the interior firewall by the parking brake - I didn't think about the cigarette lighter so that's something else to check tomorrow - thanks for all the help.

 

[Eman85]

Which switches are you referring to that provide the ground - headlight, door jamb, tailgate . . .? I thought the various lights were linked with a common ground wire run to the various switches. When the door was opened, the jamb switch closed the ground and the lights came on - correct?

That's right the switch provides the ground for the dome/courtesy lights. All of the switches that control those lights provide the ground to complete the circuit including the keyless remote module.