Tip & How-To about Cars & Trucks

Intermittent electrical auto light issues

If your dimmer switch is on the floor and you are having high beam-low beam and/or turn signal glitches--there is a good chance that the connections on the dimmer switch have gotten wet and corrosion is causing random shorts--this was a common problem with floor mount and it is crazy how much weird stuff that can cause with your lights-- just remove and clean contacts with wire brush - be sure to remove ALL corrosion - then reinstall - they are inexpensive so it is just as easy to replace.

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2007 chev sub head lights wont turn on


Do you know anything about automotive electronics ? Electronic control modules .
Headlamp ON/OFF control is determined by the body control module (BCM) by a signal on the headlamp switch on input circuit when the headlamp switch is in the HEAD position. When the headlamp switch is in the AUTO position, the BCM determines headlamps ON/OFF by the voltage from the ambient light sensor.
If the headlight switch is left in the ON position, the inadvertent power control feature will turn OFF the headlights approximately 10 minutes after the ignition switch is turned to the OFF position. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, or if the ignition switch is in the ACCY position, the headlights will remain ON until turned OFF or the battery runs dead.
The high beam indicator is illuminated when the instrument cluster receives a GMLAN serial data message from the BCM that the high beams are illuminated.
High Beams
The high beam headlamps receive voltage from the headlamp high relay located in the underhood fuse block. The BCM controls the relay on the headlamp high beam relay control circuit. High beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is grounded, the BCM grounds the headlamp high beam relay control circuit, illuminating the high beam headlamps. The right and left high beam circuits are independent and are fused independently in the underhood fuse block.
Low Beams - Standard
The low beam headlamps receive voltage from the headlamp low beam relay located in the underhood fuse block. The BCM controls the relay on the headlamp low beam relay control circuit. Low beam control is determined by a signal on the headlamp dimmer switch signal circuit from the multifunction switch. When the headlamp dimmer switch signal circuit is open, the BCM grounds the headlamp low beam relay control circuit, illuminating the low beam headlamps. The right and left low beam circuits are independent are fused independently in the underhood fuse block.

Hooking up a factory scan tool an checking DTC'S - diagnostic trouble codes would be the very first step in trouble shooting this problem .
DTC B257A 00: Headlamp Switch Input Signal Mismatch
DTC 2575 00: Headlamp Control Circuit

Jun 30, 2017 | Cars & Trucks

1 Answer

2006 buick lacrosse low beams not working high beams only is i hold in the turn signal


this sounds like a bad dimmer switch not functioning. I would first check to make sure the rod that runs from the lever to the dimmer switch is traveling the complete length and is not out of adjustment.

Sep 28, 2014 | 2006 Buick LaCrosse

1 Answer

1996 dodge Ram 1500 4x4 headlights dont work.All other lights work. Headlight lamps are all good. Could it be the switch or the multifunction switch? High beam works when I pull on the directional le


The headlight switch gets power for the headlights from a 50amp fuse.
The fuse powers the headlight switch then the dimmer switch breaks for high and low beams. So if the high beams work, the problem may be with the dimmer switch.
The dimmer switch is made into the turn signal switch on the column. You would need to check the low and high beam circuits at the switch for power.

Jan 14, 2013 | Dodge Pickup Cars & Trucks

1 Answer

low beams arent working


check your dimmer switch on the colum or on floor which ever you have

Jul 11, 2012 | 1989 Oldsmobile Cutlass Ciera

1 Answer

I have a 1996 chevy 3500 p/u. No high beams or indicator light.


You dimmer switch needs replaced inside the stering column.

Sep 14, 2009 | Chevrolet 3500 Cars & Trucks

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