Yellow & Red Lights On Steady Or Intermittent
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 1988 Ford Pickup, 1988 Ford Cab & Chassis, 1988 Ford Bronco II, 1988 Ford Bronco, and 1987 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- Check brake fluid level. Fill if necessary. If brake fluid is okay and lights are still on, ensure parking brake is not on. On models equipped with diesel engine, build vacuum up. If both lights goes off, replace isolator diode in wiring harness. Isolator diode is located in engine compartment by the left fender apron in the fluid level indicator wiring on master cylinder.
- Voltage at fluid level sensor should be 11-13 volts. If both lights are still on, temporarily ground diagnostic lead. If code 4 flashes, go to CODE 4 in this article. If any other code was flashed, replace computer module. If both lights stayed on, unplug connector from master cylinder switch. Connect a jumper wire between 2 Purple and White wires on connector.
- Turn ignition on. If both lights go off, check master cylinder switch connector. If okay, replace switch. If both lights stayed on, unplug computer module connector. Turn ignition on. If both lights go out, replace computer module. If Yellow light goes off and Red light stays on, check for short in brake warning light circuit. If okay, check ignition switch.