97 Chevy 1500 speedometer / fuel guage issues

[Tpotter1100]

Hello,
I am purchasing a 97 Chevy 1500 and during a test drive i noticed that the speedometer goes from zero to 100 extremely fast. in traffic in a 45 mile zone i was pegged at 100. as you slow down it comes down and will rest on zero at complete stop. (at least from what i remember) I will confirm once i purchase on Thursday) This is my first Chevy and i'm curious at how these instrument clusters operate. is it a sensor, or cable, digital/mechanical? The fuel gauge bounces all over the place as well. could that be a separate issue?

I'm curious as to what to test and what to look for.

Thanks in advance for the help and advice.

[sntrym95]

They are both electronic. The speedometer gets a signal from the ECM, which gets it from the speed sensor in the transmission. The fuel gauge gets its reading directly from the sending unit in the fuel tank.

The clusters are notorious for having the stepper motors go bad, but at $300 to fix them I wouldn't just replace it first. You can try 2 things:

1. Junkyard cluster - crapshoot, but you might find one in decent shape that works. At least you'll know if the original is bad.
2. Hook up a scanner to the ODBII connector that can read all of the info. If the speed at the ECM is correct, then it's your gauge.

[Tpotter1100]

Thanks for the response!
Wow, $300 is that for parts? or is that quoted labor/parts if i send it to someone? I'm not afraid to solder new step motors if need be, but I like the idea of the junkyard finds first.

Being that it is a 97, what years and version of 1500 trucks are compatible? (silverado, c/k, cheyenne, 1500, etc.)

I know this group is from 88-98 or whatever, but i'm sure only certain years are cool with certain years. at least that's my assumption.

Thanks for the help!

[sntrym95]

$300 is to send it out to get fixed, like through Electra-Sound. I'm sure you can find cheaper if you looked around. At the junkyard they are typically $25-30. Mileage will vary.

As far as I know, 96-99 will work, but don't quote me on that.