Testing Precautions

If a 20s trouble code is stored in ECU, no other codes will be stored until all 20s codes have been serviced and cleared. ECU cannot store trouble codes with same first digit (25 and 26). Lowest number code (25) will be stored first. Codes must be serviced in order received and cleared before continuing. Drive vehicle at about 25 MPH and check for additional codes. Solenoid valve service codes will override all other codes stored. If no codes are stored, system has passed self-test. If codes appear, refer to ON-BOARD SELF-TEST TROUBLE CODE INDEX  under ON-BOARD SELF-TESTS. If BRAKE warning light is on or comes on intermittently, go to WARNING LIGHT SYMPTOM SEQUENCE CHART. See Figure .