Brake System Warning Indicator

If brake system warning indicator remains off, check for blown fuse. If indicator remains on with ignition switch in RUN position and parking brake off, check for defective parking brake switch or leak in brake hydraulic system.
Verify leakage by removing electrical connector from brake pressure switch. If indicator turns off, brake pressure switch is closed (low pressure in one system). Repair as necessary. If indicator remains illuminated, check for short in parking brake switch, ignition switch or wiring.
If indicator illuminates when ignition switch is in START position, but not when parking brake is applied, measure voltage at parking brake switch Tan/White wire (with ignition switch in RUN position and parking brake applied).
If battery voltage exists at Tan/White wire, replace parking brake switch. If no voltage exists at Tan/White wire, check for open in wire between switch and bulkhead connector on firewall.
If indicator illuminates with parking brake applied, but not when ignition switch is in START position, check for voltage at ignition switch START terminal. If battery voltage exists, replace ignition switch. If battery voltage is not present, check for open in Tan/White wire between ignition switch and bulkhead connector.
If indicator does not illuminate with low brake accumulator pressure, check for battery voltage at Tan/White wire of brake accumulator pressure switch. If voltage is not present, replace switch.