About 5 years ago I pulled the instrument cluster to add red LED back lights. Problem happened when pulling needles off. To this day I have the water temp and speedo messed up. Water temp doesn't move. It sits all way at far left (100* I think) and my speedo is roughly 30 mph too slow. It only starts increasing after hitting roughly 30mph where it then will climb proportionately. Ex: it'll show 40mph when going 70mph, still the 30 mosh difference.
Is there a correct way to fix these? If I pull the cluster, how do I fix the needles, how would I know if they're right without driving it?
I know this is an old post but I wonder if you're the same guy I talked to before that pulled the needles to do LED's. Because I can't figure out why anybody would pull the needles to do this, since the cluster comes apart with zero need to pull the needles. Anyway, horse is out of that barn, so on to the fix for anybody else reading:
As mentioned before, reinstall the cluster with the clear face removed, so you can access the needles.
Speedometer can be set via GPS as mentioned by other posters. Obviously you want to be real careful doing this since you need to be moving...
Tach can be set using an actual diagnostic tachometer hooked up to the engine, via the tach test lead on a TBI engine (single white terminal off the coil harness), or from scanner reading via OBD2 port 1996-up (cheap method is mini-ELM327 bluetooth adapter and Torque Pro app on your smartphone)
Oil pressure can be set using a mechanical gauge temporarily attached to the engine. You could just ballpark it at what you remember your normal reading to be, but this is a great opportunity to accurize your gauge.
Temperature should be read on a fully warmed up engine, using an IR thermometer aimed at the intake below the thermostat. With a 195° thermostat you should find a reading very close to that.
Volts should be right at 14 with engine running and all accessories & lights off, but confirm this so you know charging system is up to par, by reading it at the battery with a voltmeter. 13.9~14.1 is normal with engine running.
Fuel gauge set to full with a full tank, run it down to right at half, and fill up again - compare what it took to fill it vs. half your tank capacity; shortbeds have 25 gallon, longbeds get 34.
I had to go through this when I bought an SS cluster for my truck, where someone had done a gauge face change and just stuck the needles back on wherever. It read 70mph at a dead standstill and everything was off, too...
Richard
