ECU, Wiring, Sensors
By gtstwincam
#179833 I have a 1995 civic vx.

The speedometer always works during the first 5-10 minutes of driving, however when the engine warms up, the speedometer begins read incorrectly..

For example... Cruising at 65mph when engine is cold- all is normal.. 5-10 minutes later, speedometer will begin to drop to 40mph and stay within that range..

The guage will no longer read correctly until the next morning- again for about the first ten minutes of driving..

Once in a blue moon, the check engine light code 17 would come on after slowing down from high speed driving

What ive replaced:

3 clusters , new speed sensor, replaced speed sensor harness twice, bypassed vss wires in the harness and ran new wires directly from vss to speedometer cluster- still problem exists.

I reinstalled the vss back to the orig harness and did continuity tests and dc voltage tests..

With multimeter. I connected one end to the yellow/blue wire of vss connector and the other end to the black/yellow wire of speedometer harness.. I get full continuity.. BUT i am also getting continuity on all the remaining pins of the sppedometer harness too! (is this normal?)

i then checked continuity from the yellow/white wire of the vss harness and the yellow/blue wire of the speedometer harness and get full continuity- i checked all the other pins on the speedometer harness and get no readings...

I then did a dc voltage test...

With ign on and mutimeter on dc10, speedometer harness connected, i grounded the multimeter and the positive end connected to the yellow/white wire of the vss plug, i get a voltage reading of about 7v..

I pulled the vss assembly out of the transmission and inspected the gear teeth of the vss housing and it looks good

i inspected the plastic gear in the transmission that is visible through the hole where the Vss mounts and i didnt feel any missing teeth..

I feel drag on the vss when i turn it, not much drag on the gear in the trans..