C5 Headlights Inoperable

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Oct 16, 2012 | 03:31 PM

Tritrophy

Thread Starter

4th Gear

Joined: Oct 2012

Posts: 4

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From: Hillsboro OR

C5 Headlights Inoperable

I appreciate help and guidance to finish Headlight Trouble diagnosis.

During recent trip in our 2000 C5 FRC, I stopped the engine and opened door. Chime sounded and I turned off lights. When I returned and operated MFS, headlights did not pop-up and even after cranking them up manually they would not light.

I have tail lights, marker lights, interior lights, dash dimming, fog lights and front amber lights with key on and MFS turned to either Park or Headlights. I also do not have front amber lights with MFS to off.

I have checked all fuses under the hood, all are OK. In the footwell I have pulled Maxi-Breaker 54 and it has continuity. With MFS to ON there is 12V to one side of 54 breaker. I switched 44 Relay with 42 and Courtesy Lights still worked but headlights did not. I then pulled the relay from 44 position and checked. I had 12V at both terminals on one side. I had Ground at one and a resistance value of 1.75 at 25K Ohms range at the other.

I am stumped. Is the inconsistent reading on the Ground side of 44 telling me the BCM is my only possibility?

Thanks to you all, I have been reading the Forum and truly enjoy the helpful camaraderie.

Oct 16, 2012 | 04:08 PM

Tritrophy

Thread Starter

4th Gear

Joined: Oct 2012

Posts: 4

Likes: 0

From: Hillsboro OR

I will give it a go.
I presumed if I had power to the #54 Breaker the MFS was working.
Thanks.

Oct 17, 2012 | 12:19 AM

Tritrophy

Thread Starter

4th Gear

Joined: Oct 2012

Posts: 4

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From: Hillsboro OR

Thanks, your direction is much appreciated. I will tear into the MFS tomorrow.

Nov 4, 2012 | 04:01 PM

Crunchking

Instructor

Joined: Oct 2004

Posts: 134

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From: Arlington Texas

8vette7, need some help. We had to replace the horn pad on my 98 C5, and the windshield wiper switch. However, as part of that repair, the headlights popped up and would not go down. The doors will not pop open or close using the switch. It has been balky in the past so we replaced that switch. No change. If you manually crank the headlights down, when you disconnect and recoonect the battery - both headlights pop up whether the switch is turned on or not. It is like a gremlin. Any thoughts??

Nov 4, 2012 | 05:12 PM

CactusCat

Melting Slicks

Joined: Nov 2009

Posts: 2,922

Likes: 219

From: West Branch, MI

Was there any end result on this? Curious minds want to know.

Nov 4, 2012 | 05:46 PM

Tritrophy

Thread Starter

4th Gear

Joined: Oct 2012

Posts: 4

Likes: 0

From: Hillsboro OR

Thanks for all the good help. The R&R Remove & Replace went smoothly thanks to the great directions provided. I did not even try to repair the MFS, instead Amazon had them for $123 with free Prime shipping. The new switch fixed problems I did not know I had, so now I have Headlights AND Fog Lights which I expected had a grounding gremlin.
Here are Two Recommendations:
1. Definitely pull the console and the radio faces loose, it is only 6 fasteners.
2. Remove the metal guard behind the knee panel before you remove the column covers.
Thanks again for the good advice.

Nov 4, 2012 | 05:58 PM

Crunchking

Instructor

Joined: Oct 2004

Posts: 134

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From: Arlington Texas

Good News on yours. Anyone have any thoughts on my gremlin. I have replaced the switch and no change. The switch turns on all the lights, but will not operate the headlight doors. If I manually close the doors then disconnect the battery, the doors will open as soon as I retouch the battery cable whether the switch is on or not.

Nov 4, 2012 | 09:35 PM

CactusCat

Melting Slicks

Joined: Nov 2009

Posts: 2,922

Likes: 219

From: West Branch, MI

Quote:

Originally Posted by Crunchking

I'm going to take a stab and use some of my not-so-logical logic on this. It sounds to me that when you replaced the horn pad and windshield wiper switch, you have somehow put power to your headlight motor 100% of the time. They never completely "turn off" and are stuck in an eternal state of thinking they're always turned on. When you disconnect the battery, you "break" the link of being on 100% of the time and for further evidence of this state, as soon as you touch the cable to the battery (reconnecting) they pop up. That tells me that when you installed those two items, you shorted or crossed the wire to the headlight motors. Take the horn pad and windshield wiper switch out and see if they're back to normal. It's a PITA, I know but its the only logical conclusion, especially if the headlights worked properly before you replaced those two items.

Last edited by CactusCat; Nov 5, 2012 at 07:41 AM.