View Full Version : abs and brake lights come on?????????

10-05-2002, 03:50 PM
i have a 91 sc 5 speed drives fine the only thing is that when i brake my abs light and brake light both come on ....on the dash what could be the cause this please let me know

10-05-2002, 11:13 PM
If they go off after coming on, the likely cause is a worn out ABS accumulator. Do this test:

Driveway testing the operation of your HCU (Hydraulic control Unit):

1. Your HCU consists of a hydraulic pump, brake fluid reservoir, accumulator, solenoid valve body, pressure switch, and main body valve.
2. To driveway test the unit, turn key on/run (not just acc), engine off.
3. Listen for the pump charging the accumulator. Its a faint whine followed by a clunk over on the passenger side firewall. This should last for no more than a minute and the anti-lock and brake lights should both go out.
4. Depress the brake pedal numerous times, and count the number of presses you get before the pump motor starts again. 2 or less is a sign of a problem, especially if the anti-lock/brake lights come on and go off momentarily.
5. If you don't hear the sounds, you could have a bad set of relays, a bad pump motor, or pressure switch. If your pedal press count is low, its likely the accumulator.