Fault Diagnosis, General

CAUTION: Never remove the control module's signal ground without first disconnecting the battery, as this could seriously damage the control module.

NOTE: When you have finished checking the functions, always clear the fault memory with the "CLEAR FAULT CODES" command. All systems can be cleared with the "CLEAR ALL" command.

1. SDA Mk II should always be connected to an ISAT.
2. The data link connector is located under the dashboard adjacent to the steering column.
3. During diagnosis the ignition switch should always be in the Drive position.
4. Obtain readouts and make a note of the stored diagnostic trouble codes in all systems before disconnecting the battery and any control modules.
5. If communication cannot be established between the ISAT and the control module, first check that the fuses are intact and that they are supplied with current. Then check the leads between the control module and the data link connector.
6. Also check that power and the correct ground are present at the data link connector and that the connector pins are undamaged and securely located.
7. To avoid damage to the control module and/or components, always check that the ignition is switched off before unplugging the connector(s).
8. Check that the control module's ground connections and supply voltages are correct.
9. It may sometimes be necessary to unplug connectors to check that the wiring and pins are undamaged and securely located. Refit connectors and clear all diagnostic trouble codes. If possible, start and drive the car to check whether the fault or faults persist.
10. Since all signals around the 12 V level are proportional to battery voltage the levels should be used as guidance only.
11. The 0 V signals indicate ground or 0 V level. On a sensitive multimeter a grounding point could give a voltage reading and a 0 V level (output signal) could be around 1 V without a fault existing. Accordingly, the level should be taken as guidance only.
12. Never switch from one unit to another (e.g. from V via A to ohms) on the meter without first having unplugged the instrument's test leads.