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98 cavalier speedometer issues

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Dwprice

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I have a 98 cavalier automatic. The speedometer over a few month period stopped working and the odometer isn't working either. I have replaced the vss and nothing changed. I then replaced the speedometer with one from a junk yard and nothing changed( had issues with the anti theft, but was able to start the car and unplug the old and plug in the new and it did not work). I have inspected the wiring harness to the best of my ability and can find no visual issues with the harness. Can someone help? How can I test the wires to see if there is a short in them. The connector going to the vss has a purple and a yellow wire. Is there an easy way to trouble shoot them. The purple wire has continuity if I hold a multi meter to it and the frame of the car. Is that correct. I am at my wits end with this issue. The car shifts fine, I also disconnected the sensor and drove it and no codes or change in the vehicles condition. Any info or instructions will be helpful.
 
Trying to understand the input system for the speedometer. there are 2 wires yellow (high) purple (low) can someone explain this to me. I hooked a multimeter to the connector. The purple is showing that it is grounded the yellow is not. Is this correct? Could this be my problem?
 
Also, is there possibly a different sensor that controls the speedometer?
 
The sensor is not the issue at this point. The issue is how to shoot and trace down the wires. Every component in the system minus the computer and wires have been replaced. I need to know what response I should get from a multi meter when shooting the wires and the wires only. This car is very low miles and the harness's look brand new. But, the speedometer and the vss have been replaced and I am having the same issue. (speedometer and odometer are not working, but the vehicle shifts and drives w/o issue.) From what I have read if the vss is bad the car will shift horribly or not at all.
 
did you replace the vss with a new vss or a used vss ?
how do you know the used speedometer isnt broken?
Based on the explanation of how it works neither wire should show a complete circuit when a probe is inserted into either one and the other probe is grounded.
 
vss is new, as for the speedometer i don't know. I have no way to test it. Is there a way to test a speedometer? The purple wire (low input) is grounded for some reason. The yellow is not. So that could be my problem.
 
i would start tracing the wires for a short
 
Update, I was able to track down the input wires for the vss going into the pcm and tested them for continuity. Good there. I also tracked down the wire from the pcm to the speedometer. No issues there either. Is there anything else in the loop that I could be missing. Just to test I disconnected the vss connector and drove the care down the road so I could see how it acted. Obviously the car wouldn't shift gears. My thoughts would be that the car is getting signal to the pcm from the vss. What are your thoughts.
 
when you say you tracked down the wire from the pcm to the speedometer you were able to determine that a signal was going to the speedometer?
 
No, I just found out which wires were going into the pcm from the vss and which wires were going from the pcm to the speedometer. I checked to make sure that there was not a short in the wires and to make absolutely sure I wired in a new vss connector and ran new wires from the vss to the pcm and then ran a new wire from the pcm to the speedometer and no change. With that being said when I disconnect the vss connector the vehicle does not change gears so I know the signal is getting to the pcm. Could it be possible that the pcm is not sending a the signal to the speedometer? With that being said would the vehicle throw a code if this was the case. There is no check engine light on and never has been. I guess at this point it is obvious that the signal is not getting to the speedo, but why? VSS_CONNECTOR-WIRES-PCM-SPEEDO have all been replaced and 0 change. Is there another sensor that controls the speedo on this car. I have searched and searched but can't find any hard evidence.
 
either the signal is not going to the speedometer or the replacement speedometer is defective
 
How would you test the signal going to the speedometer? The dash is still open so I can put the car on jack stands and test the wire from the connector that goes into the speedo. What should it read?
 
Also, I swapped the cluster motors from the water temp to the speedo to make sure that the motor was not the proplem. The water temp guage worked and the speedo still was inop. So I know it's not the speedo motor.
 
Update, I purchased an obd2 scanner with live data and took the car for a drive. I am getting a reading from the vss sensor. So i'm guessing the speedo I purchased was bad??
 
Do you know of any instrument cluster repair companies. I have done a google search and can't seem to find any that work on my year model. 99 and newer is all I have found.
 
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