DTC 142

DN. DTC 1-4-2
1-4-2 Open-circuit in fluid temperature sensor circuit

Principle of operation

The sensor supplies a signal which is used for many functions, such as temperature-controlled lock-up and activation of high-temperature programs. The sensor resistance varies with temperature, from 2000 Ohm at 0°C (32°F) to 75 Ohm at 100°C (212°F).

Fault description

An open-circuit is present in the circuit between the fluid temperature sensor and TCM, or the sensor is faulty.
Troubleshooting should indicate if the fault is in the wiring, sensor or TCM. Note that approx. 10 minutes must elapse after starting (test drive) before DTC can be recorded.





Circuit description

The circuit consists of the TCM, three connectors and the fluid temperature sensor on the transmission.





1
Checking fluid temperature

Check in test mode 5 that indicated fluid temperature is reasonable. Displaying & Reading Trouble Codes

If using the DLC manually, see response code conversion table in for test mode 5.





2
Measuring resistance of fluid temperature sensor and leads

- Switch off ignition.
- Connect break-out box to wiring.

Connect ohmmeter between # 6 (OT) and # 7 (OTG).

- If instrument reading is in accordance with tabulated values, sensor and leads are OK.
In this case, fault is due to intermittent fault. Return to Testing and Inspection. Diagnostic Procedures

- If instrument indicates other value, proceed to following step.





3
Measuring resistance of fluid temperature sensor

- Switch off ignition.
- Measure at connector D on transmission (solenoid side).

Connect ohmmeter between terminal 3 (OT) and 4 (OTG).

- If instrument indicates value other than tabulated value, sensor is faulty. Replace sensor.
- If instrument indicates value as per table, sensor is OK.
Check leads for open-circuit and short-circuit to ground. also check for poor connections.

Return to Testing and Inspection. Diagnostic Procedures