Pinpoint Test G: Incorrect Speedometer Indication
Instrumentation, Message Center and Warning Chimes
Pinpoint Test G: Incorrect Speedometer Indication
Normal Operation
The PCM calculates the vehicle speed from the transaxle Output Shaft Speed (OSS) sensor input and from the tire size and axle ratio configuration in the PCM Vehicle Identification (VID) block. The PCM provides the Instrument Panel Cluster (IPC) with the vehicle speed data over the High Speed Controller Area Network (HS-CAN) bus. The IPC (Instrument Panel Cluster) monitors the vehicle speed input and commands the speedometer with a corresponding movement of the pointer.
The IPC (Instrument Panel Cluster) 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 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 speedometer accuracy are incorrect tire size, tire size configuration and axle ratio configuration.
If the vehicle speed data is missing for 5 seconds or less or if the IPC (Instrument Panel Cluster) receives invalid vehicle speed data for 5 seconds or less, the IPC (Instrument Panel Cluster) defaults the speedometer to the last setting, based upon the last known good vehicle speed message. If the IPC (Instrument Panel Cluster) does not receive the vehicle speed data from the PCM for more than 5 seconds, the IPC (Instrument Panel Cluster) 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 (Instrument Panel Cluster) for 5 seconds or longer, the IPC (Instrument Panel Cluster) sets DTC U0401:68 and defaults the speedometer to 0 km/h (0 mph).
NOTE: If DTC U0100:00 is set in the IPC (Instrument Panel Cluster), other observable symptoms may be an inoperative tachometer, temperature gauge or odometer.
This pinpoint test is intended to diagnose the following:
- Axle ratio configuration
- Tire size configuration
- PCM concern
- IPC (Instrument Panel Cluster)
PINPOINT TEST G : INCORRECT SPEEDOMETER INDICATION
G1 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 G2.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.
G2 CHECK THE 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.
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 tire size and axle ratio parameters correctly configured?
Yes
GO to G3.
No
CONFIGURE the PCM for the correct tire size. TEST the system for normal operation.
G3 RETRIEVE THE RECORDED DTCs FROM THE PCM KOEO (Key ON Engine OFF) SELF-TEST
- Check for recorded PCM DTCs from the Key ON Engine OFF (KOEO) self-test.
Are any PCM DTCs recorded?
Yes
DIAGNOSE all PCM DTCs first. REFER to Computers and Control Systems Information.
No
GO to G4.
G4 RETRIEVE THE RECORDED DTCs FROM THE IPC (Instrument Panel Cluster) SELF-TEST
- Check for recorded DTCs from the IPC (Instrument Panel Cluster) self-test.
Are any DTCs recorded?
Yes
For DTC U0100:00, GO to Pinpoint Test AR. Pinpoint Test AR: DTC U0100:00
For DTC U0401:68, RETRIEVE and REPAIR all non-network DTCs in the PCM and other modules on the network. REFER to Computers and Control Systems Information and 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.
G5 CARRY OUT THE IPC (Instrument Panel Cluster) SPEEDOMETER ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Select the IPC (Instrument Panel Cluster) speedometer (SPDOMETER) active command and command the speedometer in increments of approximately 32.2 km/h (20 mph). Observe the speedometer. The speedometer starts at 0 km/h (0 mph) and moves approximately 32.2 km/h (20 mph) for each increment.
Does the speedometer begin at 0 km/h (0 mph) and move by approximately 32.2 km/h (20 mph) for each increment?
Yes
GO to G6.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.
G6 CHECK THE PCM VSS (Vehicle Speed Sensor) 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 (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) . TEST the system for normal operation.