LH System Diagnostics

Diagnostic methods

Fault diagnosis can be carried out in different ways. One and the same system can be analyzed by using one or more diagnostic methods.

- ISAT scan tool (Model Year 1988-1993)

- Lamp-flash codes (Model Year 1988-1993)

- LH tester

To facilitate taking instrument readings, the test points on the different systems can be "broken out" by means of a Breakout Box (BOB). In such case, the Breakout Box is connected to the system's control module.

In connection with fault diagnosis
The words "Check the wiring from ... to are used frequently in the fault diagnosis procedure described in the section for the respective system.

In certain cases the wiring includes connectors or distribution points and it is then understood that these should also be checked for continuity shorting.

Be alert to the possibility of interference from components that are connected to the wiring concerned. Also check that the leads are not damaged or causing defective grounding. Always make absolutely sure that you are using the correct wiring diagram for the car, model year and type of system.