no high beams

[chimp koose]

I just got a 97 gmc 1500 for my daughter to drive and she informs me the headlights are a mess . I checked it out and there are daytime running lights , low beam lights , but no high beams . I doubt both bulbs would go at once so what do I start checking ?It looks like the dimmer switch may be the culprit but I hope not because it appears to be a bear to access.

[chimp koose]

Also I did not see a high beam indicator light in the dash when they were switched on although I was checking in full daylight

[wayne petty]

perhaps this will help..

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/23/1a/29/large/0996b43f80231a29.gif

these could be DRAWN wrong...   the wire colors are correct.. you can probe to the left of the steering column in the ignition switch connector harnesses.. yellow wire in either top or bottom row will be power from the ignition switch..

in the later diagrams..  the dimmer switch is on the NEGATIVE side of the headlights.  

so the power is sent to the COMMON terminal on the head lights..

the low beams can be connected to ground thru the dimmer switch to ground..  or thru the daytime running light module.. which will give them current thru a resistor to reduce power for the DRLs.

the upper and lower harnesses are missing from this image..

http://i.imgur.com/zDbdXyJ.jpg  i have them somewhere.. i just have to get them all together for a picture..

i am hoping that you have a set of tiny TORX E sockets.. i don't know if it takes an E4 , E5 or E6 to get the screws out of the column shroud.. or which size it takes to remove the external torx turn signal and wiper switch mounting screws...

i don't know if you can get these up there.. they are the only thing i found to fit..   i have driven small nuts on the splines to get the fasteners off but that is not possible on the column shroud usually..

http://www.harborfreight.com/6-pc-14-in-drive-e-socket-set-68017.html

oh.. the dimmer switch is crazy expensive also..  depending if you have cruise control or not ...

you can always identify the 3 wires on the bulk head connector and splice in a conventional dimmer switch as a temporary fix..  as long as you do so between the column and the bulkhead connector shown above..  just to get them working.

[wayne petty]

to save you hours of hair pulling....


http://i.imgur.com/twXkCRT.jpg  to make it easy to print..



when you turn on the headlight switch.. you should have power on E13..  

when you have the LOW BEAMS selected you should have power on E12 a pink wire..

when you have the HIGH BEAMs selected  you should have power on E11..

this should save you several hours of tear down and head scratching..

that connector will be on the inside of the firewall above the brake pedal to the left of the steering column and rotated 90 degrees.. i don't know which way it will be rotated.  in looking at the factory 98 astro van wiring diagrams i happen to have.. the green wire to the HIGH beam is direct..

hope this saves you some time..  you could just have a burned contact or yes.. burned bulbs..

[chimp koose]

Thanks Wayne now all I have to do is find the time to fix it . Just finishing a 2 month summer holiday . Isnt it funny how this stuff happens right AFTER you have the time to look at it  

[wayne petty]

at least with that last image i put up.. dimmer switch diagnose time has been reduced to 2 minutes with a test light ..

[chimp koose]

Thanks again.