Pinpoint Test G: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test G: Incorrect Speedometer Indication
Normal Operation
The Instrument Cluster (IC) receives the vehicle speed signal from the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The PCM generates or receives the vehicle speed data from different sources depending on which transmission and Four-Wheel Drive (4WD) system/2-Wheel Drive (2WD) combination.
Vehicles With 4R70E/4R75E Transmissions and Electronic Shift-On-The-Fly (ESOF) 4WD or 2WD
The vehicle speed data originates with the Output Shaft Speed (OSS) sensor. The OSS sensor sends the output shaft speed data to the Transmission Control Module (TCM). The TCM provides the output shaft speed data to the PCM over the HS-CAN bus. The PCM uses the messaged output shaft speed data along with the tire size and axle ratio configuration stored in the Vehicle Identification (VID) block to generate the vehicle speed data sent to the IC.
Vehicles With 4R70E/4R75E or 6R80 Transmissions and Mechanical Shift-On-The-Fly (MSOF) 4WD
The vehicle speed data is calculated in the PCM using 2 inputs sent from the ABS module over the HS-CAN bus. The first input is an uncompensated vehicle speed message and the second input is a compensation factor message.
Vehicles With 6R80 Transmission and ESOF 4WD or 2WD
The vehicle speed data originates with the OSS sensor. The OSS sensor sends the data to the TCM. The TCM provides the output shaft speed data to the PCM over the HS-CAN bus. The PCM uses the messaged output shaft speed data along with the tire size and axle ratio configuration stored in the Vehicle Identification (VID) block to generate the vehicle speed data sent to the IC. In the event the OSS signal is not present to the PCM or the vehicle speed message is missing from the TCM, the PCM calculates the vehicle speed input from the ABS vehicle speed HS-CAN message.
The IC provides a tolerance which biases the speed indication and allows the gauge to display between 3% lower and 7% higher than the actual vehicle speed. This means that with a 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 speedometer accuracy are incorrect tire size configuration and axle ratio configuration.
If the vehicle speed data is missing or invalid for 5 seconds or less or if the IC receives invalid vehicle speed data for 5 seconds or less, the IC defaults the speedometer to the last setting, based upon the last known good vehicle speed message received.
NOTE: If DTC U0100 is set in the IC, other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
If the IC does not receive the vehicle speed data message from the PCM for more than 5 seconds, the IC sets DTC U0100 in continuous memory and defaults the speedometer to 0 km/h (0 mph).
If the vehicle speed data is deemed invalid by the IC for more than 5 seconds, the IC sets DTC U2197 and defaults the speedometer to 0 km/h (0 mph).
This pinpoint test is intended to diagnose the following:
- Tire size configuration
- Axle ratio configuration
- PCM concern
- ABS module
- IC
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: Module Programming.
- NOTE: The correct tire size can be found on the vehicle certification label on the LH B-pillar. Refer to Vehicle Identification Codes.
- 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 is correctly configured in the PCM.
- Is the tire size correct and are the 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 DTCs recorded?
Yes
REFER to Computers and Control Systems.
No
GO to G3.
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G3 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 U0100, GO to Pinpoint Test AP. Pinpoint Tests AP: DTC U0100
For all other DTCs, REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
If equipped with a 4R70E/4R75E or 6R80 transmission and MSOF 4WD, GO to G4.
If equipped with a 4R70E/4R75E transmission with ESOF or 2WD or 6R80 transmission with ESOF 4WD or 2WD, GO to G5.
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G4 RETRIEVE THE RECORDED DTCs FROM THE ABS MODULE SELF-TEST
- Check for recorded ABS DTCs from the self-test.
- Are any DTCs recorded?
Yes
REFER to Antilock Brakes / Traction Control Systems.
No
GO to G5.
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G5 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 G6.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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G6 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 (SPD_IND) active command. and scroll in 10% increments.
- Does the speedometer start at 0 km/h (0 mph) and increase by 19.3 km/h (12 mph) for each 10% increase commanded?
Yes
GO to G7.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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G7 CHECK THE PCM VEHICLE SPEED PIDs
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Select the PCM vehicle speed PID (VSS) 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 IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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