ISAT (Scan Tool) Communication Faulty

Fault Symptom
The ISAT communication does not operate.

Condition
- The electronic control module lacks +15-voltage supply (connector pin 15).
- The electronic control module lacks a grounding connection (connector pin 19).
- Open-circuit in the electrical circuit to the diagnostic switch (H16-1).

Diagnostic Procedure
1. Electronic control module ground and voltage supply check
- Disconnect the electronic control module connector.
The ignition timing is in the On position.
Take a voltage measurement at the electronic control module sensor connector. Connect the voltmeter,
- Between B+ and pin 15 = less than 0.5V
- Between B+ and pin 17 = less than 0.5V
- Between B+ and pin 18 = less than 0.5V
- between pin 16 and B- = less than 0.1V
- between pin 19 and B- = less than 0.1V

Are the voltage ratings OK?
If YES Continue with point 2.
If NO Check and rectify the wiring including the connector and the grounding points.

2. ISAT switch check
- Connect the ISAT Scan Tool
The ISAT display should come on.

Does the ISAT display come on?
If YES Continue with point 5
If NO Continue with point 3.





3. Check of +30 voltage supply in diagnostic switch
- Connect the test lamp between pin 16 of the diagnostic switch and a definite grounding point
The test lamp should be on.

Does the test lamp come on?
If YES Continue with point 4.
If NO Inspect and possibly replace fuse 13.
Is the fuse intact, Check and correct
A. The cable between fuse 13 and pin 16 of the diagnostic switch.
B. The supply voltage to fuse 13.

4. inspection of the ground connection at the diagnostic switch
- Connect the test lamp Unseen the diagnostic switch
- Pin 4 and pin 16
- Pin 5 and pin 16
The test lamp should come on in troth measurements

Does the test lamp come on?
If YES Continue with point 5.
If NO Check and rectify the cable including the grounding point.
- Between pin 4 and grounding point G33P
- Between pin 5 and grounding point G33S.





5. ISAT communication check
- Install the electronic control module.
Select "ABS 5.3"
The ISAT Scan tool should display the system menu for ABS 5.3.

Does the ISAT display the system menu?
If YES The fault is of intermittent character.
If NO Continue with point 6.

6. Inspection of ISAT communication with and/or system
- Select another system that the car is equipped with.
The ISAT Scan Tool should display the system menu of the selected system.

Does the ISAT display the selected system menu?
If YES Continue with point 7.
If NO Check the ISAT Scan Tool per manufacturers instructions





7. Cable inspection
- Make a continuity test of conductors between pin 11 of the electronic control module and pin 8 of the diagnostic switch.

Is the cable OK?
If YES Continue with point 8.
If NO Rectify the fault

8. Final inspection
- Make an ISAT communication to ABS 5.3

Does the ABS 5.3 answer?
If YES The diagnostic procedure taken was correct
If NO, Continue with Preliminary Steps Prior To (ECM) Replacement Procedure.