What does the BOO (Brake On/Off) switch do in the E4OD circuit?

The BOO switch sends a signal to the PCM to disengage the torque converter clutch when the brake pedal is depressed. The PCM may ignore this signal if the TP signal is above closed throttle. The switch is closed with the brake pedal depressed.

What fuses power the E4OD transmission control circuit?

Fuse 13 (15A, hot in start or run) and fuse 17 (10A, hot at all times) in the fuse panel, referenced on pages 13-3, 13-9, and 13-12.

What does the TCIL (transmission control indicator lamp) mean?

It indicates that 4th gear has been disengaged, and may also flash if monitored sensors/actuators or circuits have failed.

What does the Manual Lever Position (MLP) sensor do?

It incorporates a series of step-down resistors acting as a voltage divider; the PCM monitors the voltage corresponding to the manual lever position to determine desired gear and EPC pressure. It also houses the START circuits so the vehicle can only start in PARK or NEUTRAL, and contains the backup lamp circuits, which close in reverse.

What wire colors are used for the transmission control switch and MLP sensor circuits?

The transmission control switch uses circuits 640 R/Y (power), 224 T/W, and 911 W/LG. The MLP sensor uses circuits 359 GY/R and 199 LB/Y. The BOO switch circuits are 383 R/W, 10 LG/R, and 511 LG.

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1994 Ford E4OD Transmission Wiring Diagram (Gasoline) - BOO, TCS, MLP Sensor

Ford EVTM page 30-1: E4OD gasoline transmission wiring diagram with BOO switch and TCS

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Wiring diagram for the E4OD gasoline transmission showing the brake on/off switch, transmission control switch and PCM connections.

AI caption July 2017 · Photo 293 of 386

This document is page 30-1 of a 1994 Ford wiring diagram manual covering the E4OD automatic transmission control circuit for gasoline engines. It shows power feeds from the fuse panel: fuse 13 (15A, hot in start or run) and fuse 17 (10A, hot at all times), with references to power distribution pages 13-3, 13-9, 13-12, and 13-16. The diagram traces the Brake On/Off (BOO) switch circuit (383 R/W, 10 LG/R, 511 LG through splices S236 and S240 and connectors C279/C202), which signals the PCM to disengage the torque converter clutch when the brake pedal is depressed. It also details the Transmission Control Switch with the TCIL indicator lamp (circuits 640 R/Y, 224 T/W, 911 W/LG via S215 and C275), a momentary switch allowing overdrive cancel (1st–4th or 1st–3rd shifting). The Manual Lever Position (MLP) sensor circuit (359 GY/R and 199 LB/Y through S137, S146, C103, C1012, C185) is shown as a voltage divider read by the PCM for gear selection and EPC pressure, also housing start and backup lamp circuits. PCM pins 2, 41, 32, 30, and 46 are identified, with cross-references to engine controls, turn/stop/hazard lamps, and MLP switch testing pages.

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Frequently asked questions

What does the BOO (Brake On/Off) switch do in the E4OD circuit?: The BOO switch sends a signal to the PCM to disengage the torque converter clutch when the brake pedal is depressed. The PCM may ignore this signal if the TP signal is above closed throttle. The switch is closed with the brake pedal depressed.
What fuses power the E4OD transmission control circuit?: Fuse 13 (15A, hot in start or run) and fuse 17 (10A, hot at all times) in the fuse panel, referenced on pages 13-3, 13-9, and 13-12.
What does the TCIL (transmission control indicator lamp) mean?: It indicates that 4th gear has been disengaged, and may also flash if monitored sensors/actuators or circuits have failed.
What does the Manual Lever Position (MLP) sensor do?: It incorporates a series of step-down resistors acting as a voltage divider; the PCM monitors the voltage corresponding to the manual lever position to determine desired gear and EPC pressure. It also houses the START circuits so the vehicle can only start in PARK or NEUTRAL, and contains the backup lamp circuits, which close in reverse.
What wire colors are used for the transmission control switch and MLP sensor circuits?: The transmission control switch uses circuits 640 R/Y (power), 224 T/W, and 911 W/LG. The MLP sensor uses circuits 359 GY/R and 199 LB/Y. The BOO switch circuits are 383 R/W, 10 LG/R, and 511 LG.