F: Speedometer/Odometer Reads Inaccurately
Pinpoint Test F - Speedometer/Odometer Reads InaccuratelyF1 - Check Speedometer
- Road test vehicle.
Is speedometer operating?
YES GO to F2.
NO GO to F5.
F2 - Check Odometer Accuracy
- Drive vehicle over a known distance.
Is odometer reading accurately?
YES GO to F3.
NO GO to F4.
F3 - Check Speedometer Accuracy
- Drive vehicle at a steady speed over a known distance and record the time it took to travel that distance.
Does speedometer meet Speedometer Calibration Tolerance Specifications?
YES System OK.
NO REPLACE speedometer assembly.
F4 - Check For Correct Speed Gears
- Check for correct driven gear on speed sensor.
Is driven gear present in transmission and driven gear as shown on chart?
YES GO to F5.
NO INSTALL correct drive and driven gear. RETEST system.
F5 - Check Speed Signal Between Circuits 679 (GY/BK) And 676 (PK/O)
- Raise drive wheels off the ground.
- Disconnect vehicle speed sensor connector.
- Connect an ac voltmeter between the two output pins on the automatic transmission mounted vehicle speed sensor.
- Operate vehicle.
Is voltage between 1.3-6.1 volts ac?
YES GO to F8.
NO GO to F6.
F6 - Check Driven Gear
- Disconnect vehicle speed sensor from automatic transmission.
- Verify presence of speedometer gear with all teeth in good condition and presence of retainer clip.
Are driven gear teeth OK and is clip present?
YES GO to F7.
NO REPLACE with proper speedometer gear and clip. RESTORE vehicle. RETEST system.
F7 - Check Drive Gear
- Verify presence of speedometer drive gear on output shaft.
Is drive gear present?
YES REPLACE vehicle speed sensor. RESTORE vehicle. RETEST system.
NO SERVICE transmission as necessary. RESTORE vehicle. RETEST system.
F8 - Check Circuit 679 (GY/BK) For Short To Ground
- Turn ignition switch to the OFF position.
- Remove instrument duster as outlined.
- Using an ohmmeter connected to a known good ground, connect second lead to instrument cluster connector pin C1-16, circuit 679 (GY/BK).
- Measure resistance.
Is resistance 5 ohms or less?
YES SERVICE circuit 679 (GY/BK) for short. RESTORE system. RETEST system.
NO LEAVE ohmmeter connected to circuit 679 (GY/BK). GO to F9.
F9 - Check Circuit 679 (GY/BK) For Open Circuit
- Using a jumper wire connected to a known good ground connect other end to circuit 679 (GY/BK) at the vehicle speed sensor connector.
- Measure resistance.
Is resistance 5 ohms or less?
YES GO to F10.
NO SERVICE circuit 679 GY/BK) for an open. RESTORE system. RETEST system.
F10 - Check Vehicle Speed Sensor Ground Circuit
- Disconnect vehicle speed sensor connector.
- Using an ohmmeter connected to a known good ground, connect second lead to circuit 676 (PK/O) at vehicle speed connector.
Is resistance 5 ohms or less?
YES GO to F11.
NO SERVICE circuit 679 (GY/BK) for an open. RESTORE vehicle. RETEST system.
F11 - Check Vehicle Speed Sensor Resistance
- Connect an ohmmeter between vehicle speed sensor terminals.
Is resistance 175-400 ohms?
YES GO to F12.
NO REPLACE vehicle speed sensor. RESTORE vehicle. RETEST system.
F12 - Check Circuit 676 (PK/O) For Open Circuit
- Disconnect ohmmeter from circuit 679 (GY/BK), connect ohmmeter to circuit 676 (PK/O), connector pin C1-14.
- Measure resistance to known good ground.
Is resistance 5 ohms or less?
YES GO to F13.
NO GSERVICE circuit 676 (PK/O) for an open. RESTORE system. RETEST system.
F13 - Check Clip To Cluster Circuit Connector
- Disconnect instrument cluster connectors C1 and C2.
- Using an ohmmeter, check speedometer for continuity from contact clips to flex circuit.
Is there continuity at all clips?
YES GO to F14.
NO REPLACE contact clips. RESTORE vehicle. RETEST system.
F14 - Check Printed Circuit
- Reconnect cluster connectors.
- Using an ohmmeter, check for continuity from speedometer contact clips to instrument cluster connector per chart.
Pin Circuit Function
C1-12 1053 (LB/PK) Power Input
C2-3 640 (R/Y) Power Input
C1-14 676 (PK/O) Ground
C1-16 679 (GY/BK) Vehicle Speed Input (Signal)
Is there continuity at all circuits?
YES REPLACE speedometer assembly. RESTORE vehicle. RETEST system.
NO REPLACE instrument cluster flex circuit. RESTORE vehicle. RETEST system.