Replacing cluster gauges

[evilunclegrimace]

I recently had to replace my cluster and that involved changing the printed circuit for the speedo. I had to remove all of the needles and do not remember the procedure for reinstalling them so they read correctly. Anyone know the proper procedure?

 

[someotherguy]

Head-scratcher.. could you give more info on why you also did the circuit board if you replaced the cluster?

Setting the needles can be tricky, especially if you don't know what the original position was when you pulled them. Also I'd guess the older air core style gauge motors might move as you move the cluster around.

When I had to set needles on a GMT400 cluster (scored a 1992-1993 454SS cluster for my '94 years ago) it was because someone had pulled them all presumably to do one of those gauge face swaps, and put it back afterwards. All of them were wrong. I set them all by pulling the lens, installing the cluster to operate it, and setting all the needles based on actual measurements (voltmeter at battery, IR temp gun at thermostat housing/engine warmed up, oil pressure mechanical gauge, external diag tach, GPS for speedo.) The only one that had to be guessed at was the fuel gauge though you could get it close with an ohmmeter. Fill the tank and set it on "full" then when it gets down to half, fill the truck up again and see how many gallons it takes - divide tank capacity by half and see how close you got. When it gets down to empty, before it runs out and croaks, fill it and see again how many gallons, and you'll have an idea of your "safety net" capacity before dead empty.

Richard

 

[evilunclegrimace]

Head-scratcher.. could you give more info on why you also did the circuit board if you replaced the cluster?

Setting the needles can be tricky, especially if you don't know what the original position was when you pulled them. Also I'd guess the older air core style gauge motors might move as you move the cluster around.

When I had to set needles on a GMT400 cluster (scored a 1992-1993 454SS cluster for my '94 years ago) it was because someone had pulled them all presumably to do one of those gauge face swaps, and put it back afterwards. All of them were wrong. I set them all by pulling the lens, installing the cluster to operate it, and setting all the needles based on actual measurements (voltmeter at battery, IR temp gun at thermostat housing/engine warmed up, oil pressure mechanical gauge, external diag tach, GPS for speedo.) The only one that had to be guessed at was the fuel gauge though you could get it close with an ohmmeter. Fill the tank and set it on "full" then when it gets down to half, fill the truck up again and see how many gallons it takes - divide tank capacity by half and see how close you got. When it gets down to empty, before it runs out and croaks, fill it and see again how many gallons, and you'll have an idea of your "safety net" capacity before dead empty.

Richard

There is a small circuit board on the lower right side of the cluster housing behind the instrument face, the speedo was not operating correctly on the replacement cluster so I swapped the known good part into the replacement cluster. ( it was going full sweep and pinning over 85mph)
What you described for the needles is what I am currently doing, I could not remember if there was a faster way of setting them to read correctly.
I hooked my "brick" up to the truck and put it road test mode to set the speedo, ammeter and temp gauges. I will run the truck over and fill the tank a set the fuel gauge needle accordingly. Thanks for the reply.

 

[someotherguy]

Using the Brick is a good approach but the readings will only be as good as the sensors are reporting. If your CTS is getting a little old, or there's any resistance in the grounds, your readings will be off. Voltage test right at the battery with engine running will be more accurate, and IR therm reading right at the thermostat housing with engine fully warmed up will be more accurate, too. GPS for the speedo will get you closer than what the DRAC is reporting since it's just doing calculations based on VSS pulses and the DRAC configuration.

Richard