E039

ECM Code E39, VCC Engagement Problem

Test Conditions

1. Code E28 clear.
2. Trans in fourth gear.
3. Throttle switch open.
4. Closed Loop.
5. Not accelerating or decelerating.
6. Trans not in park or neutral.
7. Not braking.
8. VCC engaged.

Failure Conditions

1. Engine RPM too high for vehicle speed- ECM has a 9 place table of speed vs. RPM. If RPM exceeds the RPM for the speed listed in table for 30 seconds, code E39 will set. At 40 MPH, RPM should be 1650, at 50 MPH, RPM should be less than or equal to 1790, at 60 MPH, RPM should be less than or equal to 1994 RPM.

Action Taken

1. ECM turns on the "Service Soon" lamp.

Description

The viscous converter clutch solenoid is turned on when the ECM applies ground to circuit 466, "VCC Solenoid Circuit". The power for the VCC solenoid comes from the 3A "Cruise" fuse in the fuse block, flows through the VCC brake switch to pin A of five-way connector of the transmission. At pin A, current flows into the transmission to the VCC solenoid and then to the transmission overtemp switch.

The transmission overtemp switch is normally closed and open when the transmission sump temperature is 157°C or greater, to disable VCC and allow the transmission to cool. From the overtemp switch, current returns to ground through the ECM.

Code E39 is set when the engine RPM exceeds the normal value for a given speed with VCC applied. With VCC applied, the engine is coupled directly to the transmission through the VCC - almost no slippage should ever occur, so the RPM/speed ration is nearly constant. If the RPM is too high at a given speed, the ECM diagnosis the condition as the VCC is slipping or not applied and code E39 logged.

Notes on Fault Tree

1. Checking for continuity from the fuse through the solenoid to CKT 466.
2. Checking ECM's ability to ground the solenoid.
3. Circuit is OK, checking for transmission hydraulic system failure.

Notes On Intermittant

The vehicle must be driven for 30 seconds in the test conditions for code E39 to occur. This may necessitate an extended test drive, at least 15 minutes of operation at above 25 MPH.

If the customer complaint indicates that the code occurs after an extended drive, check for signs of transmission overheating. Transmission sump oil temperatures in excess of 157°C will cause the trans overtemp switch to open the VCC solenoid circuit and disable VCC.

If no trouble is found in the VCC electrical system, refer to transmission diagnosis.