GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 DeVille 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T80-E 🢒 DTC P1868

Circuit Description

Transmission fluid life is determined by monitoring transmission fluid temperature over a period of time. The PCM calculates transmission fluid life based on a set of temperature ranges stored in PCM memory. As the vehicle is driven, a counter increments. The rate at which the counter increments depends on the temperature range in which the transmission is currently operating in. The higher the temperature range, the faster the counter increments. As the counts increment, the PCM will begin to decrease the fluid life percentage from 100, high fluid life, to 0, low fluid life.

If the PCM detects a calculated transmission oil life of 10 percent or less, then DTC P1868 sets. DTC P1868 is a type C DTC.

Conditions for Running the DTC

No TFT DTCs P0711, P0712, or P0713.

Conditions for Setting the DTC

The calculated transmission oil life remaining is 10 percent or less.

Action Taken When the DTC Sets
    • The PCM does not illuminate the malfunction indicator lamp (MIL).
    • CHANGE TRANSMISSION FLUID displays on the driver information center (DIC).
    • The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
    • The PCM stores DTC P1868 in PCM history.

Conditions for Clearing the DIC/DTC
    • The PCM clears the DIC when the condition no longer exits.
    • A scan tool can clear the DTC.
    • The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
    • The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

Diagnostic Aids

Inspect the transmission cooling system for possible blockage and restrictions.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step changes the AT fluid and filter. It is important to reset the oil life monitor after the fluid and filter are replaced.

DTC P1868

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

  3. Record the DTC Failure Records.
  4. Clear the DTC.
  5. Change the AT fluid and filter.

    6. Refer to Side Cover, Gasket, and Filter Removal in the 4T80-E section of the Transmission Unit Repair Manual.

  6. Inspect the AT fluid for correct level.
  7. Add new fluid as necessary.
  8. Use the scan tool in order to reset the transmission oil life monitor to 100%.

Did you complete the above procedures?

--

Go to Step 3

--

3

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Ensure that the transmission oil life monitor displays 100%.
  4. Select Specific DTC.
  5. Enter DTC P1868.

Has the test run and passed?

--

Go to Step 4

Go to Step 2

4

With the scan tool, observe the stored information, capture info. and DTC info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List in Engine Controls

System OK