Pinpoint Test G: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test G: Incorrect Speedometer Indication
Normal Operation
The Instrument Panel Cluster (IPC) receives the vehicle speed signal from the PCM over the High Speed Controller Area Network (HS-CAN). The PCM receives the vehicle speed signal input from the transmission Output Shaft Speed (OSS) sensor. The IPC monitors the vehicle speed signal input from the PCM and commands the speedometer with a corresponding movement of the pointer.
The IPC provides a tolerance which allows the gauge to display between 3% lower and 7% higher than the actual vehicle speed. This means that with an actual vehicle speed of 96.6 km/h (60 mph), the speedometer may indicate between 93.7-103.3 km/h (58.2-64.1 mph). Factors that could potentially affect the speedometer accuracy are incorrect tire size configuration and axle ratio configuration.
If the IPC receives invalid vehicle speed data from the PCM for 5 seconds or less, the IPC defaults the speedometer to the last setting, based upon the last known good vehicle speed message. If the IPC does not receive the vehicle speed data from the PCM for more than 5 seconds, the IPC sets DTC U0100:00 in continuous memory and defaults the speedometer to 0 km/h (0 mph). If the vehicle speed data received is deemed invalid by the IPC, the IPC sets DTC U0401:00 and defaults the speedometer to 0 km/h (0 mph).
NOTE: If DTC U0100:00 sets in the IPC, other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- Tire size configuration
- Axle ratio configuration
- PCM concern
- IPC
PINPOINT TEST G: INCORRECT SPEEDOMETER INDICATION
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G1 CHECK THE TIRE SIZE CONFIGURATION
- Enter the following diagnostic mode on the scan tool: Module Programming.
- NOTE: The correct tire size can be found on the Vehicle Certification (VC) label on the LH B-pillar. Refer to Identification Codes Application and ID.
- Verify the size of the tires installed on the vehicle matches the VC label.
- Verify the tire size configuration matches the VC label.
- Is the tire size correct and is tire size correctly configured?
Yes
GO to G2.
No
INSTALL the correct size tires or CONFIGURE the correct tire size as required. TEST the system for normal operation.
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G2 CHECK THE AXLE RATIO CONFIGURATION
- Enter the following diagnostic mode on the scan tool: Module Programming.
- NOTE: The correct axle ratio can be found on the Vehicle Certification (VC) label on the LH B-pillar. Refer to Identification Codes Application and ID.
- Verify the axle ratio configuration matches the VC label.
- Is the axle ratio correctly configured?
Yes
GO to G3.
No
CONFIGURE the correct axle ratio. TEST the system for normal operation.
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G3 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST
- Check the recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- Are any DTCs recorded?
Yes
REFER to Computers and Control Systems. TEST the system for normal operation.
No
GO to G4.
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G4 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded IPC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC U0100:00, GO to Pinpoint Test AT Pinpoint Tests AT: DTC U0100:00. For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to G5.
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G5 CARRY OUT THE SPEEDOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Select the IPC speedometer (SPDOMETER) active command. Command the speedometer in 10% increments while monitoring the speedometer. The speed indicated should increase in increments of approximately 19 km/h (12 mph) for each 10% change.
- Does the speed indicated increase according to the above specifications?
Yes
GO to G6.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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G6 CHECK THE PCM VSS PIDs
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select the PCM vehicle speed (VSS) PID and monitor the PID while driving the vehicle at 32 km/h (20 mph), 64 km/h (40 mph) and 97 km/h (60 mph).
- Does the speedometer indicate between 31-34 km/h (19-21 mph), 63-69 km/h (39-43 mph) and 93-103 km/h (58-64 mph) at the 3 PCM PID values?
Yes
GO to G7.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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G7 OBSERVE THE SPEEDOMETER OPERATION
- Ignition ON.
- Observe the speedometer while driving the vehicle at various speeds and stopping frequently.
- Does the speedometer begin at 0 km/h (0 mph) and fully return to the 0 km/h (0 mph) position when the vehicle is stopped?
Yes
The speedometer is operating correctly at this time.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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