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 62 indicates the retarder temperature sensor or engine coolant sensor or circuitry is providing a signal
outside the usable range of the ECU. Main code 62 can be the result of a hardware failure or an actual extremely
high or low temperature condition.
Active Indicator Clearing Procedure:
Before troubleshooting, read Paragraph 56. Also, check the transmission fluid level.
A combination of codes 6223, 3323, and 2123 indicates a problem with one of the branches of the
common ground wire (wire 135) between the throttle and temperature sensors.
Code 62 12 can be caused when the +5V power line (wire 124) is shorted to ground or open. Wire 124
also provides power for the OLS, TPS, RMR, sump temperature sensor, and shift selectors and is
present in all three ECU connectors.
1. Check the retarder temperature or engine coolant temperature with a DDR. If a DDR is not
available, use the shift selector display to determine if the code is active (cycle the ignition on and
off at least once since the code was logged to clear the codes active indicator). If a condition that
is unreasonable for the current conditions exists, go to Step (3).
2. If Step (1) reveals that the extreme temperature indication is no longer present, the temperature
limit could have been reached due to operational or ambient temperature extremes. Proceed
cautiously as it is unlikely there is a sensor hardware fault.
3. Remove the connector at the ECU. Measure resistance between harness terminals T25 and T28 or
between harness terminals V9 and V24. Compare resistance value to chart (see Figure 521) to see
if reading is within expected operating range.
4. Disconnect the sensor connector and remove the connector at the ECU. Check the sensor and the
ECU terminals for dirt, corrosion, and damage. Clean or replace as necessary.
5. Check the temperature sensor circuit for opens (code 62 23 or 62 33), shorts between wires, and
short-to-ground (code 6212 or 62 32). If a wiring problem is found, isolate and repair.
6. If no wiring problem is found, replace the retarder or engine coolant temperature sensor.
7. If the problem recurs, use a spare wire, if available, or provide a new wire (St. Clair P/N 200153
may be used for this purpose) for the retarder or engine coolant temperature circuit.
Retarder temperature sensor failed low (45°C; 49°F)
Retarder temperature sensor failed high (178°C; 352°F)
Engine coolant sensor failed low
Engine coolant sensor failed high
CODE 61 XX RETARDER OIL TEMPERATURE HOT