Continuous Zero Mph Speedometer Reading
- While test driving vehicle, enter diagnostics and select ECM data ED12. Note indicated vehicle speed. Select BCM data input BD60 and note indicated vehicle speed.
- If ECM data ED12 and BCM data BD60 are the same value, but not zero, replace the IPC. If ECM data ED12 reads zero and BCM data input BD60 reads zero, proceed to step 3).
- Connect a voltmeter from terminal 3C10 (Yellow wire) to terminal 3C1 (Purple wire). Put voltmeter in AC 20-volt scale and raise front wheels with vehicle in neutral and engine off. Turn front wheels by hand.
- If voltage is not above zero (depending on wheel speed), check and repair Yellow and Purple wires for opens.
- If wires are good, replace Vehicle Speed Sensor (VSS). If there is voltage, replace BCM.