TRAC System Does Not Operate

CAUTION: If ECU replacement is instructed in following testing, always ensure ECU connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECU malfunction.

Ensure no DTCs are present. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Inspect IG power supply circuit. See DTC 41: IG POWER SOURCE CIRCUIT in appropriate ANTI-LOCK BRAKES article. Inspect hydraulic lines for leakage. Repair as needed. Inspect speed sensor circuit(s). See DTC 31 , 32, 33 OR 34: SPEED SENSOR CIRCUIT in appropriate ANTI-LOCK article. On GS300, check Park/Neutral position switch circuit. See DTC P1780: PARK/NEUTRAL POSITION SWITCH MALFUNCTION article in AUTOMATIC TRANSMISSION. If all preceding tests are okay, replace ABS/TRAC ECU and TRAC ECU.