ISAT scan tool communicationfaulty

Symptom: No ISAT scan tool communication.

ISAT scan tool communication faulty

Fault symptom

No ISAT scan tool communication.

Condition

•	The control module has no power supply (+15 circuit).

•	The control module has no connection to ground.

•	No continuity in the data link connector (H16-1) circuit.

Diagnostic procedure

1 Check the control module's power supply and connection to ground

-	Unplug the control module's 4-pin connector. Ignition switch in the ON position. Take voltage readings on the control module's connector. Connect the voltmeter,

•

to battery positive (B+) and pin 1 = <0.5 V

•

to battery positive (B+) and pin 2 = <0.5 V

•

to pin 3 and battery negative (B-) = <0.1 V

Are all voltage readings OK?

yes

Continue with point 2.

no

Check the wiring harness, including connectors, and grounding point G30. Repair or replace as necessary.

2 Check the ISAT scan tool connector

-	Plug in the ISAT scan tool. The ISAT scan tool"s display should light up.

Is the ISAT scan tool"s display alight?

yes

Continue with point 5.

no

Continue with point 3.

3 Check the data link connector's power supply (+30 circuit)

-	Connect the test lamp to pin 16 of the data link connector and a good grounding point. The test lamp should light up.

Does the test lamp light up?

yes

Continue with point 4.

no

Check fuse 13 and change it if necessary. If the fuse is intact, check and if necessary rectify:

1) the lead between fuse 13 and pin 16 of the data link connector,

2) the supply of current up to fuse 13, as described in Service Manual 3:2 Electrical system, wiring diagram, power supply.

4 Check the data link connector's connection to ground

-	Connect the test lamp to data link connector

•

pins 4 and 16

•

pins 5 and 16 The test lamp should light up in both cases.

Does the test lamp light up?

yes

Continue with point 5.

no

Check and if necessary repair or replace the lead

•	between pin 4 and grounding point G33P

•	between pin 5 and grounding point G33S.

5 Check ISAT scan tool communication

-	Fit the control module. Select ABS ”M94/95” The ISAT scan tool should display the system menu for the ABS.

Does the ISAT scan tool display the system menu?

yes

The fault is of an intermittent nature.

no

Continue with point 6.

6 Check ISAT scan tool communication with another system

-	Select another system included in the car's equipment. The ISAT scan tool should display the selected system's menu.

Does the ISAT display the selected system's menu?

yes

Continue with point 7.

no

Check the ISAT scan tool, see Service Manual 1:5 Diagnosis and fault- tracing.

7 Check the wiring

-	Check the lead for continuity between pin 11 (25-pin connector) of the control module and pin 8 of the data link connector.

Is the lead OK?

yes

Continue with point 8.

no

Rectify the fault.

8 Final check

-	Using the ISAT scan tool, call up ABS M94/95.

Does ABS M94/95 answer?

yes

The diagnostic procedure carried out was correct.

no

Continue with