2003 Chevy Suburban speedometer

JUDDRAY

MEMBER
2003 CHEVROLET SUBURBAN
V8
2WD
AUTOMATIC
148,552 MILES

Speedometer reads 80mph when going 25mph. Changed speed sensor 2 times from O'reillys. Went to GM and purchased and got same result. Each time a new speed sensor was installed (3 altogether) the speedometer started working perfect and after aprox 2 weeks starts eradict speeds. Surburban is now stuck at 50mph sitting in driveway. If I change the sensor it will automatic go to zero and work perfect.
Is it the part going bad or is something else causing my speedometer problem?
Thks in advance, Ray

4 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

For something like this, it will need to go on a scanner to see if the computer is receiving a correct speed signal from the sensor. If the trans shifts correctly during all of this, the PCM is most likely getting a good signal and theproblem is in the instrument cluster or the signal between the PCM and the cluster

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Tuesday, May 4th, 2010 AT 8:17 AM

JUDDRAY

MEMBER
1 POST

I just don't understand when a new sensor is installed
it works perfect for approx 2 weeks.

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Tuesday, May 4th, 2010 AT 1:30 PM

2CARPRO JACK

MECHANIC
11,533 POSTS

Thats why we need to know what the signal is to the PCM when it is not reading correctly. Odds are good if you reinstalled the sensor that you replaced, it would be ok for a few weeks as well.

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Wednesday, May 5th, 2010 AT 7:52 AM

CH3VYCR4ZY

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3 POSTS

These models had issues with the Instrument Cluster diodes. My 03 had same prob. I replaced the cluster (which is super easy to do) and all gauges returned back to normal. You can go to local parts dealer and you have to fill out a form (to verify mileage) along with your old cluster. Dorman was the parts manufacturer I used, I don't know if there is any others.

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Friday, April 15th, 2011 AT 10:18 PM