Initial Inspection and Diagnostic Overview

Fig. 25 Engine Warning Light In Dash:

The engine control unit has a special fault memory for self diagnosis. This memory constantly monitors the operation of the engine control system, and automatically stores any faults or defects. This information can be accessed by simply operating the throttle switches, and the brake light switch in the proper order (see 'EXTRACTING FAULT CODES' for procedure).
The information is then coded by tachometer needle position and the engine light in the instrument cluster, Fig. 25.
To perform the diagnosis procedure, a certain sequence must be followed. When the ignition is turned OFF, the fault memory is erased. After the engine is restarted, the monitoring process is started again. It is very important not to turn the ignition OFF when performing the diagnosis procedure. Before beginning the diagnosis, the car should be driven (on the road or a dynomometer) so that an engine speed greater then 3000 rpm, and a boost pressure of at least 1.2 bar (3 psi above atmospheric pressure) are reached. This is to ensure that all component operations are checked and stored in memory.
If the car has a no start condition, the engine must be cranked with the starter for at least 5 seconds. This will store the information on those components that could possibly cause a no start condition.