HOW TO REPAIR SPEEDOMETER NOT WORKING ON 2002 CHEVY BLAZER

Z71guy

• 154 Answers
• Posted on Oct 05, 2010

SOURCE: speedometer stopped working

Pretty common problem with these. Here's a guide to learn how to fix GM instrument clusters yourself, I used it to fix mine and it worked great.How to guide for Trailblazer instrument cluster repair

Jeffrey Turcotte

• 8991 Answers
• Posted on Mar 01, 2011

SOURCE: 2002 chevy s10 blazer 4x4.

Hi, the speed sensor is powered by the PCM via the 10 amp fuse labeled IGN E under the hood. I don't believe your problem is the fuse, as the truck would not likely run if that fuse was bad. The more likely problem is with the speed sensor itself. Sorry I do not have a test procedure for this sensor, so I can't guarantee a new sensor will solve the problem. What you can do is while the truck is jacked up with the drive wheels off the ground (use 2WD), use a voltmeter to back-probe each terminal of the sensor with a voltmeter (put the other probe to chassis ground), and check the voltage with the car running in park versus running in gear. One of the terminals will have a reference voltage and the other the signal. If the signal changes with speed, the sensor is probably working, and the problem would then more likely be the instrument cluster. Let's hope it isn't the cluster, because they are more expensive. A new sensor is just $22 at Autozone. I have pasted instructions below for replacing the sensor. Please let me know if you have questions, and thanks for using FixYa.

Removal & Installation

1. Raise the vehicle.
2. Remove the bolts (1, 3) securing the front transaxle brace (2) to the transaxle and right cylinder head.
3. Remove the electrical connector at the vehicle speed sensor.
4. Remove the retaining bolt (1) and the sensor (2). Twisting the sensor while pulling outward will aid in removal.
   

Fig. Removing front transaxle brace (2) after removing bolts (1 and 3)

Fig. Removing vehicle speed sensor (2)

To install:


CAUTION Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

1. Install the vehicle speed sensor and the retaining bolt. Install a new O-ring seal on sensor if necessary. Tighten the bolt to 10 Nm (89 inch lbs.).
2. Install the electrical connector at the sensor. Install the bolts securing the front transaxle brace to the transaxle and right cylinder head.
3. Lower the vehicle.

SOURCE: How do you repair the

This sounds like the sending unit in the tank change it out it should fix the problem.