Fault Code 166: Secondary Accelerator Pedal Position
J1939: SA 3 SPN 29 FMI 9, 13, 19
Overview
The Transmission Control Module (TCM) receives the vehicle's Secondary Accelerator Pedal Position message over the Secondary Data Link. The Primary Accelerator Pedal Position provides the TCM with the driver's demand to launch and accelerate the vehicle. The TCM also receives a Secondary Accelerator Pedal Position message over the Secondary Data Link. The Secondary Accelerator Pedal Position message allows the vehicle to operate in a degraded mode in the event the Primary Accelerator Pedal Position message is not available. The Secondary Accelerator Pedal Position message is contained within the 20-Way TCM Body Harness Connector.
Detection
The TCM monitors the Secondary Accelerator Pedal Position message. If an invalid message is received, the TCM sets the fault code active.
Conditions to Set Fault Code Active
FMI 9 - Abnormal Update Rate: Secondary Accelerator Pedal Position message not received for 5 seconds.
FMI 13 - Out of Calibration: Secondary Accelerator Pedal Position message not available for 5 seconds.
FMI 19 - Received Network Data in Error: Secondary Accelerator Pedal Position message invalid for 5 seconds.
Fallback
All FMIs:
- Amber warning lamp on
- No degraded modes
- If Fault Code 135, 165, 166 and 177 are Active and the transmission is in neutral:
- Non neutral modes prohibited
- PTO mode prohibited
- If Fault Code 135, 165, 166 and 177 are Active, the vehicle is moving and the transmission is in a gear higher than the lowest available start gear:
- Red stop lamp on
- Clutch engagement prohibited, vehicle may coast to a stop
- Transmission downshifts to lowest available start gear
- Non neutral modes prohibited
Conditions to Set Fault Code Inactive
All FMIs: Secondary Accelerator Pedal Position signal received and valid for 10 seconds.
Possible Causes
All FMIs:
- Vehicle components
- Module(s)
- Accelerator Pedal Position Sensor and/or wiring
- J1939 Data Link
Additional Tools
- None
Fault Code 166 Troubleshooting
Set vehicle parking brake and chock wheels.
Record the transmission fault codes, FMIs, occurrences, and timestamps from the Service Activity Report created during the Diagnostic Procedure.
If Fault Code 166 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V
If Fault Code 166 FMI 13 is Active, refer to OEM and enable vehicle Secondary Accelerator Pedal Position SPN 29. Go to Step V
If Fault Code 166 FMI 13 is Inactive, Go to Step V
If Fault Code 166 FMI 9 or 19 is Active or Inactive, Go to Step B
Key on with engine off.
Connect ServiceRanger.
Go To “Data Monitor”.
Select “Position”.
Select “Percent accelerator pedal position 2”.
Select all of the “-29” SPN sources.
Note: Not all sources will indicate a value.
Monitor Percent accelerator pedal position 2 and record reading in table.
Depress and hold the accelerator pedal.
Monitor Percent accelerator pedal position 2 and record reading in table.
Compare reading(s) in table.
If readings are out of range, refer to OEM guidelines for repair or replacement of the Secondary Accelerator Pedal Position signal message. Go to Step V
If readings are in range, no fault was found. The intermittent nature of the fault makes it likely that the problem is in the Secondary Accelerator Pedal Position signal message. Contact OEM for further diagnostic instructions. Go to Step V
| Accelerator Pedal State | Parameter | Range | Reading(s) |
|---|---|---|---|
| Released | 29 - Percent accelerator pedal position 2 | 0% | |
| Depressed | 29 - Percent accelerator pedal position 2 | Greater than 0% |
Key off.
Reconnect all connectors and verify that all components are properly installed.
Key on with engine off.
Connect ServiceRanger.
Go to “Fault Codes”.
Select “Clear All Faults”.
Operate vehicle and attempt to reset the fault code or duplicate the previous complaint.
Check for fault codes using ServiceRanger.
If no fault codes set and the vehicle operates properly, test complete.
If Fault Code 165 sets Active during operation, Go to Step A
If a fault code other than 165 sets Active, troubleshoot per Fault Code Isolation Procedure Index