Description of On-Board Diagnostics

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When all tests have been conducted as described in the action program for the particular diagnostic trouble code and no fault has been found, it is natural to assume that the control module is faulty.

Considering that the control module is both a very high quality and a very expensive component, it is important to be as sure as possible of the diagnosis.

Run through the following points very carefully before definitely deciding that the control module is the cause of the fault.

1. Check one more time that the points in the fault diagnosis schedule for the appropriate code have been followed.
If fault diagnosis has not been conducted according to the method for intermittent faults, repeat fault diagnosis and try to provoke intermittent faults.
2. Study the wiring diagram for the circuit in question and make sure that you understand it. If necessary, refer to the appropriate parts in the technical description and the electrical function description in "Wiring Diagrams".
3. Check all grounding points. If you have done this before, do it again.
4. Check the voltage feed and fuses to the control module.
5. Make sure that there are no bad connections in the control module connector.
6. If the original fault still persists, the control module will have to be changed.

NOTE: If the original fault is of an intermittent type, the fault is almost always in the cable assembly. For this reason, if the fault is intermittent, the cable assembly should be changed before the SRS control module is changed.