Using the ISAT
Fault diagnosis using an ISATDiagnosis
Observe the following:
- Never unplug the connector from the control module or disconnect any of the battery cables before the contents of the control module memory have been transferred to the ISAT.
- The 10-pin diagnostics socket is located under the rear seat on the RH side. It is protected by a plastic cover.
- Turn the ignition switch to the Drive position.
- The LH system has been assigned system No.1 in the ISAT.
- If communication between the ISAT and the control module cannot be established, first check the wiring between pins 12 and 16 of the control module and the diagnostics socket (347).
Also check that power and ground are present at the diagnostics socket and that the pins of the connector are undamaged.
- When the contents of the system's fault memory have been transferred and stored in the ISAT, the actual diagnosis has been completed. The faults are now available in the form of five-digit codes, following which further fault diagnosis work can be continued as described in the "ISAT fault- diagnosis chart", page 100.
Test readings on the control module connector
Before starting any fault diagnosis work on the LH system, the contact strip in the control module connector must first be exposed. All test readings must subsequently be taken from the side where the leads are connected to the pins in the connector.
1 Remove the control module, located inside the car on the RH wheel arch.
2 Unplug the connector.
3 Remove the protective cover and rubber dust excluder.
4 Withdraw the rubber gasket and lift up the contact strip.
5 Plug in the connector.
Checking the wiring
The words "Check the wiring between xx and yy" are used frequently in the fault-diagnosis charts. Some- times the wiring may run through different types of connector and, by implication, these must also be checked for circuit continuity and shorting.
Also check by eye that leads and connectors, etc. are undamaged.
Be alert to the possibility of interference from components connected to, or adjacent to, the wiring concerned.
How are the results displayed on the ISAT?
When an ISAT is used to simulate signals or functions by means of command codes issued to the control module, the results are shown on the display as a combination of numbers and letters (alphanumeric code).
The result is displayed in the form of five characters.
Example 1:
To check the position of the throttle butterfly, we enter the command 201 on the SAT keypad.'With the engine idling, the five alphanumeric characters appearing on the ISAT's display should be 8B101. See also "ISAT control commands, LH 2.4 (M1990)".
Example 2:
Sometimes we want to check whether a signal is high or low. To check the DRIVE signal, we enter the command 203 on the ISAT keypad.' If the signal is not activated the display will show 8B000, signifying that the signal is low.
If the signal is activated the signal should be high and the ISAT"s display ought to show 8B103.
See also "ISAT control commands, LH 2.4 (M1990)".
The five characters in the combination of letters and numbers (alphanumeric code) show the result of the entered command.