Vehicle Speed Sensor (VSS)

Unplug 6-pin connector at amplifier. Measure resistance between Pin No. 2 and Pin No. 3 at 6-pin connector.
Resistance should be 200-300 ohms. Resistance near zero ohms indicates a shorted coil; high resistance indicates an open coil in sensor or open wire in harness.
If test was performed at amplifier connector, repeat test at sensor terminals. Replace sensor if resistance is not 200-300 ohms. Repair wiring harness if sensor resistance is okay.
If resistance is 200-300 ohms and speedometer operates properly without needle waver, sensor is probably good (possible intermittent condition). If necessary, substitute a known good sensor to check operation.