1994 GMC C1500 Headlights Flash Off Then On When Using Dimm

Tiny
BILL52
  • MEMBER
  • 1994 GMC C1500
  • V8
  • 4WD
  • AUTOMATIC
  • 18,000 MILES
When switching to dim from the brights on my '94 GMC 1500 Z-71, the headlights go off momentarily then come back on. To begin with first I was having problems with the truck not going into Overdrive, then the Cruise Control went out. Now the truck won't go into OD at all and then the dimmer/bright switch with the headlights going out. Are these problems related? What could be causing this problem and how can I fix it? Thanking you in advance-Bill
Sunday, July 11th, 2010 AT 1:07 PM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It may be your dimmer switch if you have the one on the floor. Just disconnect it and pull the switch off the floor and clean it up clean the connector up as well. Also clean your battery cables as it maybe causing a problem as well. Have a trans guy look at the trans, he can scan it and see if there is an electrical problem.
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Sunday, July 11th, 2010 AT 3:41 PM
Tiny
BILL52
  • MEMBER
  • 2 POSTS
Thank you for your reply, but the dimmer switch is located on the Cruise Control. I thought that maybe the problems with Overdrive, the Cruise Control not working now and the the hesitation of the headlights when switching from dim to bright or back etc, could be related.?
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Monday, July 12th, 2010 AT 2:44 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It's hard to remember where teh dimmer switches are on older trucks. I would think that the cruise control and dimmer may be related but not the overdrive. That could be another elelctrical problem by teh transmission or the solenoid that activates it. Have a trans pro check the trans. You may have a bare wire in the steering column maybe causing your problem. It would have to be investigated to see wha the problem actually is. You might try checking for relays for the cruise and whether or notit's getting power or if it is being stopped by the brake light switch, as that kills the power to the cruise. It could also be a vacuum leak if yours uses vacuum.
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Monday, July 12th, 2010 AT 6:38 PM

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