P086

Diagnostic Trouble Code P086 (Part 1 Of 2):

Diagnostic Trouble Code P086 (Part 2 Of 2):

Powertrain Control Module (PCM):

CIRCUIT DESCRIPTION
The gear ratio of the transaxle is calculated from the ratio of the turbine speed over the output speed. This diagnostic test checks for gear ratio which is not possible to obtain under normal operating condition of the transaxle, if such a gear ratio is observed, Code P086 is set.

TEST CONDITIONS
1. Codes P021, P022, P024, P056, and P075 not set.
2. Engine running.
3. Vehicle speed 7 mph or greater.
4. Throttle position 11 degrees or greater.
5. Transaxle not in PARK or NEUTRAL.
6. Commanded transaxle line pressure 100 psi or greater.

FAILURE CONDITIONS
1. Gear ratio less than 2.87 or greater than 3.11 for 3 seconds.
2. Gear ratio less than 1.54 or greater than 1.71 for 3 seconds.
3. Gear ratio less than 0.95 or greater than 1.05 for 3 seconds.
4. Gear ratio less than 0.65 or greater than 0.71 for 3 seconds.
5. Gear ratio less than 2.02 or greater than 2.23 for 3 seconds.

ACTION TAKEN
1. PCM turns "ON" the Malfunction Indicator Lamp (MIL) (Service Engine Soon).
2. Powertrain Control Module (PCM) deenergizes the transaxle pressure control solenoid.
3. Torque management is disabled.
4. Maintains transaxle shift adapts at current levels.


NOTES ON FAULT TREE
1. By comparing gear box ratio (PD76) and transaxle pressure switch input (PD71), you can determine what gear the PCM was commanding and then possible causes for the gear ratio that resulted.