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DTC P086:

Transmission Control Circuit:

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 CONDITION(S):
1. Codes P021, P022, P024, P056, and P075 not set.
2. Engine running.
3. Vehicle speed 7 mph or greater.
4. Throttle position 15.7 degrees or greater.
5. Transaxle not in PARK or NEUTRAL.
6. Commanded transaxle line pressure 100 psi or greater.

FAILURE CONDITION(S):
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 2.22 for 3 seconds.

ACTION TAKEN:
1. PCM turns "ON" the "SERVICE ENGINE SOON" MIL
2. PCM deenergizes the transaxle pressure control solenoid.

Line Pressure Chart:

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