Self-Diagnostic System
ABS control unit performs 2 self-diagnostic functions. Initial diagnosis is performed from the time engine starts until ABS/TCS indicator lights go off. Regular diagnosis is continuously performed from time indicator lights go off on start-up until ignition is turned off. When a problem is detected, ABS/TCS control unit will turn ABS indicator lights on, go into fail-safe mode and stop either ABS/TCS control, and memorizes DTC.
When ABS modulator/control unit detects a problem and either indicator light comes on, ABS modulator/control unit will store a DTC. ABS modulator/control unit can store any number of DTCs. The DTCs are indicated in order of ascending number. DTCs are memorized in EEPROM (non-volatile memory) and cannot be erased from memory by disconnecting battery. See CLEARING DIAGNOSTIC TROUBLE CODES under DIAGNOSIS & TESTING. When 2 or more DTCs are stored in ABS modulator/control unit, trouble shoot DTCs in order of appearance. If complaint cannot be verified, establish conditions present when indicator light came on. If possible, test drive vehicle under similar conditions. If neither indicator light comes on during test drive, check for loose connectors and/or terminals. Shake wiring and connectors while diagnosing. Attempting to follow diagnostic test procedures when indicator is not lit may lead to faulty diagnosis. See, Fig 1 and Fig 2 for ABS & TCS Self-diagnostic Tables. See, Fig 3 and Fig 4 for ABS & TCS Operation Mode Tables.