Flow of Diagnosis

Flow Chart:

Perform troubleshooting in accordance with the procedure on the chart.
[1] Customer Problem Analysis
Using the customer problem analysis check sheet for reference, ask the customer in as much detail as possible about the problem.
[2] Check And Clear The Diagnostic Trouble Codes (precheck)
If the ABS warning light lights up, and the ABS does not operate, the ECU stores diagnostic trouble codes corresponding to the problem in memory. Before confirming the trouble, first check the diagnostic trouble codes to see if there are any malfunction codes stored in memory. When there are malfunction codes, make a note of them, then clear them and proceed to "[3] Problem Symptom Confirmation".
[3] Problem Symptom Confirmation
Confirm the problem symptoms.
[4] Symptom Simulation
If the problem does not recur, simulate the problem by initially checking the circuits indicated by the diagnostic trouble code in step [2], using "Problem simulation method".
[5] Diagnostic Trouble Code Check
Check the diagnostic trouble codes. If a malfunction code is output, proceed to "[6] Diagnostic Trouble Code Chart". If the normal code is output, proceed to "[7] Problem Symptoms Chart". Be sure to proceed to "[6] Diagnostic Trouble Code Chart" after steps [2] and [3] are completed.If troubleshooting is attempted only by following the malfunction code stored in the memory, errors could be made in the diagnosis.
[6] Diagnostic Trouble Code Chart
If a malfunction code is confirmed in the diagnostic trouble code check, proceed to the inspection procedure indicated by the matrix chart for each diagnostic trouble code.
[7] Problem Symptoms Chart
If the normal code is confirmed in the diagnostic trouble code check, perform inspection in accordance with the inspection order in the problem symptoms chart.
[8] Circuit Inspection
Proceed with diagnosis of each circuit in accordance with the inspection order confirmed in [6] and [7]. Determine whether the cause of the problem is in the sensor, actuators, wire harness and connectors, or the ECU.
[9] Sensor Check
Use the ABS warning light to check if each of the signals from the speed sensors are being input correctly to the ECU. Instructions for this check are given in the circuit inspection.
[10] Repairs
After the cause of the problem is located, perform repairs by following the inspection and replacement procedures in this manual.
[11] Confirmation Test
After completing repairs, confirm not only that the malfunction is eliminated, but also conduct a test drive to make sure the entire ABS system is operating correctly.

NOTE: Steps [2], [5], [9], [11]: Diagnostic steps permitting the use of the TOYOTA hand-held