G: Speedometer/Odometer Reads Inaccurately-SHO only

G1 Check Speedometer
- Road test vehicle

Is speedometer operating?

Yes
Go to G2
No
Go to G5

G2 Check The Odometer Reading
- drive vehicle over a known distance

Is odometer reading inaccurately?

Yes
Go to G3
No
Go to G4

G3 Check Speedometer Accuracy
- Drive vehicle at a steady speed over a 0 km (16 mile) distance and record the total distance travelled.

Does speedometer meet speedometer calibration tolerance specification?

Yes
System OK
No
REPLACE speedometer assembly

G4 Check SARC Vehicle Speed PID
- connect Rotunda New Generation Star Tester or equivalent to data link connector C229 beneath instrument cluster.
- Access SARC PID: VSS_SRC. Refer to Suspension Control for procedure and entre PID list.
- Drive vehicle.
- Observe vehicle speed via PID VS_SRC

Does vehicle speed indicated in PID: VSS_SRC reflect approximate vehicle speed?

Yes
Go to G5
No
SERVICE Circuit 679 (GY/BK). Go to Antilock Brakes / Traction Control Systems.

G5 Check Circuit 679 (GY/BK) For Open Circuit
- Using an ohmmeter connect one lead to Circuit 679 (GY/BK) at anti-lock brake control module connector Pin C1057 and the other lead to instrument cluster Pin C251, Circuit 679 (GY/BK).
- Measure resistance.

Is resistance less than 5 ohms?

Yes
GO to G6.
No
SERVICE Circuit 679 (GY/BK) for open circuit. RESTORE vehicle. RETEST system.

G6 Check Circuit 398 (BK/Y) Ground
- Connect ohmmeter to instrument cluster connector Pin C250 , Circuit 398 (BK/Y).
- Measure resistance to known good ground.

Is resistance 5 ohms or less?

Yes
GO to G7.
No
SERVICE Circuit 398 (BK/Y) for open circuit. RESTORE vehicle. RETEST system.

G7 Check Clip To Cluster Circuit Connector
- Disconnect instrument cluster connectors C250 and C251
- Using an ohmmeter, measure resistance of speedometer indicator terminals to printed circuit where they seat.

Is resistance 1 ohm or less at each indicator terminal?

Yes
GO to G8.
No
REPLACE contact clips. RESTORE vehicle. RETEST system.

G8 Check Printed Circuit
- Reconnect cluster connectors.
- Using an ohmmeter, measure resistance from speedometer contact clips to instrument cluster connector according to chart.

Pin/Clip Function

C251 Power Input (RUN)

C250 Ground

C251 Vehicle Speed Input Signal

Is resistance less than 1 ohm?

Yes
REPLACE speedometer assembly. RESTORE vehicle. RETEST system.
No
REPLACE instrument cluster printed circuit. RESTORE vehicle. RETEST system.