E039

TEST CONDITIONS
1. Codes EO26, EO27, EO31, EO32, EO34, EO56, EO57, and EO59 not set;
2. Transmission in fourth gear;
3. Throttle switch open;
4. Engine control in closed loop;
5. Viscous Converter Clutch (VCC) commanded;
6. Transmission not in park/neutral;
7. Brake off;
8. Trans temp less than or equal to 151°C.

FAILURE CONDITIONS
Engine RPM too high for vehicle speed for 10 seconds.

ACTION TAKEN
1. ECM turns on "Engine Control System Fault" telltale;
2. ECM commands BCM to display "Service Soon" message on Driver Information Center (DIC);
3. VCC is disabled to the entire ignition cycle.

DESCRIPTION
The viscous converter clutch solenoid controls hydraulic fluid for VCC apply and release. The solenoid is energized when the ECM provides a ground on CKT 422. Power to the solenoid comes from the IGN switch through the Brake switch to Pin A of the transmission connector. The VCC overtemp switch (located in the transmission) is normally closed and opens when transmission fluid is 157°C or greater and disables VCC to allow the transmission oil to cool.

Code EO39 is set when the engine RPM exceeds the normal RPM value at a given speed with the VCC applied. When the VCC is applied, the engine is coupled directly to the transmission through the VCC. Almost no slippage should occur, so the RPM/speed ratio is nearly constant. If RPM is too high at a given speed, the ECM diagnosis the condition as the VCC slipping or not engaged and Code EO39 is set.

Notes on Fault Tree
1. Checking for continuity from the fuse through the solenoid to CKT 422.
2. Checking the ECM's ability to ground the solenoid.
3. Circuit is OK, checking for proper transmission hydraulic operation.
4. Checking for open in CKT 422.

Notes on Intermittents
The vehicle must be driven for 10 seconds in the test conditions for Code EO39 to occur.

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 temperature switch to open the VCC solenoid circuit and disable VCC.

If no trouble is found in the VCC electrical system, refer to Transmission Diagnosis. Testing and Inspection

See Viscous Converter Clutch System for VCC control system operation description and performance check. Computers and Control Systems