Gauge cluster lights issue
Thread Starter
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
Gauge cluster lights issue
Need help or advice for my 1980. I have replaced all bulbs, sockets, and printed circuit in both speedometer/cluster and center gauge cluster. The speedo and tach light up like a Christmas tree. On the bench the lights in the cluster come on when power and ground is supplied to to right tab on the plug receptacle. There is power and ground at the plug in the car. However, no lights when the cluster is plugged in but the clock runs. I have tested, checked and retested every possible scenario that I can imagine. Even though I have power at the plug without plugging the speedometer housing in does it have to be plugged in for the cluster lights to work? I haven't connected the "flood light" at the top of the cluster but it appears to be independently grounded and power supplied and does not connect to the cluster printed circuit.
The dimmer on the headlight switch is in the proper position and it appears that the headlight switch, which is new is working since the other dash lights come on.
Anyone else had this or similar experience? Any advice or suggestions will be greatly appreciated.
The dimmer on the headlight switch is in the proper position and it appears that the headlight switch, which is new is working since the other dash lights come on.
Anyone else had this or similar experience? Any advice or suggestions will be greatly appreciated.
Last edited by nearflack; Feb 12, 2020 at 11:03 AM.
Burning Brakes
Joined: May 2013
Posts: 789
Likes: 129
From: Los Banos CA
When you say you have 'power at the plug' - are you referring to having power on the pin for the lights (when the lights are 'on'), or power to the connector that goes to the clock? Just asking since you mention the clock is working, which is on a different 'pin' than the lights. In theory, if you have power on the 'lamp' pin, and ground, and the cluster lights up on the bench, then it should work when connected in the car. Unless the connector isn't seating properly into the gauge cluster?
Melting Slicks
Joined: May 2015
Posts: 2,365
Likes: 428
From: Cape Girardeau Missouri
While I believe the replacement printed circuits are actually superior to the originals they are significantly thinner. That caused a problem with the low fuel module in my '79 and I used a piece of pasteboard (backing of a notepad) behind the printed circuit to keep the module firmly in place.
In that vein I suggest using some rubber cement to glue something like pasteboard to the back of the printed circuit where it "turns the corner" into the metal body where the connector plugs in.
In that vein I suggest using some rubber cement to glue something like pasteboard to the back of the printed circuit where it "turns the corner" into the metal body where the connector plugs in.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
Yes i am talking about the hot pin at the top of the connector that goes into back of cluster that has power when light switch is on. Power is constant at th clock pin-as it should be. I believe I may have it ran down to a ground pin problem. Using an ohm meter continuity isn’t constant and the gauges seem to work properly wit engine running until I pull the light switch on then the drop yo zero. It may be losing ground when I plug it in. Are all 3 of black ground wires in the connector wired to the same grounding point? I think I read there is one on the left front near the radiator which would be a likely spot for corrosion. I plan to run a ground direct from the connector tomorrow to see if that changes anything.
Burning Brakes
Joined: May 2013
Posts: 789
Likes: 129
From: Los Banos CA
Thread Starter
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
Need help or advice for my 1980. I have replaced all bulbs, sockets, and printed circuit in both speedometer/cluster and center gauge cluster. The speedo and tach light up like a Christmas tree. On the bench the lights in the cluster come on when power and ground is supplied to to right tab on the plug receptacle. There is power and ground at the plug in the car. However, no lights when the cluster is plugged in but the clock runs. I have tested, checked and retested every possible scenario that I can imagine. Even though I have power at the plug without plugging the speedometer housing in does it have to be plugged in for the cluster lights to work? I haven't connected the "flood light" at the top of the cluster but it appears to be independently grounded and power supplied and does not connect to the cluster printed circuit.
The dimmer on the headlight switch is in the proper position and it appears that the headlight switch, which is new is working since the other dash lights come on.
Anyone else had this or similar experience? Any advice or suggestions will be greatly appreciated.
The dimmer on the headlight switch is in the proper position and it appears that the headlight switch, which is new is working since the other dash lights come on.
Anyone else had this or similar experience? Any advice or suggestions will be greatly appreciated.
Thread Starter
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
Mainly a ground issue i believe although I did several different things. The main battery ground was corroded where it bolted to the frame. I replaced it and cleaned the ground on the pillar post. One or both appeared to solve the problem. Still have temp gauge but believe its a bad gauge not ground.
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