Pinpoint Test H: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test H: Incorrect Speedometer Indication
Normal Operation
The PCM receives the vehicle speed data from the Output Shaft Speed (OSS). The PCM provides the Instrument Cluster (IC) with the vehicle speed signal over the High Speed Controller Area Network (HS-CAN) communication bus.
The vehicle speed is calculated in the PCM from the OSS sensor input and the tire size information programmed into the Vehicle Identification (VID) block at the end of the line production. The IC monitors the vehicle speed input from the PCM and commands the speedometer with a corresponding movement of the pointer.
The IC provides a tolerance which biases the speedometer indication and displays between 3% lower and 7% higher than the actual vehicle speed. This means with an actual vehicle speed of 96.6 km/h (60 mph), the speedometer may indicate between 93.7-103.3 km/h (58.2-64.2 mph). Other factors that could potentially affect the accuracy of the speedometer are configurable items such as tire size and axle ratio configuration.
If the vehicle speed data is missing or invalid for 5 seconds or less, the IC defaults the speedometer to the last setting, based upon the last known good vehicle speed message. If the IC does not receive the vehicle speed data from the PCM for more than 5 seconds, the IC sets DTC U0101 in continuous memory and defaults the speedometer to 0 km/h (0 mph). If the vehicle speed data received is deemed invalid by the IC for 5 seconds or longer, the IC sets DTC U2023 and defaults the speedometer to 0 km/h (0 mph).
NOTE: If DTC U0101 is set in the IC, 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
- IC
PINPOINT TEST H: INCORRECT SPEEDOMETER INDICATION
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H1 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 H2.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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H2 CHECK THE VEHICLE 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 Identification Codes 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 the size and axle ratio parameters correctly configured?
Yes
GO to H3.
No
CONFIGURE the PCM for the correct tire size and axle ratio. TEST the system for normal operation.
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H3 RETRIEVE THE RECORDED DTCs FROM KOEO PCM 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 Information.
No
GO to H4.
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H4 RETRIEVE THE RECORDED DTCs FROM THE IC SELF-TEST
- Check for recorded IC DTCs from the self-test.
- Are any DTCs recorded?
Yes
For DTC U0101, GO to Pinpoint Test AM. Pinpoint Tests AM: DTC U0101
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to H5.
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H5 CARRY OUT THE SPEEDOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC 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 begin at 0 km/h (0 mph) and increase by 19 km/h (12 mph) for each 10% increment?
Yes
GO to H6.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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H6 CHECK THE PCM VSS INPUT
NOTE: An assistant may be required to monitor the scan tool display and the speedometer indication during the test step.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select the PCM vehicle speed PID (VSS_IC). Drive the vehicle and monitor the VSS PID 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 IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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