Inspection Procedure 1

INSPECTION PROCEDURE 1: Communication between the Scan Tool and all the Systems is Not Possible.






CIRCUIT OPERATION
A battery positive voltage is applied on the data link connector power terminal (terminal 16). The ground terminals (terminal 4, 5) are grounded to the vehicle body.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a defect in power supply circuit or the ground circuit.

TROUBLESHOOTING HINTS
The most likely causes for this case are:
^ Malfunction of the data link connector
^ Damaged wiring harness or connector

DIAGNOSIS
Required Special Tool:
^ MB991223: Harness Set

STEP 1. Check the power supply circuit. Measure the voltage at data link connector C-14.





Measure the voltage between terminal 16 and ground. It should measure approximately 12 volts (battery positive voltage).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 4.
NO: Go to Step 2.

STEP 2. Check the following connectors.





^ Data link connector C-14





^ Junction block connectors C-212, C-214





^ Intermediate connector C-126
Check the connectors for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?
YES: Go to Step 3.
NO: Repair it and then go to Step 7.

STEP 3. Check the following harness wire.








The wire between data link connector C-14 (terminal 16) and junction block connector C-212 (terminal 1)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 7.
NO: Go to Step 7.

STEP 4. Check the ground circuit. Measure the resistance at data link connector C-14.





Measure the resistance between terminal 4 and ground, and terminal 5 and ground. It should measure less than 2 ohms.
Q: Is the resistance 2 ohms or less?
YES: Replace the scan tool and then go to Step 7.
NO: Go to Step 5.

STEP 5. Check the following connector.





^ Data link connector C-14
Check the connector, for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connector and terminals in good condition?
YES: Go to Step 6.
NO: Repair it and then go to Step 7.

STEP 6. Check the following harness wires.








^ The wire between data link connector C-14 (terminal 4) and ground (No.7)
^ The wire between data link connector C-14 (terminal 5) and ground (No.7)
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 7.
NO: Go to Step 7.

STEP 7. Retest the system.
Q: Does the scan tool communicate with the whole system?
YES: The procedure is complete.
NO: Return to Step 1.