Fault Code 977: Alternate Shift Schedule Selector
J1939: SA 3 SPN 6160 FMI 3, 4, 5, 6, 11, 12, 13, 14, 20, 31
Overview
The Endurant HD transmission incorporates a Secondary Shift Mode feature that allows the driver to change transmission system behavior, affecting the following: shift strategy, launch or maneuvering characteristics, and ON/OFF road behaviors. The driver can choose to switch between the Primary Configuration and the Secondary Configuration based on vehicle operating conditions. The Transmission Control Module (TCM) receives a request (Input) to activate Secondary Shift Mode, determines if conditions are suitable, implements the change, and supplies a signal (Output) notification. Reference Endurant HD Driver Instructions TRDR0955 for Secondary Configuration Mode operation.
The TCM can be configured to switch to Secondary Shift Mode with messages over the vehicle Primary Data Link J1939A or from a switch circuit hardwired directly to the TCM. The TCM is equipped to receive 4 switch inputs and control 3 relay outputs that can be configured in an Input/Output (I/O) Package to support various vocational features.
If the TCM is configured to "J1939 Message" Secondary Shift Mode control messages are exchanged between the TCM and an OEM vehicle ECU. If the TCM is configured to " TCM Hardwired Switch", Secondary Shift Mode operation is controlled by Input and Output signals from a hardwired switch circuit.
Secondary Shift Mode circuit inputs and outputs are connected to the TCM in the 20-Way TCM Body Harness Connector. The Secondary Shift Mode circuit is installed by the OEM or body builder. Reference Input / Output Calibration of the Appendix for recommended Secondary Shift Mode circuit wiring diagrams.
Detection
The TCM monitors the transmission Secondary Shift Mode hardwired circuit input signal. If the signal is out of range, the fault is set Active.
Conditions to Set Fault Code Active
FMI 3 – Voltage Above Normal or Shorted High: Secondary Shift Mode circuit output signal shorted to power for 5 seconds.
FMI 4 – Voltage Below Normal or Shorted Low: Secondary Shift Mode circuit output signal shorted to ground for 5 seconds.
FMI 5 – Current Below Normal or Open Circuit: Secondary Shift Mode circuit open for 5 seconds.
FMI 6 – Current Above Normal or Grounded Circuit: Secondary Shift Mode circuit output current out of range for 5 seconds.
FMI 11 – Root Cause Unknown: The TCM detected invalid I/O Package calibration.
FMI 12 – Bad Intelligent Device: TCM has detected an internal processing error.
FMI 13 – Out of Calibration: The TCM detected invalid I/O Package calibration.
FMI 14 – Special Instructions: The TCM detected invalid I/O Package calibration.
FMI 20 – Data Drifted High: Secondary Shift Mode circuit input signal out of range (4.00–5.25 V) for 5 seconds.
FMI 31 – Condition Exists: The TCM detected invalid I/O Package calibration.
Fallback
All FMIs:
- Amber warning lamp on
- No degraded modes
- Secondary Shift Mode switch inoperative
Conditions to Set Fault Code Inactive
FMI 3: Secondary Shift Mode circuit not shorted to power for 10 seconds.
FMI 4: Secondary Shift Mode circuit not shorted to ground for 10 seconds.
FMI 5: Secondary Shift Mode circuit not open for 10 seconds.
FMI 6: Secondary Shift Mode circuit output current in range for 10 seconds.
FMI 11, 12: Key cycle and fault condition no longer exits.
FMI 13, 14, 31: Valid I/O Package calibration file is configured in TCM.
FM 20: Secondary Shift Mode circuit input signal in range for 10 seconds.
Possible Causes
FMI 3, 4, 5, 6, 20:
- Vehicle Harness - Secondary Shift Mode Circuit
- Shorted to power, shorted to ground, or open circuit
FMI 11, 13, 14, 31:
- TCM
- Invalid I/O Package calibration file configured in TCM
FMI 12:
- TCM
- Internal failure
- Software issue
Additional Tools
- None
Fault Code 977 Troubleshooting
Set vehicle parking brake and chock wheels.
Record transmission fault codes, FMIs, occurrences, and timestamps from Service Activity Report created during the Diagnostic Procedure.
If Fault Code 977 is Inactive and there are other Active vehicle or transmission fault codes, troubleshoot all Active fault codes. Go to Step V
If Fault Code 977 FMI 3, 4, 5, 6 or 20 is Active, Go to Step B
If Fault Code 977 FMI 3, 4, 5, 6 or 20 is Inactive, the intermittent nature of the fault makes it likely that the problem is in the Secondary Shift Mode switch circuit. Go to Step C
Note: Secondary Shift Mode switch circuit wiring is installed by OEM or body builder.
If Fault Code 977 FMI 11, 13, 14, 31 is Active, Contact Eaton Cummins Automated Transmission Technologies for further diagnostic instructions. For Help Line phone numbers, go to Contact Information. Go to Step V
If Fault Code 977 FMI 11, 13, 14, 31 is Inactive, Go to Step V
If Fault Code 977 FMI 12 is Active, replace Transmission Control Module (TCM). Go to Step V
If Fault Code 977 FMI 12 is Inactive, Go to Step V
Key on.
Connect ServiceRanger.
Go To “Configuration”.
Select “Secondary Configuration”.
Record "Secondary Configuration Switch" Current Value.
If “Secondary Configuration Switch” Current Value indicates “Not Configured” and Secondary Shift Mode switch circuit is properly installed and wired, select “TCM Hardwired Switch” and follow on-screen prompts. Go to Step V
If “Secondary Configuration Switch” Current Value indicates “TCM Hardwired Switch” and Secondary Shift Mode switch circuit is properly installed and wired, Go to Step C
Key on with engine off.
Connect ServiceRanger.
Go To “Configuration”.
Select “Calibrations” tab.
Record “I/O Package” Current Value.
Based on I/O package configured refer to I/O circuit schematic indicated in table. Contact OEM for repair or replacement of Secondary Shift Mode switch circuit. Go to Step V
Note: Secondary Shift Mode switch circuit wiring is installed by the OEM.
| Fault Code 977: Alternate Shift Schedule Selector (Secondary Shift Mode) | |||||||
|---|---|---|---|---|---|---|---|
| Package # and Description | 20-Way TCM Body Connector Pin(s) | Component(s) | |||||
| Input / Output Calibration Package 2: Rock Free Mode + Secondary Shift Mode | 1 | 4 | 14 | Secondary Mode Momentary Switch | Secondary Mode Relay | Secondary Mode Fuse 2 Amp | Chassis Ground |
| Input / Output Calibration Package 6: PTO 1 + Secondary Shift Mode | 1 | 4 | 5 | ||||
| Input / Output Calibration Package 7: PTO 1 + Rock Free Mode + Secondary Shift Mode | 1 | 4 | 5 | ||||
| Input / Output Calibration Package 8: PTO 1 + Reverse Output + Rock Free Mode | 1 | 4 | 14 | ||||
| Input / Output Calibration Package 11: PTO 1 + Reverse Output | 1 | 14 | 15 | ||||
| Input / Output Calibration Package 30: Reverse Output + Secondary Shift Mode | 1 | 4 | 14 | ||||
Key off.
Reconnect all connectors and verify 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 vehicle operates properly, test complete.
If Fault Code 977 sets Active, Go to Step A
If a fault code other than 977 sets Active, troubleshoot per the Fault Code Isolation Procedure Index.