I just bought a '99 Tahoe and am having an issue with the headlights.

The daylight running lights work and the high beams work, but not the low beams, on either side.

I've pulled the bulbs and those look good as well as checked all the fuses.

Any thoughts?

 

I'd probe the low beam light sockets and see if you are getting voltage, the headlamp relay may be the cause.
Also if you can pull the steering column shroud and check the connections to the Hi Lo switch, on my 97 the harness had pulled loose and the wires got hot due to the poor connection and melted.
I suspect it was because I used my tilt steering a lot.

 

Thanks for the reply.

So forgive me for asking what may seem like a really stupid question, but wouldn't the light sockets be getting voltage if both the daylight running lights and the high beams are working? The DRL are using the same socket/bulb as the low beams, right?

 

I think so , but I think the DRL's are at a lower voltage. Are your DRL's working?

 

1999 Chevrolet Tahoe - 2WD | Escalade, Pickup (Classic), Suburban, Tahoe, Yukon (VIN C/K) Service Manual |

Headlamps Inoperative - Low Beams
Step Action
Value
(s) Yes No
DEFINITION: This diagnostic procedure should only be used if the high beam headlamps are
operating properly and the low beams are inoperative.
1
Did you perform the Headlights System Check?
--
Go to Step 2
Go to
Headlight
System Check
2
1. Turn the headlamp and panel dimmer
switch to the ON position.
2. Move the headlamp dimmer switch to the
LOW position.
3. Backprobe the headlamp dimmer switch
connector with a J 35616-200 test lamp
from cavity A to ground.
Does the test lamp light?
--
Go to Step 3 Go to Step 5
3
1. Remove the daytime running lamp relay.
2. Connect a J 35616-200 test lamp at
cavity G5 to ground.
Does the test lamp light?
--
Go to Step 4 Go to Step 6
4
1. Re-install the daytime running lamp
relay.
2. Backprobe cavity B at the high/low beam
headlamp with the headlamp dimmer
switch in the LOW position.
Does the test lamp light?
--
Go to Step 7 Go to Step 8
5
Replace the headlamp dimmer switch.
Is the repair complete?
--
Go to
Headlight
System Check --
6
Repair the open in CKT 359 (PPL) between the
headlamp dimmer switch and the daytime
running lamp relay.
Is the repair complete?
-- Go to
Headlight
System Check --
7
Replace the high/low beam headlamps.
Is the repair complete?
--
Go to
Headlight
System Check --
8
1. Inspect for an open in CKT 12 (TAN)
between the daytime running lamp relay
and S120, repair as necessary.
2. Replace the daytime running lamp relay if
no open was found in CKT 12 (TAN)
between the daytime running lamp relay
and S120.
--

 

Yes, both DRLs are workiing.

I guess what I might be asking is - if they're using the same socket/bulb - is it possible that the low beams are burned out but the DRLs aren't?

Not sure "burned out" would be the correct term since the filaments in the bulbs are still good.

I am not very mechanically gifted but I do know how to do some things. And if I know what to square off with, I might be able to fix it myself.

 

from the brief read of the pdf document I would check the light switch...

 

This will give me something to work with.

Thanks for your help.

 

I have a similar problem, but only that the high beams work on a 99 Yukon Denali. Any suggestions?