Troubleshooting Hints

1. CHECK condition of GAUGES Fuse 4 and RADIO-I Fuse 17 (non-base). If any Fuse is open, LOCATE and REPAIR cause of overload and REPLACE fuse(s).
2. CHECK that Grounds G103, G112 (non-base) and G201 are clean and tight.
3. CHECK the BRAKE Indicator bulb for an open filament.
4. CHECK that the Parking Brake is fully released.
5. Ensure that there is adequate brake fluid in the reservoir.
6. If the BRAKE Indicator does not light for either the Brake Pressure Differential Switch or the Electronic Brake Control Module, then Diode D101 may have opened.
7. If the optional audible P/B Booster Fluid Flow Alarm (School Bus only) is present whenever the Ignition Switch is START or whenever the parking brake is engaged with the Ignition Switch in RUN, but there is no fluid flow or pressure problem, then In-Line Diode D202 has shorted. REPLACE In-Line Diode D202.
8. If the Brake Indicator Lamp lights and the P/B Booster Fluid Flow Alarm sounds immediately whenever the brake is applied and the conditions clear in a very short period of time, then REPLACE the P/B Booster Fluid Flow and Pressure Alarm Delay Module.
9. If the P/B Booster Fluid Flow Alarm sounds whenever there is a low pressure condition even though fluid flow is not low, then REPLACE the P/B Booster Fluid Flow Switch.
10. CHECK the Park Brake Warning Switch for proper installation and contacting the lever with the Park Brake off.
^ CHECK for a broken (or partially broken) wire inside the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded and if possible, should be checked by monitoring for a voltage drop with the system operational (under load).
^ CHECK for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to "General Troubleshooting Procedures,"). Diagnostic Aids