P089

Circuit Description

Transaxle pressure is modified by an adaptive modifier used to control the gear shift execution time. This diagnostic test checks the shift execution and the time it takes to accomplish it. If it takes longer than 0.55 second and the adaptive modifier cannot shorten this time, the counter will be incremented. When the counter reaches 5, Code P089 will set.

Test Condition(s)

1. Codes P021, P022, P024, P056, P057, P059, and P075 not set.
2. Vehicle speed 10 mph or greater.
3. Throttle position 15.7 degrees or greater.
4. Transaxle temperature 90°C or greater.

Failure Condition(s)

Case I
1-2 shift time 0.55 second or greater and adapt cannot shorten shift time for 5 shifts.

Case II
2-3 shift time 0.55 second or greater and adapt cannot shorten shift time for 5 shifts.

Case III
3-4 shift time 0.55 second or greater and adapt cannot shorten shift time for S shifts.

Action Taken

1. PCM turns 'ON' the 'SERVICE ENGINE SOON' MIL.
2. PCM deenergizes the transaxle pressure control solenoid.

Notes on Fault Tree

1. Perform the pressure gage installation procedure.
2. Using customer information to diagnose which shift caused code to set.
3. Code P089 snapshot information can be used to determine which shift the 'Long Time' occurred on. Throttle position, MAP value, and vehicle speed should provide enough information to either directly conclude when the faulty shift occurred or allow the failure conditions to be recreated during a vehicle test drive. It is important to note that the failure must occur five times before Code P089 will set. However, monitoring PCM parameter PD82 while test driving will show which shift is taking longer than 0.55 seconds.

Notes on Intermittents

Due to the complexity of the 4T80-B transaxle, an intermittent Code P089 will be very difficult to diagnose. It may be wise to hold off maintenance until a specific problem is identified.