Barrman
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Warthog has a USAF Suburban that my class has been messing with for a while to bring up to running condition. Besides all the normal mechanical stuff. There has always been a problem with the front running lights.
They didn't work, ever. The side blinkers would work, which is the same bulb getting power down the same wire, but that light wouldn't work as a running light. The front blinkers would work very dim, but work with the lights off. Lights on and they were dimmer and slower. No matter the light switch position, the marker lights never worked in front. All was good in the rear. All good with the headlights too.
Warthog had a close, but not the same problem with another Suburban a few months back that are talked about in this thread:
http://www.steelsoldiers.com/cucv/62523-headlight-grounding.html
We checked those ground wires, checked the valence to frame ground wire, replaced the light switch and even pulled the plug off the back of the fuse block to check power getting through it. We were not able to hot wire the marker lights through that plug though.
With the bulbs out, a test light showed power to the sockets. However, the ground wire was solid and went right to a cleaned good ground. It was a real mystery that we just left alone since they kind of worked and moved onto other stuff.
I have started driving the truck around to see what else in this 25 year old very little use vehicle is going to wake up and decide to break. I decided it should get a road test by going 120 miles round trip to the monthly LSMVPA meeting tomorrow night. That means driving through Austin. Which means the lights need to be right.
So, Colton and I took another swing at it last night at home. Actually, one of the headlights went yellow and mysteriously got water in it seemingly over night since we haven't had rain in forever. We had the light cover off to swap in a new headlight and I just went ahead with pulling the blinker housing too.
Marker lights on at the switch, both blinker indicator lights lit on at the dash, rear lights on and nothing out of all 4 front marker lights. We started by testing the bulb and it worked on both lugs. Test light to the contact in the housing showed power to it. Following the ground wire showed it connected and good.
I ran a jumper wire from the negative battery terminal to the metal on the bulb and it lit up. So did the fender mounted side light on that side of the truck. It was a ground problem. I cut the ground wire and before adding in a new one, tested it again by grounding that wire. No light. The problem must be in the housing.
I didn't get any pictures last night because it was dark and my phone doesn't have a flash. However, here is the socket housing:
1982-1991 GMC G3500 Bulb Socket - AC Delco LS8
Notice that the housing is all plastic? I looked and couldn't see any metal in there at all for a ground. There was a black strip up one side. I used the test light probe to try and bend it over a little. It broke off about half way up. Behind the part that broke was a strip of metal. I just bent that over and down. Now the light had something to ground on. Both lights on that side now worked as running lights and bright blinkers. Blinker indicator light on the dash went off as well. Same problem and same fix on the other side.
This is the exact same housing as the CUCV trucks have. I have read several threads where people have wierd light issues with CUCV's. I probably replied to a few of them by saying "Check your grounds." Just don't stop checking until you get to the bulb like I did.
Oh, something else re learned that I should have trusted from way back when. A GM truck with a lit up blinker indicator light when the lights are on means there is a bad bulb or bad ground somewhere in the blinker system. Turn on the lights and anything not lit up is probably a good place to start.
They didn't work, ever. The side blinkers would work, which is the same bulb getting power down the same wire, but that light wouldn't work as a running light. The front blinkers would work very dim, but work with the lights off. Lights on and they were dimmer and slower. No matter the light switch position, the marker lights never worked in front. All was good in the rear. All good with the headlights too.
Warthog had a close, but not the same problem with another Suburban a few months back that are talked about in this thread:
http://www.steelsoldiers.com/cucv/62523-headlight-grounding.html
We checked those ground wires, checked the valence to frame ground wire, replaced the light switch and even pulled the plug off the back of the fuse block to check power getting through it. We were not able to hot wire the marker lights through that plug though.
With the bulbs out, a test light showed power to the sockets. However, the ground wire was solid and went right to a cleaned good ground. It was a real mystery that we just left alone since they kind of worked and moved onto other stuff.
I have started driving the truck around to see what else in this 25 year old very little use vehicle is going to wake up and decide to break. I decided it should get a road test by going 120 miles round trip to the monthly LSMVPA meeting tomorrow night. That means driving through Austin. Which means the lights need to be right.
So, Colton and I took another swing at it last night at home. Actually, one of the headlights went yellow and mysteriously got water in it seemingly over night since we haven't had rain in forever. We had the light cover off to swap in a new headlight and I just went ahead with pulling the blinker housing too.
Marker lights on at the switch, both blinker indicator lights lit on at the dash, rear lights on and nothing out of all 4 front marker lights. We started by testing the bulb and it worked on both lugs. Test light to the contact in the housing showed power to it. Following the ground wire showed it connected and good.
I ran a jumper wire from the negative battery terminal to the metal on the bulb and it lit up. So did the fender mounted side light on that side of the truck. It was a ground problem. I cut the ground wire and before adding in a new one, tested it again by grounding that wire. No light. The problem must be in the housing.
I didn't get any pictures last night because it was dark and my phone doesn't have a flash. However, here is the socket housing:
1982-1991 GMC G3500 Bulb Socket - AC Delco LS8
Notice that the housing is all plastic? I looked and couldn't see any metal in there at all for a ground. There was a black strip up one side. I used the test light probe to try and bend it over a little. It broke off about half way up. Behind the part that broke was a strip of metal. I just bent that over and down. Now the light had something to ground on. Both lights on that side now worked as running lights and bright blinkers. Blinker indicator light on the dash went off as well. Same problem and same fix on the other side.
This is the exact same housing as the CUCV trucks have. I have read several threads where people have wierd light issues with CUCV's. I probably replied to a few of them by saying "Check your grounds." Just don't stop checking until you get to the bulb like I did.
Oh, something else re learned that I should have trusted from way back when. A GM truck with a lit up blinker indicator light when the lights are on means there is a bad bulb or bad ground somewhere in the blinker system. Turn on the lights and anything not lit up is probably a good place to start.
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