1977 Guage cluster problem
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1977 Guage cluster problem
Having some trouble with my gauge cluster. 1977.
Replaced the PCB at the back of the cluster as some of the circuits were torn and not supplying power to the lamps and clocks. Works fine now, but when I turn up the lamps on the guages, every gauage lowers its readings quite a bit, almost like something is drawing power away. My first thought is that the lamps are not the right ratings, changed the bulbs, still have the same problem. Any one have any idea as to why?
One other problem, the memory wire to the radio, that is the yellow wire that supplies power regardless of ignition seems to be reading ~1 Volt, kind of odd as I don't see any breaks in the wiring.
If anyone has had a similar problem or anyone knows how I could resolve the symptoms above, would greatly appreciate the guidance or help.
Best,
-D
Replaced the PCB at the back of the cluster as some of the circuits were torn and not supplying power to the lamps and clocks. Works fine now, but when I turn up the lamps on the guages, every gauage lowers its readings quite a bit, almost like something is drawing power away. My first thought is that the lamps are not the right ratings, changed the bulbs, still have the same problem. Any one have any idea as to why?
One other problem, the memory wire to the radio, that is the yellow wire that supplies power regardless of ignition seems to be reading ~1 Volt, kind of odd as I don't see any breaks in the wiring.
If anyone has had a similar problem or anyone knows how I could resolve the symptoms above, would greatly appreciate the guidance or help.
Best,
-D
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I would lean toward a ground problem.The ground pin on the connector to the PCB may not be making a real good contact, or the other end of that ground wire.
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Joined: May 2006
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From: Dayton, Ohio
Its possible you might not have installed the printed circuit correctly. If I remeber right certain parts of the PC go to ground through the metal casing. If you have an insulating washer in the wrong location this might cause your problem. Go to Willcox's site and look for his instructions on how to install and check your work.
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As embarassing as this is, I caused my cluster to catch fire.
PCB was installed correctly - checked the wiring diagrams.
Felt this was a grounding problem so decided to test the two ground leads that connect to the PCB. Connected positive term of my voltmeter to red (12 V) lead and the negative term to the ground contact (tested both contacts) that hook into PCB, read 12 Volts as expected.
To test if it was grounded well, I connected negative lead of of voltmeter to negative terminal of battery and positive lead to the black ground wire on the radio, read 0 as expected. Then ran the same test on the ground contacts that hook to the insturment cluster PCB. Surprisingly read a fluctuating 3-6 volts (unless someone re-wired the car and used black wire for non grounded connections).
So, I tried a test, connected the ground contact to the chassis - it was reading 0 with my test, so that was good. Started the car and the little PCB with the lamp on the fuel indicator start to burn and was progressively getting worse. Took the ignition key out to stop the car - I then entered the twilight zone - engine kept running and fire was getting worse. So panicked, I disconnected the battery, darn engine still ran. Hammer to the fuel indicator PCB did the trick and cut the engine.
So now, I have a burned cluster and smashed PCB
I think the problem is with the contacts like TimAT said, but now have a much bigger project on hand unfortunately! All this to repair the clock and replace the radio!
PCB was installed correctly - checked the wiring diagrams.
Felt this was a grounding problem so decided to test the two ground leads that connect to the PCB. Connected positive term of my voltmeter to red (12 V) lead and the negative term to the ground contact (tested both contacts) that hook into PCB, read 12 Volts as expected.
To test if it was grounded well, I connected negative lead of of voltmeter to negative terminal of battery and positive lead to the black ground wire on the radio, read 0 as expected. Then ran the same test on the ground contacts that hook to the insturment cluster PCB. Surprisingly read a fluctuating 3-6 volts (unless someone re-wired the car and used black wire for non grounded connections).
So, I tried a test, connected the ground contact to the chassis - it was reading 0 with my test, so that was good. Started the car and the little PCB with the lamp on the fuel indicator start to burn and was progressively getting worse. Took the ignition key out to stop the car - I then entered the twilight zone - engine kept running and fire was getting worse. So panicked, I disconnected the battery, darn engine still ran. Hammer to the fuel indicator PCB did the trick and cut the engine.
So now, I have a burned cluster and smashed PCB
I think the problem is with the contacts like TimAT said, but now have a much bigger project on hand unfortunately! All this to repair the clock and replace the radio!
