Pinpoint Test H: Incorrect Speedometer Indication
Instrumentation and Warning Chimes
Pinpoint Test H: Incorrect Speedometer Indication
Normal Operation
The ABS module monitors the wheel speed sensors and sends wheel speed data to the PCM over the High Speed Controller Area Network (HS-CAN) communication bus. The PCM generates a master vehicle speed message based on the ABS wheel speed data and sends it to the Instrument Cluster (IC) over the HS-CAN (High Speed Controller Area Network) communication bus. The IC (Instrument Cluster) monitors the vehicle speed input and commands the speedometer with a corresponding movement of the pointer.
The IC (Instrument Cluster) allows the gauge to display between 0% and 7% higher than the vehicle speed input it is receiving. This means that with an actual vehicle speed of 96.6 km/h (60 mph), the speedometer may indicate between 96.6-103.3 km/h (60-64.2 mph). The speedometer would not indicate lower than the actual vehicle speed. Other factors that could potentially affect the speedometer accuracy are incorrect tire size.
If the vehicle speed data is missing or invalid for 5 seconds or less, the IC (Instrument Cluster) defaults the speedometer to the last setting, based upon the last known good vehicle speed message. If the IC (Instrument Cluster) does not receive the vehicle speed data from the PCM for more than 5 seconds, the IC (Instrument Cluster) 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 (Instrument Cluster) for 5 seconds or longer, the IC (Instrument Cluster) sets DTC U2197 and defaults the speedometer to 0 km/h (0 mph).
NOTE: If DTC U0100 is set in the IC (Instrument Cluster), other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- Tire size
- PCM concern
- ABS concern
- IC (Instrument Cluster)
PINPOINT TEST H : INCORRECT SPEEDOMETER INDICATION
H1 OBSERVE THE SPEEDOMETER OPERATION
- 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 (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
H2 CHECK THE VEHICLE TIRE SIZE
- Using the certification label located in the LH front door area, verify that the vehicle is equipped with the correct tire size.
Does the tire size match the certification label?
Yes
GO to H3.
No
INFORM the customer that tire size affects the accuracy of the speedometer.
H3 RETRIEVE THE RECORDED DTCs FROM KOEO (Key ON Engine OFF) PCM SELF-TEST
- Check the recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
Are any DTCs recorded?
Yes
REFER to the Computers and Control Systems Information.
No
GO to H4.
H4 RETRIEVE THE RECORDED DTCs FROM THE ABS MODULE SELF-TEST
- Check for recorded ABS module DTCs from the self-test.
Are any DTCs recorded?
Yes
REFER to Antilock Brakes/Traction Control Systems.
No
GO to H5.
H5 RETRIEVE THE RECORDED DTCs FROM THE IC (Instrument Cluster) SELF-TEST
- Check for recorded IC (Instrument Cluster) DTCs from the self-test.
Are any DTCs recorded?
Yes
For DTC U0100, GO to Pinpoint Test AJ. Pinpoint Test AJ: DTC U0100
For all other DTCs, REFER to DTC Charts. Instrument Panel, Gauges and Warning Indicators
No
GO to H6.
H6 CARRY OUT THE SPEEDOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC (Instrument Cluster) DataLogger.
- Select the IC (Instrument Cluster) speedometer (SPD_IND) active command. Command the speedometer in 10% increments, while monitoring the speedometer. The speed indicated should increase in increments of approximately 21 km/h (13 mph) for each 10% change.
Does the speed begin at 0 km/h (0 mph) and increase by 21 km/h (13 mph) for each 10% increment?
Yes
GO to H7.
No
INSTALL a new IC (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
H7 CHECK THE PCM VSS (Vehicle Speed Sensor) INPUT
- 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 32-38 km/h (20-24 mph), 64-69 km/h (40-43 mph) and 97-103 km/h (60-64 mph) at the 3 PCM PID values?
Yes
The speedometer is operating correctly. VERIFY that the speedometer accuracy is being confirmed correctly.
No
INSTALL a new IC (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.