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My speedometer ethier says that Iam going slower then I am or sometimes doesn't work at all and other times its fine. Took to a mechanic and they said that they don't know whats wrong with it and to take it to a gm dealership and they would have to take apart the instrument cluster. also is you have any guides or anything about how to take it apart please share. Tried to find a haynes magazine but no one around here has one. Just wondering if someone has had this problem or if someone knows how to fix it or what it might be. Thanks for you time.
 
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dont start with the dash board!! the sensor plug on the side of the trans may be either loose dirty etc. think about it the instrument cluster is protected inside the car from the elements but the trans area is experiancing everything the road had to throw at it (litterally) heres a basic explanation of the speedo system and design. inside the transmission is a gear that is meant to connect to a plastic gear with teath count calibrated to your cars final drive ratio. the plastic gear used to be installed on the end of a cable the cable was six sided shaped and inside of a protective flexible tube. the cable went to the back of your speedo head and plugged into a socket with the same 6 points. this moved the speedo and odemter when you rolled in gear. the new design sends an Electronic signal from a similar gear in the side of the trans. the electrical signal is sent threw the E>C>M. and on to the speedo head then converted to either a mechanical needle or digital number.
 

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If its just your speedometer that's geeking out, I would start with the output speed sensor (vehicle speed sensor) on the trans, that's alot cheaper. But there is most definitely a good chance that the instrument cluster is geeking out.
 

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My speedometer ethier says that Iam going slower then I am or sometimes doesn't work at all and other times its fine. Took to a mechanic and they said that they don't know whats wrong with it and to take it to a gm dealership and they would have to take apart the instrument cluster. also is you have any guides or anything about how to take it apart please share. Tried to find a haynes magazine but no one around here has one. Just wondering if someone has had this problem or if someone knows how to fix it or what it might be. Thanks for you time.
I have had a similar problem. The instrumentation in the impala's have a known history of issues.

Try this.

When your speedo or other instruments are not working.
1) Stop and shut car off
2) With the vehicle off, put it into R (reverse)
3) Attempt to start car a few times (the car wont start in reverse)

This should resync your gauges.
 

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I have had a similar problem. The instrumentation in the impala's have a known history of issues.

Try this.

When your speedo or other instruments are not working.
1) Stop and shut car off
2) With the vehicle off, put it into R (reverse)
3) Attempt to start car a few times (the car wont start in reverse)

This should resync your gauges.

I'll have to try this in my 04 Envoy, does the same thing, i can hear the speedo clicking , trying to move but its @ 80mph in park :mad:

I know they have an isse w/ the clusters
 

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Here are two posts I stole from other sites. Not really vehicle specific but GM specific.

Impala LS 3.4L V6
Automatic transmission 23,500 miles It is my mom's car. The speedometer kept going up even when you were slowing down. The Chevrolet dealer was going to charge her $90 to remove the instrument cluster, $350 to send the cluster out to be "rebuilt" (stepper motor replaced) and $90 to reinstall the cluster. I researched it and found out that the stepper motor is the same one for all the gauges, so if you only replace one eventually the others will go, so if you are replacing one, just replace all of them. I went to ebay and bought the updated x 25 168 stepper motors and removed the bad stepper motor (x c5 168 OEM) and soldered in the new updated one.

It was a 2 man job but fairly easy fix. I can't believe the price that I have heard other people was quoted (up to $800). It took longer to remove the instrument cluster from the car than it did to replace the stepper motor.


Sorry – no pics. My son had my camera out of town on a Boy Scout event. When time permits I will take an hour and do pics for this article.
The pointers on the gauges in the instrument cluster are operated by stepper motors, which are driven by the cluster logic. The stepper motors are a common failure. My oil pressure gauge went erratic then stopped at the high end even with the engine off. A scan tool told me the sensor was working and the PCM knew the real oil pressure; this narrowed things down.

When this happens you have some choices:

1. The Dealer Man wanted over $500 for a new cluster with R&R and programming the cluster with vehicle mileage and engine hours.
2. There are some people advertising cluster repair on eBay. This requires pulling your cluster, shipping it, getting it repaired, then shipping it back. I have been told the truck will run fine without the cluster, but then you get to guess things like speed and what gear you are in.
3. Replace the bad stepper motor yourself. I got one on eBay for $15 plus shipping from charlieboats08.
(update 6/20/09: Bought one for fuel level gauge from mandigital this week. Great price, very fast ship)
Materials:
1. One or more stepper motors.
2. Fine rosin core solder

Tools:
1. Desoldering tool. There are several types. Some are “suckers” that you use with a soldering iron to pull the solder out of the joint. The one I used is from Radio Shack for about $11. It is a 45 watt soldering iron with a hole in the tip and a rubber sucker bulb.
2. Soldering iron. About 25 watts is good for this job.
3. 7 mm nut driver or equivalent.
4. A small flat blade screwdriver.
5. A kitchen fork. (yes, details later).

Procedure:
1. Set the parking brake. If it doesn’t work, block a wheel.
2. Turn the key on and pull the shift down to “1”. Chime goes “ding ding …”
3. Pull the tilt wheel all the way down.
4. Pull off the dash bezel. It uses spring retainers so pull it straight back.
5. Take out the 4 screws (7 mm head) that hold the cluster in.
6. Work the cluster back. Release the electrical connector at the top back of the cluster by releasing the retainer. Unplug the connector.
7. Remove the cluster. It’s a bit of a squeeze between the top of the dash and the shroud thing on the steering, but it will come out without breaking anything. Honest.
8. Take the cluster to your clean, well lit work space. Plug in the desoldering tool and soldering iron to heat up.
9. Take the back off the (black) cluster by using your small screw driver releasing the lock tabs that hold it to the (white) frame part. You are now looking at the back of the cluster PC board.
10. Take off the front lens/bezel assembly. It has lock tabs at the top and bottom to hold it to the white part. The top ones are easy with a small screw driver. The bottom ones are a bit of a bitch. Mild cursing helps.
11. The PC board is now being held in by the gauge needles. You have to remove all the needles even if you are only working one stepper motor. The guy who sold me the stepper motor provided directions to get the needles back on pointed to the right reading but I got it wrong. More later.
12. Twist each needle a little counter clockwise to break the bond between the needle and the stepper motor. Use the kitchen fork to lift off the needle. No need for a 10 ton porta-power.
13. The circuit board will now come out. Be REALLY SURE you pull the stepper motor you want to replace. Maybe mark it with a Sharpie.
14. There are 4 pins that come out of the back of the stepper motor and are soldered into the PC board. Take your now hot desoldering tool, squeeze the bulb while NOT pointed at the PC board. (We want suck, not blow.) Melt the solder and suck it up. Repeat for each of the 4 pins.
15. The motor should now be easy to pull off.
16. Put the new motor in its place. There are locator pins. Make sure it is flush against the PC board.
17. Take your soldering iron. Make sure the tip is clean and tinned. Solder each pin to the PC board. Heat the board pad and the wire; then let those parts melt the solder. Don’t try to melt the solder on the iron then try to dab it in. That doesn’t work.
18. Examine your solder joints carefully. They should be smooth and shiny, flowed onto the pad and the wire.
19. Unplug your soldering iron and desoldering tool. If you are lucky they will cool off before you accidentally grab the wrong end of one.
20. Place the PC board back in the middle (white plastic) frame. Put the back cover on, press the retainers down until they lock.
21. Replace the instrument needles. The guy that sold me the stepper motor recommended pushing the needle on pointing at mid scale, then twisting to the bottom of the scale. Try it, but this didn’t work out for me; maybe I didn’t understand correctly. Hence:
22. DO NOT PUT THE FRONT LENS PART ON YET. More later.
23. Put the cluster (less the front lens) back in the truck, with the cable plugged in. Don’t put in the screws yet.
24. Start the truck. Oh, shyte, no start. Oh, I’m in first gear. Neutral safety switch. Put it in park and really start it this time. Watch the gauges come to life. In my case some were reading really whack.
25. Shut off the truck. For each gauge that is not reading bottom of scale, pull the needle off and put it back in pointing at bottom of scale. Repeat this step a few times until you have it all right.
26. NOW put the front lens back on your cluster. You can do this with the back part of the cluster in the dash. Push until the locks click.
27. Put back the 4 retaining screws and the dash bezel.
28. Take the $500 you just saved and buy something you really wanted.
 

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Hey guys... My dad has an 04 Impala and is having this problem.

He has the original tire/rim size on the car and his tire pressures are correct.

did anyone ever try these fixes and did they work. I am going to try diagnose his car and fix it and just want a good place to start.
 
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