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Ford 4R70W Transmission Wiring Diagram - PCM, BOO, TCS, MAF & PSOM Circuits
Reference · 1992-1996 BroncoAll 411 wiring diagrams
1994 4R70W transmission wiring diagram showing the PCM, transmission control switch, BOO switch, MAF sensor and connectors.
Part of 1992-1996 Ford Bronco Wiring Diagrams
This document is page 29-1 of a Ford wiring diagram set covering the 4R70W automatic transmission control circuit (page marked "94"). It shows the powertrain control module (PCM) inputs related to transmission operation. Power feeds come from fuse panel fuse 17 (10A, hot in run and start, circuit 640 R/Y) and fuse 13 (15A, hot at all times, circuit 383 R/W), with references to Power Distribution pages 13-3, 13-12 and 13-16. Components diagrammed include the Transmission Control Switch (a momentary switch with TCIL lamp allowing 1st-through-4th or 1st-through-3rd shifting), the Brake On/Off (BOO) switch (closed with pedal depressed, used to disengage the torque converter clutch), the Programmable Speedometer/Odometer Module (PSOM, page 60-7, circuit 679 GY/BK providing vehicle speed input for upshift scheduling), the Mass Air Flow (MAF) sensor (circuits 967 LB/R and 968 T/LB, used for EPC pressure and shift/TCC scheduling), the Intake Air Temperature (IAT) sensor (circuit 743 GY, used for EPC pressure), and the Speed Control Servo/Amplifier Assembly. Wire circuit numbers, colors, connector labels (C275, C279, C202, C185, C130, C101, C164, C216, C252), splices (S215, S232, S236, S240) and PCM pin numbers (41, 32, 3, 2, 50, 9, 25) are all identified, along with cross-references to related diagram pages.
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Frequently asked questions
- What fuses power the 4R70W transmission control circuit in this diagram?
- Fuse 17 (10A) in the fuse panel, hot in run and start (fuse panel page 13-3), feeding circuit 640 R/Y; and fuse 13 (15A), hot at all times (fuse panel page 13-12), feeding circuit 383 R/W.
- What does the Transmission Control Switch do?
- It is a momentary contact switch that signals the PCM to allow automatic shifts from 1st through 4th or from 1st through 3rd gears. Its TCIL indicates that 4th gear has been disengaged and may also flash if monitored sensors/actuators or circuits have failed.
- What is the function of the Brake On/Off (BOO) switch in this circuit?
- The BOO switch, closed with the brake pedal depressed, sends a signal on circuit 511 LG to the PCM to disengage the torque converter clutch. The signal may be ignored by the PCM if the TP signal is above closed throttle.
- What wire circuit carries the vehicle speed signal from the PSOM to the PCM?
- Circuit 679 GY/BK runs from the PSOM (pin 12) through C252, C202, S232 and C185 (pin 3) to the PCM; it is used as Vehicle Speed Input to determine upshift scheduling.
- Which sensors in this diagram affect EPC pressure?
- The Mass Air Flow (MAF) sensor (circuits 967 LB/R and 968 T/LB) is used in determining EPC pressure, shift, and torque converter clutch scheduling, and the Intake Air Temperature (IAT) sensor (circuit 743 GY) is used in determining EPC pressure.
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