CODE 64 XX -- RETARDER MODULATION REQUEST DEVICE FAULT

WTEC III ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL

CODE 64 XX -- RETARDER MODULATION REQUEST DEVICE FAULT

The datalink for throttle sensor or engine coolant temperature must have been recognized by auto detect or

manually selected using the Pro-Link (see WTEC III Pro-Link Manual) before these codes can be logged.

Main code 66 indicates the ECU is expecting to get its throttle position signal or engine coolant signal across a

serial communication interface from a computer-controlled engine. Either the engine computer is not sending the

throttle or engine coolant information or the wiring between the engine and transmission computers has failed.

Code 66 00 can occur when the transmission ECU remains powered when the engine ECM is powered down. The

transmission sees this as a communication link failure.

Main

Code

Subcode

Meaning

SCI (Serial Communication Interface) fault

SCI Engine coolant source fault

Active Indicator Clearing Procedure:

Power down

Manual

Self-clearing

Troubleshooting:

1. Check for a throttle signal or engine coolant signal from the engine to the transmission, an engine

computer malfunction, an engine throttle fault, or an engine coolant fault.

NOTE:

Throttle position data sent from a computer-controlled engine may register a low number of counts on

the DDR, but the counts will not change as throttle percentage is changed.

2. Check wires 142 and 151 between the engine and transmission ECU for an open or short. Check

that all connectors are clean and tightly connected.

NOTE:

These codes can also be set if J1939 communications fail. Check wires 183-S13, 184-S29, and

182-S12 for opens or shorts.

3. Use the Pro-Link to see if the ECU is receiving power when it should not.

0021 00118