I just put a 145 cluster in my car and I am having problems with a few gauges. The coolant gauge is reading fine and everything but every now and then it will stop reading and the needle will go down all the way. A second later it will read the temperature again. Other times the needle will keep going up and down real quick.
The gas gauge also "floats" up and down all the time. What could be the problem with these gauges.

 

Sorry, no real help. These kinds of electrical issues, however, are why I always recommend swapping the 145 speedo head into the original cluster--if the original cluster functioned as designed.

JamesC

 

Make sure the two 10mm nuts at the bottom of the cluster(look into the warning light pockets) are not loose.Even a little looseness will cause the gauges to fluctuate.If thats not it, maybe the connections to the dash.Thats all i can think it might be.

 

check the body grounds. if the gound wire contacts are kinda rusty it can cause you to have intermittent loss of signal wire.

 

I ended up just changing the gas gauge to fix that problem. For the coolant gauge, I found that I forgot to put the two nuts in at the bottom of the cluster. thanks