: 94 Concourse Shifting Problem



94CONCOURSE
12-02-03, 10:35 PM
I have a 94 Concourse with 140K miles. When the vehicle reaches approximately 55 mph it downshifts to, I believe, 2nd gear and the service engine soon light comes on. The codes read P039 - torque converter clutch engagement problem, P089 - long shift and maximum adapt (transmission pressure control), P094 - transaxle shift "A" solenoid problem (vehicle speed sensor). Any recommendations?

epanightmare
12-04-03, 08:49 PM
I have a 94 Concourse with 140K miles. When the vehicle reaches approximately 55 mph it downshifts to, I believe, 2nd gear and the service engine soon light comes on. The codes read P039 - torque converter clutch engagement problem, P089 - long shift and maximum adapt (transmission pressure control), P094 - transaxle shift "A" solenoid problem (vehicle speed sensor). Any recommendations?
I Hope some of this info helps, but I think that your transmission is probably on it's way out. You can try replacing the electric solenoids in the trans but if you drop the trans pan and find alot of black sediment or metal shavings then it's probably time to replace it.
:coffee:
P094
CIRCUIT DESCRIPTION
This diagnostic test checks for a transaxle shift "A" solenoid problem by monitoring the commanded gear verses the transaxle gear ratio. If the gear ratio falls outside of the range for a given gear, Code P094 will set.

TEST CONDITIONS

Codes P021, P022, P024, P028, and P056 not set. Transaxle pressure switch indicating transaxle in D1, D2, D3 or D4. Engine running. Vehicle speed 7 mph or greater. Throttle position of 11 degrees or greater.FAILURE CONDITION(S)
Case 1


Gear ratio between 1.54 and 1.71 for 5 seconds. First gear commanded.Case 2


Gear ratio between 2.87 and 3.11 for 5 seconds. Second gear commanded.Case 3


Gear ratio between 0.67 and 0.71 for 5 seconds. Third gear commanded.Case 4


Gear ratio between 0.95 and 1.05 for 5 seconds. Fourth gear commanded.ACTION TAKEN


Powertrain Control Module (PCM) turns "ON" the (MIL) (Service Engine Soon). PCM allows only second gear when any forward gear is selected.NOTES ON FAULT TREE


Checking if Code P117 is also set because it can cause the transaxle problems. Checking if Shift "A" solenoid is "HI" when it should be "LO" or if it is "LO" when it should be "HI." Checking if PCM is operating correctly and setting code falsely. Checking if CKT 741 is open to C129. Checking if CKT 1222 (engine harness side) is open. Checking CKT 1222 (trans. harness side) for a short to ground inside transaxle. Checking for an open inside transaxle. Checking CKT 1222 (trans. harness side) for a short to voltage inside transaxle. Checking CKT 1222 (engine harness side) for a short to voltage from C129 to PCM. Possible causes of getting 4th gear when 3rd gear is commanded. Possible causes of getting 3rd gear when 4th gear is commanded. Possible causes of getting 2nd gear when 1st gear is commanded. Possible causes of getting 1st gear when 2nd gear is commanded.
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 CONDITIONS

Codes P021, P022, P024, P056, P057, P059, and P075 not set. Vehicle speed 10 mph or greater. Throttle position 15.7 degrees or greater. Transaxle temperature 90C or greater.FAILURE CONDITIONS
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 5 shifts.

ACTION TAKEN


Powertrain Control Module (PCM) turns "ON" the (MIL) (Service Engine Soon). PCM deenergizes the transaxle pressure control solenoid.NOTES ON FAULT TREE
(Part 1 of 2)


Refer to HYDRA-MATIC 4T80-E Automatic Transaxle Diagnosis for pressure gage installation procedure. (Part 2 of 2) Using customer information to diagnose which shift caused code to set. Code P089 snapshot information can be used to determine which shift the "Long Time" occurred on. Throttle position (TP) , Manifold Absolute Pressure (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-E 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.

P039
CIRCUIT DESCRIPTION
The Torque Converter Clutch (TCC) solenoid controls the hydraulic fluid for apply or release. The diagnostic test checks for a torque converter clutch not engaged or slipping condition by monitoring the slip speed. Slip speed is the difference between engine speed and transaxle turbine speed. When the TCC is applied, the engine is coupled directly to the transaxle through the TCC. Almost no slippage should occur, so the slip speed is nearly 0. If rpm is too high at a given speed, the Powertrain Control Module (PCM) diagnosis the condition as the TCC slipping or not engaged and Code P039 is set.

TEST CONDITIONS

Codes P024, P026, P027, P028, P031, P032, P034, P056 and P075 not set. Transaxle in 3rd or 4th gear. Engine running. tcc commanded "ON" (100%). Transaxle not in park or neutral. tps open. Delivered torque from engine not 32 ft lb or less (coast down condition). Delivered torque from engine not 508 ft lb or more (engine under extreme load (Example: towing a trailer or wide open throttle).FAILURE CONDITIONS
3.71 Final Drive (VIN 9) - Slip speed 48 rpm or greater for 4.5 seconds.
3.11 Final Drive (VIN Y) - Slip speed greater than acceptable value based on engine torque delivered for 4.5 seconds. Refer to chart in accompanying image for acceptable tcc slip values.

ACTION TAKEN


PCM turns "ON" the (MIL) (Service Engine Soon). 2. TCC is disabled for the entire ignition cycle.NOTES ON FAULT TREE
(Part 1 of 2)


Testing Torque Management Brake Switch input to the PCM PI71. If test passes, the display will change from HI 0 to HI X. If test fails, the display will not change. Checking for an open in CKT 420 between C129 and C101. (Part 2 of 2) Checking for open or shorts inside the transaxle. The resistance should be between 10 and 40 ohms. Checking if CKT 422 is open or if the PCM is unable to control the output. Checking PCM's ability to control the TCC output. Checking if TCC is operating correctly by checking amount of TCC slip when clutch is engaged.NOTES ON INTERMITTENTS
Intermittent code P039 setting may be caused by delayed TCC engagement (usually the first apply after a cold start) or by TCC slippage during high engine load conditions. Delayed TCC engagement can be checked using PCM 0utput Override PS01 (TCC Solenoid) to disengage and engage TCC and time how long it takes TCC to engage by watching PCM Data PD73 (Torque Converter Slip Speed). Delays of over 5 seconds may cause the code to set. TCC slippage during high load conditions can be determined by looking at code P039 Snapshot Data. High throttle angle (PD01), MAP (PD02), and engine coolant temperatures (PD04) may indicate a high load condition. Duplicating the high load conditions may cause the code setting conditions to occur.