ECM Code EO39: VCC Engagement Problem (2 Of 2): Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.

Test Number 1) At this point, electrical integrity of system has been verified. A road test is not required to verify operation of VCC.

Test Number 2) If no RPM change is noticed, VCC is not applying. Perform standard hydraulic system pressure test.

Test Number 3) If engine speed does not increase 100 RPM or more, VCC is applying. However, since Code EO39 is stored, ECM has detected excessive slippage at some time. To induce conditions which may cause excessive slippage, drive vehicle under heavy load, such as uphill. If no hills are present in test drive area, apply parking brake while driving.

Test Number 4) Excessive slippage is indicated if engine speed loaded is 100 RPM or more greater than engine speed unloaded at the same vehicle speed. A Code 39 may be set by slippage in the 2nd and/or 4th clutches since they are the only clutches that transmit torque in 4th gear. If 2nd clutch is slipping, a slip or flare should occur during 1-2 upshifts.

Test Number 5) Normal VCC slippage is 0-75 RPM when VCC is engaged and engine is loaded. Compare engine RPM and MPH readings obtained in the road test with those in the flow chart table.

Test Number 6) To check 4th gear slippage, note engine speed increase when downshifted OD to 3 at 50-60 MPH with VCC engaged.

Test Number 7) If RPM increase is less than 650 RPM, there is slippage in 4th clutch.

Test Number 8) If engine speed increases 650-750 RPM when shifted from OD to 3, 4th clutch is not slipping and there is excessive slippage in VCC.