What wire colors does the Ford F-Series rear axle speed sensor use?

The rear axle sensor uses circuit 523 R/PK (red/pink) and circuit 519 LG/BK (light green/black), connecting through connector C404.

How does the VSS signal reach the speedometer?

The rear axle sensor's AC signal goes to the Programmable Speedometer/Odometer Module (PSOM) in the instrument cluster (connector C252), which converts it to a standard 8,000 pulses-per-mile speed signal output sent to the PCM and Speed Control Servo/Amplifier Assembly on circuit 679 GY/BK.

What fuses power the PSOM in this diagram?

A 15A fuse (position 8, hot at all times) on circuit 54 LG/Y and a 10A fuse (position 18, hot in run) on circuit 296 W/P, from the fuse panel (pages 13-3, 13-9, 13-13).

Where does the PSOM ground?

Through circuit 901 R/LB via connectors C216 and C202 to splice S216, then circuit 570 BK/W to ground G200 (see grounds pages 10-9, 10-10).

Which connector goes to the PCM for the speed signal?

For gasoline engines, circuit 679 GY/BK goes to the PCM via connector C185 (pages 23-5, 24-2, 25-2, 26-4). For diesel with E4OD transmission, it goes via connector C1027 to the PCM (page 30-3).

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Ford F-Series Vehicle Speed Sensor (VSS) Wiring Diagram - PSOM, RABS, PCM

Vehicle Speed Sensor (VSS) wiring diagram, F-Series, page 64-1, rear axle sensor and PSOM circuits

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Ford F-Series VSS wiring diagram showing rear axle sensor, RABS module and programmable speedometer/odometer module (PSOM) circuits.

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This document is page 64-1 of a Ford wiring diagram set, showing the Vehicle Speed Sensor (VSS) circuit for F-Series trucks. It traces the rear axle sensor, which monitors rear axle speed by sensing exciter-ring teeth and produces an AC signal (circuits 523 R/PK and 519 LG/BK) that feeds the Rear Anti-Lock Brake (RABS) module at connector C277, the RABS data link connector C143, and the Programmable Speedometer/Odometer Module (PSOM) at connector C252 in the instrument cluster. The PSOM, powered by a 15A hot-at-all-times fuse (circuit 54 LG/Y) and a 10A hot-in-run fuse (circuit 296 W/P), converts the sensor input to a standard 8,000 pulses-per-mile speed signal (679 GY/BK) that is distributed to the Powertrain Control Module (via C185 for gasoline or C1027 for diesel with E4OD transmission) and to the Speed Control Servo/Amplifier Assembly (C216). Grounding runs through circuits 901 R/LB and 570 BK/W to G200. Cross-references point to fuse panel pages 13-3, 13-9, 13-13, power distribution pages 13-15/13-17, RABS page 42-2, PCM pages 23-5/24-2/25-2/26-4/30-3, speed control page 31-4, instrument cluster page 60-6, and grounds pages 10-9/10-10. A reader learns wire colors, connector numbers, splice points, and signal flow for diagnosing VSS/speedometer issues.

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Frequently asked questions

What wire colors does the Ford F-Series rear axle speed sensor use?: The rear axle sensor uses circuit 523 R/PK (red/pink) and circuit 519 LG/BK (light green/black), connecting through connector C404.
How does the VSS signal reach the speedometer?: The rear axle sensor's AC signal goes to the Programmable Speedometer/Odometer Module (PSOM) in the instrument cluster (connector C252), which converts it to a standard 8,000 pulses-per-mile speed signal output sent to the PCM and Speed Control Servo/Amplifier Assembly on circuit 679 GY/BK.
What fuses power the PSOM in this diagram?: A 15A fuse (position 8, hot at all times) on circuit 54 LG/Y and a 10A fuse (position 18, hot in run) on circuit 296 W/P, from the fuse panel (pages 13-3, 13-9, 13-13).
Where does the PSOM ground?: Through circuit 901 R/LB via connectors C216 and C202 to splice S216, then circuit 570 BK/W to ground G200 (see grounds pages 10-9, 10-10).
Which connector goes to the PCM for the speed signal?: For gasoline engines, circuit 679 GY/BK goes to the PCM via connector C185 (pages 23-5, 24-2, 25-2, 26-4). For diesel with E4OD transmission, it goes via connector C1027 to the PCM (page 30-3).