What wire color is the EPC solenoid circuit on the 4R70W transmission?

The Electronic Pressure Control (EPC) solenoid uses circuit 925 with a W/Y (white/yellow) wire, passing through connector C110 to the PCM.

What circuit and wire color do the 4R70W shift solenoids use?

Shift Solenoid #1 uses circuit 237, O/Y wire (PCM pin 51); Shift Solenoid #2 uses circuit 315, P/O wire (PCM pin 52). The shift solenoids provide gear selection of first through fourth by controlling pressure to the shift valves.

What does the transmission fluid temperature sensor do according to this diagram?

The PCM monitors the voltage drop across a temperature-sensitive thermistor to determine transmission fluid temperature, used to adjust shift schedules and torque converter engagement when fluid is cold, and to adjust EPC pressure for temperature. It's on circuit 923, O/BK wire, to PCM pin 49.

What is the function of the torque converter clutch solenoid?

It controls the apply and release pressure to the torque converter clutch control valve. It's wired on circuit 480, P/Y wire, to PCM pin 53.

Which connectors are in the 4R70W transmission wiring harness?

The diagram shows connector C1049 at the transmission, plus in-line connectors C103, C110, and C185 between the transmission and the PCM.

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Ford 4R70W Transmission Wiring Diagram - Solenoids, EPC & PCM Circuits (Pg 29-2)

1994 4R70W transmission wiring diagram with shift solenoids and EPC solenoid

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1994 4R70W transmission wiring diagram showing shift solenoids, torque converter clutch solenoid, EPC solenoid and fluid temperature sensor to the PCM.

AI caption July 2017 · Photo 290 of 386

This is a scanned wiring diagram page (labeled "29-2 4R70W Transmission", section 94) from an automotive electrical/vacuum troubleshooting manual, showing the electronic control wiring for the Ford 4R70W automatic transmission. The diagram maps five transmission components — Transmission Fluid Temperature Sensor (pin 5), Torque Converter Clutch Solenoid (pin 3), Shift Solenoid #2 (pin 6), Electronic Pressure Control (EPC, pin 10), and Shift Solenoid #1 (pin 1) — through connectors C1049, C103, C110, and C185 to the Powertrain Control Module (PCM, referenced to pages 24-3 and 24-4). Circuit numbers and wire colors are given: 923 O/BK (fluid temp sensor), 480 P/Y (TCC solenoid), 315 P/O (shift solenoid #2), 925 W/Y (EPC), and 237 O/Y (shift solenoid #1), ending at PCM pins 49, 53, 52, ~38, and 51. Circuit 395 GY/O runs from PCM pin 56 via C185 to the ignition system (page 21-2). Explanatory callouts describe each component's function: the PCM uses the fluid temperature thermistor for shift schedule, converter engagement, and EPC pressure adjustments; the TCC solenoid controls apply/release pressure to the converter clutch valve; the shift solenoids select gears 1–4; and the EPC is a variable-force solenoid regulating line pressure.

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Frequently asked questions

What wire color is the EPC solenoid circuit on the 4R70W transmission?: The Electronic Pressure Control (EPC) solenoid uses circuit 925 with a W/Y (white/yellow) wire, passing through connector C110 to the PCM.
What circuit and wire color do the 4R70W shift solenoids use?: Shift Solenoid #1 uses circuit 237, O/Y wire (PCM pin 51); Shift Solenoid #2 uses circuit 315, P/O wire (PCM pin 52). The shift solenoids provide gear selection of first through fourth by controlling pressure to the shift valves.
What does the transmission fluid temperature sensor do according to this diagram?: The PCM monitors the voltage drop across a temperature-sensitive thermistor to determine transmission fluid temperature, used to adjust shift schedules and torque converter engagement when fluid is cold, and to adjust EPC pressure for temperature. It's on circuit 923, O/BK wire, to PCM pin 49.
What is the function of the torque converter clutch solenoid?: It controls the apply and release pressure to the torque converter clutch control valve. It's wired on circuit 480, P/Y wire, to PCM pin 53.
Which connectors are in the 4R70W transmission wiring harness?: The diagram shows connector C1049 at the transmission, plus in-line connectors C103, C110, and C185 between the transmission and the PCM.