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 24 indicates the ECU has detected either a high or low fluid temperature in the transmission sump (via
the sump temperature sensor in the internal harness). All shifts are inhibited when code 2412 is set (only Neutral
range operation is allowed). No upshifts are allowed above a calibration range when code 2423 is set. All inhibits
are cleared when the temperature conditions are normal. A related code is 3312 which indicates a temperature
reading outside the usable range of the sensor and indicates a probable sensor failure.
When an ECU with a version 8 calibration (CIN=0A...) is used with a TransID 2 transmission,
24 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 or later (CIN=0B).
Active Indicator Clearing Procedure:
Before troubleshooting, read Paragraph 56. Also, check the ECU input voltage.
Code 24 12:
1. If the outside temperature is between 32° C (26°F) and 7°C (+19 °F), the ECU will allow re-
verse, neutral, and second-range start operation. Only hold override upshifts are allowed. (See
Table 64 on next page.) The sump must be warmed to an acceptable temperature to avoid logging
codes and transmission diagnostic response.
Code 24 12 can result when the +5V line (wire 124) which powers the sump temperature sensor is
shorted to ground. Wire 124 also powers the TPS, OLS, RMR, retarder temperature sensor, and shift
selectors and is present in all three ECU connectors.
2. After allowing the temperatures to normalize, if ambient temperature does not match the sump
temperature reading (check using diagnostic tool), compare resistance versus sump fluid temper-
ature. Refer to Figure 58 for TID 1 thermistors and Appendix Q for TID 2 thermistors. If resis-
tance check is acceptable, then check the sensor wiring for opens, shorts, or shorts-to-ground.
3. If the sensor wiring is satisfactory, drain the fluid, remove the control module, and replace the
4. If the condition persists, replace the ECU. If replacing the ECU corrects the problem, reinstall
the original (bad) ECU to confirm that the problem is in the ECU. If the original ECU now
works, inspect the ECU connectors for any corrosion or damage that may cause an intermittent
condition. If the original problem recurs, reinstall the replacement ECU.
Sump fluid temperature cold
Sump fluid temperature hot
CODE 24 XX SUMP FLUID TEMPERATURE (Figure 57)