Mitch Thompson

I just bought a 2002 Jeep GC. I noticed that the speedometer was off by about 10mph, and the tach was off as well by an equal amount.

When I initiate the gauge reset procedure (button hold down + key on), both gauges rotate to the 3 oclock position, before rotating back against the stop. Every reset process results in this. They never rotate to their maximum values. When I drive, the speedometer has no movement until about 10 mph, which at that point it begins to move. Additionally, the idle sits at roughly 100 - 200 rpm marker.

Has anyone encountered this? Do i just have to take my gauge's needles off and move them so when i do a reset it moves to the maximum position instead of being off by about 20 degrees of a circle?

Thanks guys.

Noah911

The only thing I can think of is to take the bezel off the cluster to expose the gauges. Start the Jeep. Hook up an OBD2 scan device and have it read the RPM. Try taking the RPM needle off and set it at the value you get from the scanner reading. See if it works normally from there on?

I think with the speed needle you can use an app on your phone and drive to 25mph, and set the speed needle there at 25mph on the gauge, might work?

dave1123

Both those gauges get their information from the PCM. I would suggest disconnecting the battery and touching the cables together to reset the PCM memory.

Noah911

With an OBDII scan tool you can set the rpm needle exact. Same with gps for speed.

Do they work normally otherwise, they are just miscalibrated at the gauge?

(edited):
Oil psi gauge with a mechanical oil psi tester.
Voltage with a scanner, or DVOM
Engine temp with a scanner, or infrared/FLIR
The fuel gauge needle is a tough one to set...

Noah911

I'm sure it's common knowledge, but in case you do not know? Holding down the trip button the whole time and turning the ignition key into the run position initiates a gauges test protocol. All six needle gauges swing from the far left to the far right and back again, before going to real-time readings of temp, voltage, etc...

I checked mine. The RPM and speedo needle both swing greater than 180* to the right going below the 7g's in the rpm, and below the 120mph dashes on the speedometer when I ran the test.

dave1123

If you had read his original post, he's already done that.

Noah911

I know. I saw his rpm and speed needles only go to the 3 oclock position when he initiates the gauges sweep check. I don't know why I explained the way to do the check? Maybe for another person reading who did not know.. I did the test on mine for comparison value of where the needles swing.

The needles can be put on wrong, or move..

Someone had the speed needle get stuck underneath the resting pin out of the blue. The speed never moved from zero.. No idea how it happened either, since the cover to the gauges had never been removed by him?

All of the gauges and their needles are controlled by pcm, sensors, etc... The needles know their positions based off different current. So many amperes at 12 oclock. So many more or less amps at 3 oclock, for the same needle. All the gauge needles are different in this regard.

I think it would be worth resetting the pcm with the battery cables to see? It could be electrical.

I read where a guy replaced the cluster. The new(er) cluster needles all read wacky. He cleaned all of the pins and connections and electrical contacts on the new cluster and wires/connectors. That fixed it. The needles were working normal afterwards.

dave1123

I had a similar thing happen with mine. First start in the morning, I turned on the key and both the speedo and tach went full scale and back to zero. I tried starting it, nothing but a click. I tried again and same thing happened. I saw the voltmeter sitting on 9 volts. I jumped it with a good battery and it fired right up, but both gauges were pegged out. I took off for the battery store with the other battery and the jumper cables just in case. The battery had an open cell connector inside it, so I had a new battery put in. It fired right up and both gauges acted normal. The old battery tested good, but if you tapped on the side of it, it went right to 9 volts. When it read 12.5 volts, a load test was good for about 20 seconds. All the way to the store, both gauges were pegged out at the top of their scales. They had just installed that battery about 6 month before this happened so I got a new one free.

Noah911

Definitely, the battery.. Or, terminals?

I know all three times my WJ would drop its electrical load while dealing with the crummy poor battery terminals.. both my fuel and the engine temperature gauges needles would go all of the way fully pegged to their maximum readings all of the way pointed to the right sides, and would stay there. Also though, both the fuel gauge and the engine temperature gauge needles would begin to start swinging wildly back n forth from their minimum to their maximum readings non-stop, depending on where I turned the ignition key too.