Author Topic: [Write-Up] How to replace stepper motors to fix gauge cluster (2004 Impala SS)  (Read 2676 times)

Kalgorn

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This is a problem that, from what I've read, affects 2003-2006 GM vehicles. They used a bad batch of stepper motors that have a very high rate of failure. When a stepper motor fails, the gauge continues to work but it doesn't reset to "zero" properly so the base point is different every time you start the car. I purchased the revised stepper motors on Amazon.com for $19 shipped.

This is not a very difficult repair to perform but you need to know how to desolder/solder. If you're not comfortable doing that, there are plenty of companies that will do the repair for you. One example is GaugePegged.com. The repair isn't terribly expensive but it will run you anywhere from $60-100 or more depending on which company you use, which repair you choose (some companies will replace the soldered gauge bulbs as well as other things), and how much the shipping is.

Tools needed:
- Soldering iron
- Solder
- Solder sucker/desoldering pump
- Rosin soldering flux (optional but highly recommended)
- Phillips screwdriver and/or 8/32" socket (I believe that was the size)

To start, the cluster needs to be removed from the car. I followed the instructions on NAIOA for removing the panel trim plate. Once the trim plate is off, there are four (4) screws securing the cluster. There is also a large electrical connector (green) that can be unplugged once the screws are removed and the cluster is partially removed.

Remove the cluster from the car.



Remove the plastic cover. There are a handful of clips securing it to the back plate. This step is self-explanatory once you have the cluster in your hands.

With the cover removed, you need to mark the "zero" point for each gauge. This point is found by very lightly rotating each gauge needle counter-clockwise until it stops. Do not push it past the stopping point or the marking will be innacurate. I used painter's tape and a pencil to mark the point for each gauge.



Remove all of the gauge needles using a fork. It will take a surprising amount of pressure but just be careful and don't gouge any of the gauges with the fork.



With the needles marked and removed, you need to separate the back plate from the gauges and circuit board. There are clips securing the back plate to the gauges. This is also self-explanatory once you have the cluster in your hands.

With the back plate removed, carefully separate the gauge face from the circuit board. There is a ribbon cable connecting the two pieces. Unplug the ribbon cable from the gauge faces.



You can now completely separate the two pieces. Set the gauge faces aside and focus on the circuit board. The white discs are the stepper motors. There is one for each gauge.



On the back of the circuit board, you can find the solder points for the stepper motors. There are four points for each motor.



The method I found easiest to remove the motors was to use a small pair of snips to cut off as much of the four posts as possible. Once they're cut off, I just heated each corner over and over again while lightly pulling on the stepper motor. It takes time but it works well. If you have a small tip for your soldering iron and a desoldering pump with a fine tip, you can probably heat each point and suck all of the solder off. My desoldering pump is bigger (I really should replace it) and I couldn't do that so I used the method I mentioned.

Once the stepper motor is removed, use the desoldering pump to clear out the holes in the circuit board. With the holes cleared out, you should be able to push the new stepper motor in. They fit pretty snugly due to the plastic alignment posts. I had to use some pressure to get them to seat properly. Be sure the new motor is flush with the circuit board before soldering the posts.

Here is all of the stepper motors replaced:



Once the motors are replaced, begin to reassemble the cluster.

Push on all of the needles at a 12:00 position (pointing up). Once the needles are on, turn each one counter-clockwise until you get to the stopping point I mentioned earlier. Once at that point, continue rotating counter-clockwise and push past the stopping point. You want to move that stopping point to the "zero" point that you marked for each gauge.

Once all of the needles are zeroed, leave the plastic front case off and put the cluster back in the car. Just sit the cluster on its plastic mounting points. You don't need to put the screws in. Make sure you plug in the connector for the cluster.

Start the car and verify that all of the gauges are working. Also attempt to verify that the gauges are as accurate as possible. I filled up my gas tank before performing this repair so I know that if the gauge is showing full, it's working properly.

Once you've verified that the gauges are accurate, pull it back out of the car, install the plastic front case, and reassemble everything back in the car.

2002 Silverado | 1995 Talon TSi AWD | 1989 Prelude Si 4WS

maxharvard

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Mind if I repost this on my site?

gearheaddaily.com

Turd Ferguson

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We are having some problems with a 2005 impala at work right now. Just not sure if it has anything to do with this same stepper motor issue. We replaced some of the common cooling system parts that leak on these gm motors. Customer drove the car to seattle (about 250 miles) with everything fine. Went to come back home from Seattle and randomly the temp gauge shot up past the end  of the where the gauge reads. She pulled over and shut the car off. Then felt the hoses and they were hot (like operating temp,not touch and immediately pull your hand off) got back in the car started it up and it was fine. Have you heard of similar situations that pertained to the same stepper motor issues?

Kalgorn

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Yeah, when they start to fail, they work intermittently. Once a motor completely fails, it never shows the proper reading. When I bought my Impala, the gas gauge would usually work but not always. Temp gauge and tach were completely failed.

I wouldn't go replacing anything on a whim though. It could be the coolant temp sensor. I'm just assuming that could make the temp read high.
« Last Edit: December 17, 2014, 01:12:00 PM by Kalgorn »

2002 Silverado | 1995 Talon TSi AWD | 1989 Prelude Si 4WS

Onyx Dragon

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Awesome write up!