Need diagnosing light problem
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Joined: Dec 2008
Posts: 73
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From: Lancaster Pa
Need diagnosing light problem
Just this week I realized that when I turn my lights on manually, the fog lights and dash lights will not come on. With the lights on, I can press the fog light switch but nothing happens. With the lights on, I can not get the dash to illuminate (gauges). I have tried adjusting the light intensity with the **** on the left side of the dash panel. The strange part is when "Twilight mode" activates, the lights pop up(if not already on), the fog lights work, and the dash illuminates. All gauges work correctly with lights on or off.
The car is a 2000 Hatchback that I just bought a few months ago. I replaced the headunit(with a stock one from a 2003 Z06) last month, and I just washed the car this weekend. Dont know if any of that matters, just thought I would throw that in anyway.
Does it sound like a blown fuse or a bad connection? If so, any idea where?
Thank you in advance
The car is a 2000 Hatchback that I just bought a few months ago. I replaced the headunit(with a stock one from a 2003 Z06) last month, and I just washed the car this weekend. Dont know if any of that matters, just thought I would throw that in anyway.
Does it sound like a blown fuse or a bad connection? If so, any idea where?
Thank you in advance
Tech Contributor
Joined: Dec 2003
Posts: 19,384
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
It could indeed be the headlight switch thats the problem
The fact that the lights work OK in twilight sentinel mode but not in normal mode is understandable. The TS bypasses the headlight switch. If power is on the car and the TS senses an off signal from the headlight control if allows the headlamp control module to operate.
The fog lights are on a separate circuit which makes it difficult to understand. Check fuse #32 on the footwell panel. It routes from the switch to the tell tale, to relay 39 via fuse #6, to the fogs, to ground at G102.
The common fuse in all this is #6 on the passenger footwell panel so you should check that. The relays in the circuits are not common but its #39 for the foglights and #43 for the interior lights.
The only common thing in the whole problem is the ground. Try cleaning up G102 and G101 and see if you get anywhere.
What may explain it is if the headlight switch is fooling the circuit into thinking its turned off despite the fact you've selected it to parking lights or low beam position. If thats the case, the fogs would be inhibited and the dash lights would be off. Thats the symptoms you're getting.
Are there any DTCs on the DIC?
This may be one for the electrical guru Bill Curlee.
The fact that the lights work OK in twilight sentinel mode but not in normal mode is understandable. The TS bypasses the headlight switch. If power is on the car and the TS senses an off signal from the headlight control if allows the headlamp control module to operate.
The fog lights are on a separate circuit which makes it difficult to understand. Check fuse #32 on the footwell panel. It routes from the switch to the tell tale, to relay 39 via fuse #6, to the fogs, to ground at G102.
The common fuse in all this is #6 on the passenger footwell panel so you should check that. The relays in the circuits are not common but its #39 for the foglights and #43 for the interior lights.
The only common thing in the whole problem is the ground. Try cleaning up G102 and G101 and see if you get anywhere.
What may explain it is if the headlight switch is fooling the circuit into thinking its turned off despite the fact you've selected it to parking lights or low beam position. If thats the case, the fogs would be inhibited and the dash lights would be off. Thats the symptoms you're getting.
Are there any DTCs on the DIC?
This may be one for the electrical guru Bill Curlee.
Last edited by DeeGee; Mar 11, 2009 at 01:58 AM.
Thread Starter
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Joined: Dec 2008
Posts: 73
Likes: 1
From: Lancaster Pa
Thanks for the help. Does any one have a diagram that shows exactly where G101 and G102 are on the car? I do not have a service manual yet and the DVD on the forums will not install correctly for me.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Look in the sticky at the top of the Tech Forum area. The headlamp, fog lamp, fan grounds are located in the ground pack at the top of the forward right frame rail, adjacent to the hood riser.
8th Gear
Joined: Sep 2007
Posts: 8
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Twilight Option-off/on Problem
Have another lighting issue similar and maybe related. When the Twilght option is set to "ON" the lights pop up and the DIC goes blank for every button (was working fine till this week) . If I select the OPTIONS Button 10 or 15 times the Twilight resets to "OFF" and the DIC lights up again.
Any ideas?
Any ideas?
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
When the external lighting is on, the DIC brightness, HVAC and radio brightness are all controlled by the dimmer ****. When the external lights are off, the brightness is controlled by the light sensor that's located in the top of the DIC Controller. My light sensor went bad on me...
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Thread Starter
Advanced
Joined: Dec 2008
Posts: 73
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From: Lancaster Pa
Thanks for all the help and advice.
I took a look at the G101 and 102 connectors and they were ok. I took the car to church today and when I got back I decided to try the lights again. The drive back was only about 15 minutes, I pulled into the driveway and kept the engine running. I turned the right turn signal on and turned on the lights. THE FOG LIGHTS AND DASH LIGHTS CAME ON! Turned them off and on again and everything worked. Drove the car into into its spot, turned off the car and tried the lights again... no good. Tried again with ignition off, on, and restarted the car... nothing. Tried to turn the lights on with the right turn signal on, left turn signal on, and both off (in all ignition positions)... still nothing. This leads me to believe that the switch is going. Agree? And no it wasnt an act of God
Anyone ever replace one of these switches before? Any idea on the price of the switch? (with or without the "corvette tax")
I took a look at the G101 and 102 connectors and they were ok. I took the car to church today and when I got back I decided to try the lights again. The drive back was only about 15 minutes, I pulled into the driveway and kept the engine running. I turned the right turn signal on and turned on the lights. THE FOG LIGHTS AND DASH LIGHTS CAME ON! Turned them off and on again and everything worked. Drove the car into into its spot, turned off the car and tried the lights again... no good. Tried again with ignition off, on, and restarted the car... nothing. Tried to turn the lights on with the right turn signal on, left turn signal on, and both off (in all ignition positions)... still nothing. This leads me to believe that the switch is going. Agree? And no it wasnt an act of God
Anyone ever replace one of these switches before? Any idea on the price of the switch? (with or without the "corvette tax")
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
The headlamp switch can be replaced and you do not need to remove the steering wheel. Its fairly simple. You can also repair it if you wish by following Bill Curlee's advice in the electrical stick at the top of the tech section.
