Scan Tool Unable To Contact Control Module

ISAT SCAN TOOL INPUT AND OUTPUT SIGNALS





Symptom Of Fault.
No contact with the Trionic control module via the ISAT scan tool.

Conditions.
ISAT scan tool communication with the Trionic system is OK in another car.





Diagnostic Procedure.
1. Check the data link connector's ground connection and power supply
- Take voltage readings in the data link connector across:

^ pin 16 and a good grounding point: B+
^ pin 16 and pin 4: B+
^ pin 16 and pin 5: B+

Are all readings OK?

YES: Continue with point 2.
NO: Check fuse 13. If necessary, repair or replace the lead concerned and continue with point 3.





2. Check the communications lead

- Turn the ignition switch to the ON position and then back to the OFF position.
- Take a voltage reading in the data link connector across:
pin 7 and a good grounding point, approx. = 6.5 V.

Is the voltage reading OK?

YES: Continue with point 3.
NO: Repair or replace the wiring between pin 7 of the data link connector and pin 33 of the Trionic control module if there is an open circuit or short circuit in it. Then continue with point 3.





3. Final check:

- Ignition switch in the ON position.
- Connect an ISAT scan tool.
- Contact the Trionic system.

The ISAT scan tool should show the Trionic menu.

Is contact established?

YES: The remedial measure taken was correct.
NO: Continue at "Before Replacing a Control Module". Component Tests and General Diagnostics