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Greg A.
Greg A., Master Troubleshooter
Category: GM
Satisfied Customers: 8106
Experience:  Working with Electronics & Cars for 25+ Years
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99 suburban tail lights dont work. All others work fine.

Customer Question

99 suburban tail lights don't work. All others work fine. Bulbs look OK
Submitted: 7 years ago.
Category: GM
Expert:  Greg A. replied 7 years ago.

Hello & Welcome,

 

Does this mean that the brake lights and the backup lights work, or are they out too?

 

Thanks

Customer: replied 7 years ago.
Turn signals work, hazard lights work, stop lights work, head lights work. Tail lights don't work with the headlights. I looked at the bulbs and they appeared fine. I switched the taillight bulb with the turn signal bulb and it work in the turn signal spot. I did this for both sides.
Expert:  Greg A. replied 7 years ago.

I am so sorry - my wife had a kitchen emergency that I had to take care of.

 

Let me check the schematics and see what I can find.

 

Do you have a test light or multimeter you can use to do some testing?

 

Thanks

Expert:  Greg A. replied 7 years ago.
One other question: Do the license plate lights work?
Customer: replied 7 years ago.
I don't. The instrument panel light does not work. The light on the A/C recirculation button does not work. The license plate light does not work.
Expert:  Greg A. replied 7 years ago.
How about the front parking light? Do they work?
Customer: replied 7 years ago.
I assume you mean when I turn the headlight switch to the first position to get parking lights....They don't work. The headlights work and the high beams work.
Expert:  Greg A. replied 7 years ago.

OK - Now we are getting somewhere. Most of those lights are driven by the same circuit. Here is the schematic.

 

graphic

 

I have highlighted the fuse and the switch that controls most of the lights.

 

What I would do is check the fuse with a test light or multimeter to see if power is coming into and going out of that fuse. If that is OK, it would be time to check the pins on the headlight switch to see if it is working.

 

If you don't have the test tools, you can just check the fuse visually (look at it) and see if it looks like it is blown.

 

Please let me know what you find.

 

Take Care, Greg A.

Customer: replied 7 years ago.
It's definitely not the fuse. The fuse also controls the interior lamp and it shut off when the fuse was removed. So you're saying it's the switch?
Expert:  Greg A. replied 7 years ago.

That would be the next suspect. But I could not say without testing. I would recommend that you get a cheap test light or meter (they are only $5-$10) and make sure power is making it into the switch (at pin H of the schematic) and then comes out when the switch is turned on (pin S of the schematic).

 

Please let me know what you find.

 

Take Care, Greg A.

Customer: replied 7 years ago.
Will do. Tomorrow
Expert:  Greg A. replied 7 years ago.

Sounds like a plan.

 

Please let me know what you find.

 

Take Care, Greg A.

Customer: replied 7 years ago.

I really think it's the switch. I looked it up online and found that the switch assy is available at the local parts store. I will buy it and see if the new one works. If it doesn't, I'll simply take it back. I'm almost positive this will work.

 

I'll click accept as soon as I find this works.

Expert:  Greg A. replied 7 years ago.

Hi again,

 

As a quick test, you can carefully put a jumper wire from pin H to S and see if that makes the lights come on.

 

Thanks, XXXXX

Greg A. and 5 other GM Specialists are ready to help you
Customer: replied 7 years ago.
Lights still don't work, even with the switch changed out.
Expert:  Greg A. replied 7 years ago.

Hi again,

 

Did you place the jumper wire between the two pins I mentioned above, as a test, before replacing the switch? Did you get a test light or multimeter to do some testing?

Customer: replied 7 years ago.
No I didn't. I'm at work now and will get a test light on the way home in a few hours.
Expert:  Greg A. replied 7 years ago.

Ok - Thanks.

 

You might want to consider an inexpensive multimeter too.

Customer: replied 7 years ago.
It turned out to be the fuse. #9 as you said before. I really don't get it, because I checked them. I was jumpering across the connector like you said and got no lights, which means it's not the fuse. Then I tried jumpering across other parts on the connector, like an idiot and heard a small pop. I rechecked the fuse and found it blown. I replace the fuse and all now works. Go figure.
Expert:  Greg A. replied 7 years ago.

Hi again,

 

A good test light or multimeter comes in pretty handy most times to figure these things out.

 

I am glad you got it worked out and that I could help.

 

Take Care, Greg A.