What wire color is the brake light power circuit?

Circuit 810, red/light green (R/LG), from the stop lamp switch to the rear stop lamps; the switch is fed by circuit 10, light green/red (LG/R).

What ground circuit do the stop lamps use?

Circuit 57, black (BK), through splices S400, S401, and S402 to grounds G400 and G401.

How does the clutch switch affect the stop lamp circuit?

On manual transmission vehicles, a clutch switch (open with the clutch pedal depressed) is in the circuit between C209 connectors; automatics have a straight-through 810 R/LG connection.

What other systems receive the stop lamp signal?

Circuit 810 R/LG also feeds the speed control and the electronic engine control.

Which connectors are in the high mount stop lamp circuit for the 3-door body?

C207, C403, C408, and C410 on circuit 810 R/LG, then ground on 57 BK through C410 and S402 to G401.

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1990 Ford Mustang Stop Lamp Wiring Diagram - Brake Light Circuit 810 R/LG

Wiring diagram of stop lamp and rear park/stop lamp circuits with wire codes and connectors

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Wiring diagram showing stop-lamp switch, speed/engine control, and rear park/stop lamp circuits with color codes, connectors, and grounds.

AI caption January 2007 · Photo 81 of 156

This document is a stop lamp (brake light) wiring schematic covering three body styles: convertible, 2-door, and 3-door. Power enters on circuit 10 (light green/red) to the stop lamp switch, which closes when the brake pedal is depressed, and exits on circuit 810 (red/light green). For automatic transmissions the circuit passes straight through connector C209; for manual transmissions it routes through a clutch switch that opens when the clutch pedal is depressed. Circuit 810 also feeds the speed control and electronic engine control systems. Downstream of connector C207, circuit 810 R/LG feeds the high mount stop lamp and the left and right rear park/stop lamps for each body style, passing through connectors C403, C408, and C410 depending on configuration. All lamps ground through circuit 57 (black) via splices S400, S401, and S402 to grounds G400 and G401 (a 'SEE GROUNDS' note appears for each branch). The diagram distinguishes the high mount stop lamp routing for 2-door versus 3-door versus convertible bodies. Readers can learn the wire circuit numbers, colors, connector locations in the circuit path, and switch logic for diagnosing brake light, cruise control cut-off, or clutch interlock issues.

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Frequently asked questions

What wire color is the brake light power circuit?: Circuit 810, red/light green (R/LG), from the stop lamp switch to the rear stop lamps; the switch is fed by circuit 10, light green/red (LG/R).
What ground circuit do the stop lamps use?: Circuit 57, black (BK), through splices S400, S401, and S402 to grounds G400 and G401.
How does the clutch switch affect the stop lamp circuit?: On manual transmission vehicles, a clutch switch (open with the clutch pedal depressed) is in the circuit between C209 connectors; automatics have a straight-through 810 R/LG connection.
What other systems receive the stop lamp signal?: Circuit 810 R/LG also feeds the speed control and the electronic engine control.
Which connectors are in the high mount stop lamp circuit for the 3-door body?: C207, C403, C408, and C410 on circuit 810 R/LG, then ground on 57 BK through C410 and S402 to G401.