ISAT Scan Tool Communication

CHECKING ISAT COMMUNICATION

Fault Symptom.
Not possible to establish communication between ISAT and TCM.

Diagnostic Procedure.
1. Connect ISAT scan tool to the car's data link connector.

If the ISAT display lights up, the voltage and ground connections are correct. Go to step 2.

If the ISAT display remains dark, check the voltage and the ground connections to diagnosis connector H16-1 and remedy any faults.

Connect a voltmeter as follows:
^ BATT+ -- H16-1 pin 16 <0.5 V.
^ H16-1 pin 5 -- BATT- <0.1 V.

If there is no BATT+ on pin 16, first check fuse 13.

2. With the ignition switched OFF, connect a BOB between the Transmission Control Module (TCM) and the wiring. Check the TCM feeder voltages and ground connections and remedy any faults. Connect a voltmeter as follows with the ignition in drive position:
^ BATT+ -- pin 17 <0.5 V,
^ BATT+ -- pin 18 <0.5 V,
^ pin 22 -- BATT- <0.1 V,
^ pin 35 -- BATT- <0.1 V.

3. Carry out continuity measuring of the wiring between diagnosis connector H16-1 pin 7 and TCM pin 23. Nominal resistance is <1 ohm.





4. With a BOB and ISAT connected, address the transmission with ISAT and measure with a voltmeter between pins 23 and 35. Nominal voltage is about 10 V. During the addressing the voltage falls to <0.5 V pulsed.

If the measurement results are correct, go to "Actions Before Changing a TCM".

If the measurement results are wrong, try to establish contact with any other system. If ISAT remains silent, ISAT should be checked for any faults.