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 Sensor (VSS) signal from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The PCM receives the VSS input from the Output Shaft Speed (OSS). The IPC monitors the VSS input from the PCM and commands the speedometer with a corresponding movement of the pointer.
Factors that could potentially affect the accuracy of the speedometer are configurable items such as tire size.
If the vehicle speed data is missing for 5 seconds or less or if the IPC receives invalid vehicle speed data 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 for 5 seconds or longer, the IPC sets DTC U0401:00 and defaults the speedometer to 0 km/h (0 mph).
NOTE: If DTC U0100:00 is set in the IPC, other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- PCM
- IPC
NOTE: The speedometer should not be ruled at fault if the speedometer does not match the set speed display. The speedometer can vary from approximately 1% lower to 3% higher than the set speed display depending on vehicle speed. This is due to a tolerance built into the speedometer software and does not indicate a failure of the speedometer.
PINPOINT TEST G: INCORRECT SPEEDOMETER INDICATION
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G1 CHECK THE TIRE SIZE AND AXLE RATIO CONFIGURATION
- Enter the following diagnostic mode on the scan tool: PCM Module Programming.
- NOTE: The correct tire size can be found on the vehicle certification label on the LH B-pillar. Refer to Vehicle/Application and ID.
- From the programmable parameters menu, verify that the vehicle has the correct tire size according to the certification label and the tire size and axle ratio are correctly configured in the PCM.
- Is the tire size correct and are tire size and axle ratio parameters correctly configured?
Yes
GO to G2.
No
CONFIGURE the PCM for the correct tire size. TEST the system for normal operation.
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G2 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO SELF-TEST
- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
- Are any PCM DTCs recorded?
Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems Information.
No
GO to G3.
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G3 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded DTCs from the IPC self-test.
- Are any DTCs recorded?
Yes
For DTC U0100:00, Go To Pinpoint Test AO. Pinpoint Tests AO: DTC U0100:00
For DTC U0401:00, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to Computers and Control Systems Information and Body Control Systems for a list of all DTCs.
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to G4.
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G4 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
GO to G5.
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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G5 CARRY OUT THE IPC 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 and command the speedometer in increments of approximately 10%. Observe the speedometer. The speedometer starts at 0 km/h (0 mph) and moves approximately 22.5 km/h (14 mph) for each 10% increment.
- Does the speedometer begin at 0 km/h (0 mph) and move by approximately 22.5 km/h (14 mph) for each 10% increment?
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
INSTALL a new PCM. TEST the system for normal operation.
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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