P1813

P1812, P1813, P0711
Fluid temperature sensor. Faulty (P0711) Fluid temperature sensor, short circuit to ground (P1812) alternatively open circuit or short circuit to B+ (P1813).

Fault symptoms
CHECK GEARBOX warning lamp on.

Conditions

P0711: During the first 15 minutes of running, the fluid temperature increases or decreases with less than 5 °C.
P1812: Shorting to ground for 5 minutes.
P1813: Open circuit or short circuit to B+ for 15 min.

Diagnostic help
The diagnostics instrument can be used to obtain a reading of the transmission fluid temperature.

If the transmission fluid temperature sensor is in perfect working order the diagnostics instrument should show the current fluid temperature.

Neither position P nor N should be selected during the test. The timer for the diagnostic trouble codes is then reset to zero.

Check the wiring
Jiggle the wiring harness at several points and in different directions to reveal intermittent breaks and short circuits in the various leads. Observe the multimeter, test lamp or diagnostic instrument while carrying out this check.






Diagnostic procedure

1 Check the fluid temperature sensor ground connection
- Unplug the 2-pin temperature sensor connector.
- Connect a test lamp between B+ and pin 2 on the 2-pin female connector.
The test lamp should light up.

All OK?
YES
Continue with step 2.
NO
Rectify the relevant lead and continue with step 3, final check.






2 Check the control module's fluid temperature sensor input
- Unplug the 2-pin temperature sensor connector.
- Connect a diagnostic tool.
- Turn the ignition to the ON position.
- Read "Fluid temperature."
The reading should be approx. -4O°C
- Connect a jumper lead between the 2-pin connector pins 1 and 2.
The reading should be 175°C

All OK?
YES
Change the fluid temperature sensor and continue with step 3, final check.
NO
Rectify the relevant lead and continue with step 3, final check.






3 Final check
- Clear all diagnostic trouble codes in the system
- Perform a driving cycle:
- Drive the car at varying engine loads and engine speeds for at least 15 minutes.
- Evaluate the driving cycle:
- Make sure the trouble code has not recurred.

Has the trouble code recurred?
YES
Continue with "Before changing a control module," see Fault diagnosis, general, "Before changing a control module." Tech 2 Scan Tool

NO
The steps taken to rectify the fault were correct.