On-Board Diagnostics

WARNING: Never remove the control module's signal ground without first disconnecting the battery, as the control module could otherwise be seriously damaged.

1 SDA MkII must always be connected to an ISAT Scan Tool.

2 The data link connector is located below the dashboard adjacent to the steering column.

3 Before fault diagnosis can be carried out the control module must first be alerted. If it has been inactive for more than three seconds it will assume the idle state. To establish communication between the ISAT scan tool and the control module, the control module must therefore first be "woken up". Programming and Relearning

4 Obtain readings of the diagnostic trouble codes for all systems and make a note of them before disconnecting the battery and any control modules.

5 If communication cannot be established between the ISAT scan tool and the control module, first check that the control module is "awake". Then check that the fuses are intact and live. Then check the leads between the control module and the data link connector.

6 Also check that the data link connector is supplied with power and connected to the correct ground, and that the pins of the connector are undamaged and properly located.

7 To avoid damaging the control module and/or other components, always make sure that the ignition is switched off before unplugging the connector or connectors.

8 Check that the control module's ground connections and supply voltages are correct.

9 It may sometimes be worthwhile unplugging connectors to check that their pins and sockets are undamaged and properly located. Plug in the connectors again and clear all diagnostic trouble codes. If possible, start the engine and/or drive the car to check whether the fault or faults still persist.

10 Since all signals round the 12v level are proportional to battery voltage, these levels should be used only as guidance.

11 Zero-voltage signals indicate ground or zero-voltage level. A grounding point can give a measurable voltage reading on a sensitive multimeter and a zero-voltage level (output signal) can give a reading of about 1v. Therefore the level should be used as guidance only.

12 Never switch from one unit of measurement to another (e.g.. from V via I to ohms) on a multimeter without first disconnecting the instrument's test leads.

Important: After checking all functions, always clear the fault memory with the "CLEAR FAULT CODES" command. All systems can be cleared with the "RESET ALL" command.