Chart A-15, Code 61 - Low Fluid Pressure
WARNING: This page does not describe the selected car, but rather 14 other vehicles, including the 1990 Pontiac Bonneville, 1990 Oldsmobile Ninety-Eight, 1990 Oldsmobile Eighty-Eight, 1990 Cadillac Fleetwood, and 1990 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
- The low fluid/low pressure warning loop circuit, sometimes called EBCM loop circuit, consists of continuous loop from EBCM pin No. 9 (reservoir warning input) to pin No. 10 (pressure warning input). This circuit runs through 2 normally closed switches. If EBCM finds the voltage at pin No. 10 below expected value, EBCM enters "inhibit" mode and partially disables anti-lock mode while turning on "ANTI-LOCK" lamp.
- When low hydraulic accumulator pressure is detected at the pressure switch on the hydraulic unit, the pressure switch opens and closes to maintain pressure between 1465 psi (10,103 kPa) and 1987 psi (13,703 kPa).
- Low brake fluid is detected through the EBCM and fluid level sensor in reservoir. This switch is normally closed. In case of low fluid level the switch opens the circuit between pins A and B.
- An open in any loop circuit wiring will be interpreted as a low fluid/low pressure warning. However, Code 61 is designed to set only if the signal through the warning loop is NOT readable. It will not set if low fluid/low pressure condition is detected. Shorted ABS diode and loop circuits shorting to voltage are primary causes of code 61 set.