Points to Remember When Diagnosing Faults

Points to remember when diagnosing faults

1 The data link connector (diagnostics socket). colored black, is situated under the right-hand front seat.

2 During diagnosis, the ignition switch should always be in the Drive position.

3 The SF1 system has SAT scan tool system number 10.

4 Retrieve and make a note of all fault codes stored in the ISAT scan tool before disconnecting the battery and the ECM.

5 If communication cannot be established between the SAT and the system, first check fuse 21 and then the leads between terminal 33 of the ECM and pin 1 of the data link connector. Also check that the data link connector is supplied with the correct current and ground and that the pins of the connectors are undamaged and firmly located.

6 Review "Diagnostic Trouble Codes" for a list of all diagnostic trouble codes (DTCs) for the SFI system.

7 Review "Command Codes" for a list of all command codes for the SFI system.

8 To avoid damaging ECMs and/or components, always make sure that the ignition and main relay are switched off before unplugging any connectors.

9 Always check that the ECM's ground connections and supply voltages are correct.

NOTE:
On completion of fault diagnosis, always erase the fault memory by means of command code 2000.

10 It may sometimes be well worth unplugging connectors to check that sockets and pins are undamaged and firmly located. Afterwards, plug in the connectors again and erase all DTCs. If possible, start the car or drive it to see whether the fault or faults persist.

11 Since all signals around the 12-volt level are proportional to battery positive voltage, the levels should be used as guidance only.

12 The 0 V signals denote ground but on a sensitive multimeter they may produce a measurable voltage reading.

13 Never switch from one unit of measurement to another (e.g. from volts, through amps to ohms) on the meter without first disconnecting the test leads.

Breakout-box
Always use one or more breakout boxes in conjunction with the 70-pin test cable when diagnosing faults in the SFI system's circuits and wiring.