420A Speed Sensor

[poonman]

Ok well i woke up theis morning drove to get gas, got back in the car and bam the speedo isnt working, i located the sensor and cleaned the terminals but still no luck.

If the sensor went bad wouldnt I get a CEL, because i dont have one. so i have no clue wut to look for now.

 

[awamsley]

You wouldn't get a CEL with a faulty speed sensor. Just to make sure you checked the right one, it sits on top of the transmission. It's easist to service if you take out the battery and tray.

 

[VelocitàPaola]

Also, remove the VSS and make sure the gear on the end hasn't fallen into the transmission. As a last resort, you can always swap the odometer/speedometer module in the gauge cluster to check if that's the problem.

 

[RSTeclipse97]

the speed sensor gear in my trans has been broke for two years now and i have never gottin a cel

 

[poonman]

ok i got a new update, i started my car this morning and now the speedo is jumping all over the place even when im at a dead stop . im going to pull it out and change it anyways i just hope its the problem.

 

[kergilman]

ok i got a new update, i started my car this morning and now the speedo is jumping all over the place even when im at a dead stop . im going to pull it out and change it anyways i just hope its the problem.

Sounds like the VSS is barely making gear contact and giving you spuratic results (VSS uses voltage pulses instead of a variable voltage for the conversion from mechanical to electrical readings)

 

[hellarough]

You wouldn't get a CEL with a faulty speed sensor. Just to make sure you checked the right one, it sits on top of the transmission. It's easist to service if you take out the battery and tray.

Really? I remember that in my auto class in high school we had a trans-am that put up an error code on OBD because of a faulty VSS. Wouldn't that mean there would also be a CEL?

 

[Locke]

The ECU in a MTX DSM has nothing to compare VSS information to in order to determine it's function. The TA was likely an automatic, which would have two speed sensors and other information from the TCU.