P1813

TRANSMISSION FLUID TEMPERATURE SENSOR, SHORTED TO GROUND (P1812), OR OPEN CIRCUIT OR SHORTED TO B+ (P1813).





Fault Symptom.
Disturbances in lock-up and gear-shifting functions at higher temperatures.

Conditions.
P1812: Shorting to ground.
P1813: Shorting to battery voltage or open circuit and if the transmission control module reads a fluid temperature lower than -10 °C when the engine has been running for about 5 minutes.

Diagnostic Help.
The current fluid temperature can be checked using an ISAT scan tool.
Select "READ FUNCTIONS".
Select "OIL TEMPERATURE".
With the engine and transmission warmed up, nominal fluid temperature is about 80 °C and about 1.1 V.

Check The Wiring.
Intermittent faults may occur as a result of temporary short circuits and breaks in the wiring. Jiggle the leads at several places and in different directions to reveal any faults in the wiring harness, including connectors. Observe the multimeter, test lamp or ISAT scan tool while carrying out this check.





Procedure.
1. Check the fluid temperature sensor's connection to ground

Unplug connector H16-3 (16-pin connector located behind the battery) and connect a test lamp to pin 12 of the female connector and battery positive (B+).

Does the lamp light up?

YES: Continue with point 2.
NO: Repair or replace the wiring (including connectors) between connector H16-3, pin 12 of the female connector, and grounding point G4.

2. Check the transmission control module's signal input
- Connect the ISAT scan tool.
- Turn the ignition switch to the ON position.
- Select "READ FUNCTIONS".
- Select "OIL TEMPERATURE".

^ With pin 12 open, the ISAT scan tool's display should show a reading of less than -40 °C.
^ With a jumper lead connected between pins 4 and 12, the ISAT scan tool's display should show a reading of more than 175 °C.

Are both readings OK?

YES: Continue with point 3.
NO: Proceed to point 4.





3. Check The Wiring

Check the continuity of the wiring between

- pin 4 of connector H16-3 and the temperature sensor's connector (the pin marked 20).
- pin 12 of connector H16-3 and the temperature sensor's connector (the unmarked pin).

Is the wiring OK?

YES: Change the temperature sensor and proceed to point 5.
NO: Rectify the fault and proceed to point 5.





4. Check The Wiring connected to the transmission control module

Check the continuity of the wiring between pin 4 of female connector H16-3 and pin 33 of the transmission control module.

Is the wiring OK?

YES: Continue with point 5.
NO: Rectify the fault and continue with point 5.

5. Final check

Clear the diagnostic trouble code, drive the car on test at varying engine loads and speeds for 5 minutes and obtain readouts of any diagnostic trouble codes that are generated.

Has the diagnostic trouble code recurred?

YES: Continue as described under "Before Changing A Control Module". Before Changing A Control Module
NO: The remedial action taken was correct.