As we are all aware, the Ford E4OD transmission has a soft shift problem that causes premature wear to the clutches and bands. There are several add ons on the market that correct this problem, but at considerable expense.
After considerable research I have designed a CHEAP cure.
I’ll start with a little explanation of how the E4OD is controlled by the ECM (electronic control module). All solenoids in the transmission have +12 volts applied to one side of their coils at all times. The ECM then controls the –12 volts to make the transmission function. If you were to remove the control wire from the EPC (electronic pressure control) solenoid, the line pressure would go to maximum pressure and cause an overly firm shift. Through the use of a voltage divider you can control how firm the shifts are.
Note that Ford switched from 1-ohm coils to 10-ohm coils in 1994 or 95. The resistor values given are for E4Ods with 10-ohm coils. If you check the voltage (see diagram) across points A & B there should be approximately 4.9 volts and across points A & C there should be approximately 2.0 volts. If the voltage between points A & B is reduced below 3 volts the ECM will think there is a fault and blink the light continually on the end of the shift stalk.
All quoted voltages are with resistors installed and engine running. Leave transmission in park when checking voltages. The wire colors are for a 95 F53 E4OD. I elected to add the resistors to the wiring harness on top of the engine. It’s much easer working under the doghouse than lying on your back with soldering iron in hand.
The Radio Shack catalog doesn’t show 5 ohm 10 watt resistors, but they do have 10 ohm 10 watt resistors in a 2 pack. By simply putting 2 10-ohm resistors in Parallel you will have a 5-ohm resistor. Part # 271-132.
