W T E C I I I E L E C T R O N I C C O N T R O L S T R O U B L E S H O O T I N G M A N U A L
Main code 61 indicates the ECU has detected a hot fluid condition in the output retarder. Table 57 shows what
actions are taken by the ECU at elevated retarder temperatures.
Possible causes (but not all causes) for hot fluid are:
1. Prolonged retarder use.
2. TID 2 transmission with ECU prior to Version 8A.
3. Low fluid level.
4. High fluid level.
5. A retarder apply system that allows the throttle and retarder to be applied simultaneously.
6. Cooler inadequately sized for retarder.
If the validity of the hot fluid diagnosis is in question, temperature can be checked by using a temperature gauge at the
retarder-out port or by reading retarder temperature with the Pro-Link® diagnostic tool. Another method of checking
retarder temperature is to remove the T connector at the ECU and measure resistance (Ohms) between terminals T28
and T25. Compare the resistance value to the value in Figure 621 to see if the result is within the expected operating
Use the Pro-Link® diagnostic tool to determine the software version being used.
The retarder temperature sensor is located externally on the HD retarder housing and under the plate on the MD
retarder housing. When retarder temperature reaches a preset level, a retarder hot temperature light is illuminated.
When an ECU with a version 8 calibration is used with a TransID 2 transmission, 62 XX codes are set
because the ECU does not have the proper calibrations for the TID 2 thermistors. The ECU calibration
must be updated to version 8A.
CODE 61 XX RETARDER OIL TEMPERATURE HOT