98 Suburban Headlamp knob Question

[c_becker11]

Ok, good, if me , with no head or runnings in headlights on position , I would check the headlight switch first. Has it had some kind of internal disaster. You know it's got power coming in , is it sending power out in headlights on position. Yes or no.

Thanks GoToGuy!
I will check that tomorrow as I'm now at work for the evening. I'm not the best with electrical stuff - is there a part in the manual that shows how to test those switches? I'm assuming I have to pop my whole dash cover off?

 

[someotherguy]

The pictured position of the switch is your "park lamps" position where you would only have exterior lights -other- than headlights on. You may be noticing headlights in that position as a function of the DRL system but they shouldn't come on until you are in gear with park brake released.

You have three positions of the switch. OFF, park lamps, and headlights.

It's common on the DRL-equipped trucks for people to experience headlight switch failure but still have headlight function thanks to DRL's. DRL operation would be indicated by the green headlight icon on your dash being lit.

Richard

 

[GoToGuy]

The complete 98 OE service manual is here use search bar at top " service manuals" there will be a post with link to the downloads. The 98 is four books/ volumes. Get all. They started changing the chapters layout so the headlight electrical is in section 8 , volume 1. Operation , diagnosis, wire diagrams are there. Good luck.

 

[c_becker11]

It’s either going to be the headlight switch that you pictured or the multi function switch. I had a similar problem not having high beams and it was my multi function switch.

95burban, I think you nailed it. I was bewildered - I changed the headlight switch and the 50 amp fuse and nothing - still not working. Then I hopped in it to drive and after shifting into gear the lights came on. Consequently when I shifted it back into park they shut off again so that makes me feel like it's coming from the steering column and most likely that multi function switch that you mentioned. Was that hard to replace?

Thanks again!

 

[someotherguy]

Then I hopped in it to drive and after shifting into gear the lights came on. Consequently when I shifted it back into park they shut off again

Your DRL's are working as expected.

Edit: let me qualify that claim with the fact I haven't driven a DRL-equipped gmt400 in probably 13-14 years. Gmt800 DRL behavior may have influenced my opinion on how they operate, because that's what my '06 does. DRL's on in gear, off in park. It may be that gmt400's are on when the truck is running.

Beyond that, if you suspect the wiring in the column (the headlight wiring from the multifunction switch is very tiny) you can try operating the tilt function up/down and see if that affects the headlights. I've seen a few that were damaged from frequent tilt use.

Richard

 

[c_becker11]

Your DRL's are working as expected.

Edit: let me qualify that claim with the fact I haven't driven a DRL-equipped gmt400 in probably 13-14 years. Gmt800 DRL behavior may have influenced my opinion on how they operate, because that's what my '06 does. DRL's on in gear, off in park. It may be that gmt400's are on when the truck is running.

Beyond that, if you suspect the wiring in the column (the headlight wiring from the multifunction switch is very tiny) you can try operating the tilt function up/down and see if that affects the headlights. I've seen a few that were damaged from frequent tilt use.

Richard

Yep! You nailed it too. I tilt the steering wheel everytime I get in the vehicle. When tilting it up and down the lights will flash on and off so I'm 100% positive now that it is the multi function switch. The part is only 70-100 bucks and I was quoted as much as 800 dollars from a local dealership to replace it!!! Looks like I will be tackling it myself - thank you all for your help!

 

[someotherguy]

Yep! You nailed it too. I tilt the steering wheel everytime I get in the vehicle. When tilting it up and down the lights will flash on and off so I'm 100% positive now that it is the multi function switch. The part is only 70-100 bucks and I was quoted as much as 800 dollars from a local dealership to replace it!!! Looks like I will be tackling it myself - thank you all for your help!

You can probably repair the wiring if you're handy at all with a soldering iron and heat shrink tubing. The most likely area for damage is where the wiring bundle bends at the tilt knuckle. Won't require removal of anything but the column shroud plastics. Once they're out of the way you can turn the headlights on and give the wires the wiggle test and localize the break. I can't recall if that section of the wiring is included with the multifunction switch or that's part of the dash harness that connects to it.

Richard

 

[dmhscorpion]

Your DRL's are working as expected.

Edit: let me qualify that claim with the fact I haven't driven a DRL-equipped gmt400 in probably 13-14 years. Gmt800 DRL behavior may have influenced my opinion on how they operate, because that's what my '06 does. DRL's on in gear, off in park. It may be that gmt400's are on when the truck is running.

Beyond that, if you suspect the wiring in the column (the headlight wiring from the multifunction switch is very tiny) you can try operating the tilt function up/down and see if that affects the headlights. I've seen a few that were damaged from frequent tilt use.

Richard

MY GMT400 Tahoe with DRL, the DRL comes on with the ignition key in the on position, unless you click the parking brake down one click, which turns the DRL OFF.