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Alex, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1161
Experience:  ASE Certified Master Technician, L1 Advanced Level Specialist
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1998 Chevy: 10 4X4..working.I installed a new speed sensor..problem.

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I have a 1998 Chevy S-10 4X4, with a 4.3 engine.

The speedometer quit working.
I installed a new speed sensor, on the side of the transmission. It did not fix the problem.
I had the speedometer head tested, and it's OK.

Where should I look next?

Mike Wilcox [email protected]
Does the vehicle have an automatic or manual transmission?
Customer: replied 6 years ago.
automatic transmission
Ok can you tell me if the sensor you replaced was on the driver's side or passenger side of the transmission? And, was it near the tail housing of the transmission?
Customer: replied 6 years ago.
it was on the driver's side of the transmission near the tail housing
Ok so it seems you did replace the correct speed sensor. Does your truck have switchable 4wd or automatic?
Customer: replied 6 years ago.

switchable 4wd with 3 buttons on the dash

2 hi

4 hi

4 lo

Ok sorry about the confusion earlier. According to my information, you want to replace the speed sensor in this diagram. Does this look like what you replaced?:

Customer: replied 6 years ago.

I'm trying to get my speedometer to work.


I had a new speed sensor installed, it still don't work.


I had a sweep test run on the speedometer head and it's ok.


Does the speedometer go through the computer some how?

What I'm saying is there is more than one speed sensor on the vehicle. There is one for transmission outputs and one for the instrument panel and cruise control. It sounds like you may have had the wrong speed sensor replaced. The system is very simple; the speed sensor sends an AC voltage signal straight to the instrument panel. Therefore, your problem can only be with the instrument panel itself, the speed sensor for the instrument panel and cruise control, or an open or shorted wire between the speed sensor and the instrument panel (least likely).

Edited by Alex M on 2/9/2011 at 3:17 AM EST
Customer: replied 6 years ago.

Setting in the drivers set, the sensor on the left side was replaced.


You're saying there is a second sensor on the right side of the transmission for the instrument panel. So if I replace it, the speedometer should work.


The S-10 does not have cruise control, if that matters.





Not necessarily. You may want to verify the integrity of the wiring from the sensor to the instrument panel. If you have access to an ohmmeter, with the key off, you can connect one lead to the speed sensor wiring connector pin and the other to the corresponding pin on the instrument panel wiring connector. The wires will be the same color at both connectors. If the meter reads OL the wire is open.
Customer: replied 6 years ago.

This is the last question.


One person told me that the speedometer might so through the computer,

and that I may have to replace the computer.


Does the speedometer go through the computer? Please reply!!!!


I will check out the wiring with an ohmmeter, tomorrow.



Mike Wilcox

West Virginia

I'm sorry I gave you some mis-information due to false information I was given by all data. The VCM (engine computer) does send the speed sensor signal to the instrument panel. So that would make the VCM a possible culprit. What you need to do is check for continuity with an ohmmeter on the dark green wire from the VCM to the instrument panel. Also check the purple/white and light green/black wires from the speed sensor to the VCM. The VCM is on the right side of the engine compartment:


If you have good continuity on all of these wires, and you know the instrument panel is good, then the VCM is at fault.

Before you do any of this, try disconnecting the wiring connector from the stereo and see if the speedometer then works. If it does, the stereo needs to be replaced. This sounds odd but I found this information in the archives for a 98 s-10.
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