BigFlo
Well-Known Member
Wanted to go through a cluster gauge problem I had. This is a 65 Belvedere off a fresh restomod. Gauge cluster had been out and placed into a new dash bezel.
Dash lights and oil pressure light were working. Gas and temp gauge were not working. Obvious choice is the voltage limiter, right? I had my original OEM limiter that hadn’t been powered for the past 30ish years so I figured it was bad - plus I wanted a new digital one, so I purchased one from Real Time Engineering . After installing the new limiter, the gauges still didn’t work. I removed the cluster, buzzed out all of my circuit board traces - ground and voltage paths were all good. All of my dash grounds were good. I reinstalled the cluster and had good grounds and 12v to the circuit board trace where the limiter plugs in. So I suspected the new limiter might be bad. RTE told me that you can’t test the limiter with a voltmeter - since it sends voltage pulses, it won’t give an accurate reading. (And I don’t have a scope). They said you can tell that the limiter is working if the LED lights up when powered. The LED was lighting up but I was not convinced it was working properly. I powered up my original mechanical limiter and saw the pulses on my voltmeter, so I knew that was at least working. I plugged it into the circuit board again and the gauges still didn’t work. This was a fresh rebuild with a new gas tank/sending unit and new temperature sending unit. The odds of both new sending units being bad is really low. I grounded the temperature sending wire and nothing happened. I obviously missed something in the cluster so back under the dash I go, doing contortions to get ohmmeter probes onto the circuit board. After buzzing everything out again, it all looked good. Damn!
I’m still missing something.
I had zero ohms from the gauge posts to those wonky stamped speed/pal nuts, so I know I had connection to gauges. But I finally I checked continuity from the pal nuts to the circuit board traces and they were open. Damn x2!
I took off the pal nuts and there was some kind of film that had developed between the circuit board traces and the nuts, causing the open circuit. I wiped the circuit board traces with degreaser and used Emory cloth on the nuts and reassembled - and the gauges worked.
Of all things to consider, this was unlikely because I had the gauges out (and had removed those pal nuts) several months before, when I replaced the dash bezel.
This took me several weekends of trial and error, removing the cluster, troubleshooting, etc, to fix one relatively minor issue. Maybe this helps someone down the road but it just shows what we all know - these unforeseen little things add so much time to our builds, but in the end, it’s worth it.
Dash lights and oil pressure light were working. Gas and temp gauge were not working. Obvious choice is the voltage limiter, right? I had my original OEM limiter that hadn’t been powered for the past 30ish years so I figured it was bad - plus I wanted a new digital one, so I purchased one from Real Time Engineering . After installing the new limiter, the gauges still didn’t work. I removed the cluster, buzzed out all of my circuit board traces - ground and voltage paths were all good. All of my dash grounds were good. I reinstalled the cluster and had good grounds and 12v to the circuit board trace where the limiter plugs in. So I suspected the new limiter might be bad. RTE told me that you can’t test the limiter with a voltmeter - since it sends voltage pulses, it won’t give an accurate reading. (And I don’t have a scope). They said you can tell that the limiter is working if the LED lights up when powered. The LED was lighting up but I was not convinced it was working properly. I powered up my original mechanical limiter and saw the pulses on my voltmeter, so I knew that was at least working. I plugged it into the circuit board again and the gauges still didn’t work. This was a fresh rebuild with a new gas tank/sending unit and new temperature sending unit. The odds of both new sending units being bad is really low. I grounded the temperature sending wire and nothing happened. I obviously missed something in the cluster so back under the dash I go, doing contortions to get ohmmeter probes onto the circuit board. After buzzing everything out again, it all looked good. Damn!
I’m still missing something.
I had zero ohms from the gauge posts to those wonky stamped speed/pal nuts, so I know I had connection to gauges. But I finally I checked continuity from the pal nuts to the circuit board traces and they were open. Damn x2!
I took off the pal nuts and there was some kind of film that had developed between the circuit board traces and the nuts, causing the open circuit. I wiped the circuit board traces with degreaser and used Emory cloth on the nuts and reassembled - and the gauges worked.
Of all things to consider, this was unlikely because I had the gauges out (and had removed those pal nuts) several months before, when I replaced the dash bezel.
This took me several weekends of trial and error, removing the cluster, troubleshooting, etc, to fix one relatively minor issue. Maybe this helps someone down the road but it just shows what we all know - these unforeseen little things add so much time to our builds, but in the end, it’s worth it.
