Pinpoint Test G: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test G: Incorrect Speedometer Indication
Normal Operation
The PCM calculates vehicle speed from the transmission Output Shaft Speed (OSS) sensor input and from the tire size and axle ratio configuration in the Vehicle Identification (VID) block of the PCM. The PCM provides the Instrument Cluster (IC) with the Vehicle Speed Sensor (VSS) signal over the High Speed Controller Area Network (HS-CAN) communication bus. The IC monitors the VSS input from the PCM and commands the speedometer with a corresponding movement of the pointer.
If the vehicle speed data is missing 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. If the IC does not receive the vehicle speed data 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 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).
Other factors that could potentially affect the accuracy of the speedometer are configurable items such as tire size and axle ratio.
NOTE: If DTC U0100 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
- OSS sensor
- IC
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 label on the LH B-pillar. Refer to Vehicle/Application and ID.
- Select programmable parameters and verify that the vehicle has the correct tire size according to the certification label and the tire size is correctly configured in the PCM.
- Is the tire size correct and is the tire size parameter correctly configured?
Yes
GO to G2.
No
CONFIGURE the tire size. 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.
- Select programmable parameters and verify that the axle ratio is correctly configured in the PCM.
- Is the axle ratio parameter correctly configured?
Yes
GO to G3.
No
CONFIGURE the axle ratio. TEST the system for normal operation.
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G3 RETRIEVE THE RECORDED DTCs FROM BOTH CONTINUOUS AND ON-DEMAND PCM SELF-TESTS
- Check the recorded PCM DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
Yes
REFER to Computers and Control Systems Information.
No
GO to G4.
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G4 RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND IC SELF-TESTS
- Check for recorded IC DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
Yes
For DTC U0100, Go To Pinpoint Test AE. Pinpoint Tests AE: DTC U0100
For DTC U2023, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to 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 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), indicate the different vehicle speeds 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 (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 speedometer begin at 0 km/h (0 mph) and move by approximately 19 km/h (12 mph) for each 10% increment?
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 IC VSS INPUT
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC vehicle speed PID (VSS_IC). Drive the vehicle and monitor the VSS PID at various speeds.
- Does the PID display approximately match the speedometer indication?
Yes
INSTALL a new OSS sensor. TEST the system for normal operation.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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