my 1991 honda accord has an issue with the speedo , it only works sometime for example going approx 80 kms the speedo with randomly bounce all the way up to 140 then as you slow down it goes down to 120 then just drop right off to zero i was told that it may be the "vss" but i changed it with ones from wreckers (meaning tried about three of them) all with the same result i need some advise on what to check next?

 

When the speedometer is not working, try to set the cruise control.

If your cruise control works, then the VSS is working properly and would indicate a problem with the speedometer gauge in the car or the wiring.

 

the cruise does not work , but that brings me to would all of those units i have , have the very same problem as my first vss ? i also did purchase a new one to see as well and same problem does not work until about 80 kms then flys up to 140 kms

 

Check that you didn't accidentally lose the drive link for the VSS. See Pic attachment.

If the drive link is still there, then It could be a wiring problem. I would test the electrical connector that plugs into the speed sensor with a volt meter.

The VSS connector has three wires. One wire is ground (probably black). The other two wires should be tested for voltage. One will have 12V and the other should have 5V when the key is turned to the II position.

When testing the touch one lead of the volt meter to one pin on the VSS connector and the other lead of the volt meter to a known ground (engine block). Use the voltage setting to test for voltage, obviously. Use the continuity or the resistance setting for testing the ground wire. The ground circuit should read closed or zero resistance.

 

this all makes sense and for a while i thought the drive link may not have been in but it is and would not explain why it randomly comes on and goes to the high speed i will test it because anything at this point would be awesome i hat guessing speed too slow or too fast i dunno but those photo radar cameras iam sure would tell me

 

something weird to add on today i was going aprox 100 kms and the speedo spun around right to the bottom then as i slowed down to approx 40 kms it spun around and hit zero wtf ? also to add on my odometer and trip odo. still work but check engine is on and when driving it flashes " S" as well