The Scan tool diagnostics instrument cannot communicate with the control module.

The Scan tool diagnostics instrument cannot communicate with the control module.

Turn the ignition switch to the ON position and check that the "CHECK ACS" warning lamp lights up for 3 seconds. It may remain on continuously if a fault is stored in the control module.

Test results OK?

yes

Continue with point 2.

no

Check the control module's ground connection and power supply (+30 and +15 circuits). Then continue with point 4.

2 Check the data link connector's power supply and ground connections

Take voltage readings across:

•	pin 16 and a good grounding point. A reading that is roughly the same as B+ (battery positive) should be obtained.

•	pins 16 and 4. A reading that is roughly the same as B+ (battery positive) should be obtained.

•	pins 16 and 5. A reading that is roughly the same as B+ (battery positive) should be obtained.

All readings OK?

yes

Continue with point 3.

no

Check fuse 13. If necessary, repair or replace the lead concerned and continue with point 4.

3 Check the communications lead

Check the wiring between pin 8 of the data link connector (diagnostic socket) and pin 38 of the control module.

Is the lead OK?

yes

Continue with point 4.

no

Repair or replace the wiring in question and continue with point 4.

4 Final check

-	Turn the ignition switch to the ON position.

-	Connect the Scan tool diagnostics instrument.

-	Establish communication with the Sensonic system. The Scan tool diagnostics instrument should show the Sensonic menu.

Is contact established?

yes

The steps taken to rectify the fault were correct.

no

Continue as described in the section.