A common problem with the clusters in the 7th gen are the servos (aka stepper motors). The original servos are known to go bad pretty frequently. The symptoms include gauges not reading properly (such as reading 100mph when you're going 30), not seating properly (speedo sets at 30 when you turn the car off), and general erratic gauges.
If one of your gauges is acting up, you will need to replace the servo. You might as well replace all of the original servos while you have the cluster open, to avoid issues in the future. There are 3 types of clusters that came in the 7th gen, the 3 gauge in the base model, the 4 gauge in the Ls model, and the 6 gauge in the SS/LSS models. Each gauge has it's own servo, so make sure you buy enough.
In order to do this yourself, you have to be comfortable soldering on circuit boards. It's not hard to do, but it can be a little intimidating for the first timer. Make sure you have a 25w
soldering iron, or you risk damaging components on the circuit board.
GM re-engineered the part with a new part number (X27.168
). They can be found online (I bought off eBay) for about $5 each. DO NOT BUY THE BLACK STEPPER MOTORS
as they are made in China and are inferior in every way.
This is the style of servo you want to buy. Notice the part number on the bottom portion of the servo
I used this guide for disassembling the cluster:
Impala/Monte Carlo Cluster Bulb Conversion
From here, you'll have access to the circuit board to do your soldering.
Each servo has 4 contact points with the circuit board. Desolder and remove each servo, then put the new servos in their spot, with attention to their orientation on the circuit board. Solder the new servos in.
At this point, you can begin to re-assemble the cluster. The steps are the same, just in reverse. Before putting the needles back on, plug the cluster back into the car, and start it up. Let it reach normal operating temperature, and then place the needles in their respective slots, ensuring to point the gas needle to full, the temp needle to normal operating temp (about half way) and the speedometer needle at zero. Once that's done, you can finish reassembling the cluster, and reinstall it.
It sounds like a lot of work, but it's really not. It took me about two hours start to finish, and I was also replacing all the bulbs with LEDs.
*2001 Impala Ls - 131k
Precision 6262 Turbo, ZZP Z3, CXRacing intercooler, ZZP 3" Cat-back, Bosch 42.5# Injectors, Bosch fuel pump, CM front springs, Dorman solid sway bar, SPEC-D LED headlights, 8000k heads and fogs, Quad tails, C5 reverse lights, All LED interior, LED 6 gauge cluster retrofit, LED puddle lights, Debadged, Dipped emblems, Color-matched trim, Kenwood DDX271, Polk Audio dxi6500 components, Polk Audio db690, Hifonics GLX100.4, 2x Polk Audio db1240 in custom box, Hifonics ZRX1800.1D, 08 SS Wheels, SS tail covers, SS Lip, 35% tint, Black mesh grille
*2000 Blazer 4x4 - 174k
*1977 C10 - SOLD
*2014 Impala LT Limited - 35k
*1992 Caprice Wagon - Sold @ 195k