So a couple of months ago I plugged my cluster with the key in the acc position and that seemed to break my temp gauge.
I already had 2 more clusters with the same issue, particularly on all of mine, the temp gauge went to red-hot whenever the key was in the on position.
I didn't want to buy another cluster just for that, so I disassembled my cluster and went on to diagnose it a bit.
The temp gauge (and the fuel gauge almost equally) depend on the SI circuit. The SI circuit provides positive, negative and signal to the temp gauge (the fuel gauge uses positive and negative from the SI circuit or something similar, diagnosed this some time ago and memory is not my finest characteristic
).Ok, so, since I really couldn't care less about the SI part of the cluster (just as long as the lights go out when I turn it on), I decided I wanted to bypass those needed signals. On early clusters, with a separate SI board, it's much easier since it's modularized, on the later style clusters it's a single board with everything on it.
So on the next pictures I'll show which traces need to be cut and jumped:
Victim:
Disassembled:
Cut trace to positive on temp gauge:
Cut trace for temperature signal and bypass to gauge:
Now on the other side:
Desolder resistor and solder new jump wire for positive on fuel gauge:
Solder jump wire on positive terminal of fuel gauge:
Add jumper wire on negative terminal of temp gauge:
So with this modifications Fuel and Temp gauge will work regardless of SI circuit issues
Didn't modify tach nor fuel economy gauges since mine were working correctly, but similar mods will be needed if desired.
Hoping this fixes some clusters out there
Juan