Speedo jumps while stopped
Thread Starter
2nd Gear
Joined: Apr 2006
Posts: 2
Likes: 0
Speedo jumps while stopped
Vette owners,
Re: 1996 Corvette Grand Sport
I need some advise on this matter before I go in for repair. While fully stopped, my speedometer randomly jumps around between 0 and 7 MPH. It started happening after I had the car dyno tuned. Has anyone else experienced this, or can anyone offer a possible source of this problem?
Thanks,
John
Re: 1996 Corvette Grand Sport
I need some advise on this matter before I go in for repair. While fully stopped, my speedometer randomly jumps around between 0 and 7 MPH. It started happening after I had the car dyno tuned. Has anyone else experienced this, or can anyone offer a possible source of this problem?
Thanks,
John
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
This is most likely caused by RFI (radio frequency interference) on your vss signal wiring. This may be difficult to correct, short of shielding the wires, or moving the harness around.
The vss wiring runs from the transmission inside the driver's side rocker panel, and is routed somehow to the ecm/pcm. First look for loose connections, loose spark plug wires, etc. Then check the routing of the vss harness where it is close to other voltage sources, like the battery cables.
During your dyno tuning, maybe they pulled or moved a plug wire for an inductive rpm pick-up. Check for loose plug wires first
After re-locating my battery, I experienced similar issues, mostly while idling with my foot on the brake, when some alt. load is present. Its annoying but I can live with it.
You may see some idle instability as the idle control mode changes from PID control to park position/throttle follower mode when some vehicle speed is present.
The vss wiring runs from the transmission inside the driver's side rocker panel, and is routed somehow to the ecm/pcm. First look for loose connections, loose spark plug wires, etc. Then check the routing of the vss harness where it is close to other voltage sources, like the battery cables.
During your dyno tuning, maybe they pulled or moved a plug wire for an inductive rpm pick-up. Check for loose plug wires first
After re-locating my battery, I experienced similar issues, mostly while idling with my foot on the brake, when some alt. load is present. Its annoying but I can live with it.
You may see some idle instability as the idle control mode changes from PID control to park position/throttle follower mode when some vehicle speed is present.
