Pinpoint Test H: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test H: 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) communication bus. The vehicle speed data originates with the wheel speed sensors on 4-channel ABS and from the wheel speed sensors and rear axle sensor on the 3-channel ABS. The ABS module provides the rear axle speed data to the PCM over the HS-CAN communication bus. The IPC monitors the vehicle speed 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 H: INCORRECT SPEEDOMETER INDICATION
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H1 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 label on the LH B-pillar. Refer to Identification Codes Application and ID.
- Verify the vehicle has the correct tire size according to the certification label and the tire size is correctly configured.
- Is the tire size correct and is tire size correctly configured?
Yes
GO to H2.
No
CONFIGURE the correct tire size. TEST the system for normal operation.
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H2 CHECK THE AXLE RATIO CONFIGURATION
- Enter the following diagnostic mode on the scan tool: Module Programming.
- Verify the axle ratio is correctly configured.
- Is the axle ratio correctly configured?
Yes
GO to H3.
No
CONFIGURE the correct axle ratio. TEST the system for normal operation.
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H3 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 H4.
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H4 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 BA. For all other DTCs, REFER to DTC Charts. Pinpoint Tests BA: DTC U0100:00
No
GO to H5.
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H5 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 H6.
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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H6 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 16 km/h (10 mph) for each 10% change.
- Does the speed indicated increase by 16 km/h (10 mph) for each 10% increment?
Yes
GO to H7.
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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H7 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
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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