Pinpoint Test J: The Liftgate/Trunk Module (LTM) Does Not Respond to the Scan Tool

Communications Network

Pinpoint Tests

Pinpoint Test J: The Liftgate/Trunk Module (LTM) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number

Refer to Wiring Diagram Set 113, Luggage Compartment for schematic and connector information. Diagrams By Number

Normal Operation

The Liftgate/Trunk Module (LTM) communicates with the scan tool through the ISO 9141 communications network. Circuit 70 (LB/WH) provides the network connection to the LTM. Voltage for the LTM is provided by circuits 640 (RD/YE), 1190 (YE/BK) and 1524 (DB). Ground is provided by circuits 57 (BK) and 676 (PK/OG).

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- LTM



PINPOINT TEST J: THE LTM DOES NOT RESPOND TO THE SCAN TOOL

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery will result in false resistance readings. Refer to Battery.

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J1 CHECK THE LTM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect the scan tool cable from the Data Link Connector (DLC).
- Disconnect: LTM C4081c and C4081d.
- Ignition ON.
- Measure the voltage between the LTM C4081c-6, circuit 640 (RD/YE), harness side and ground; between the LTM C4081c-17, circuit 1524 (DB), harness side and ground; and between the LTM C4081d-4, circuit 1190 (YE/BK), harness side and ground.




- Are the voltages greater than 10 volts?

Yes
GO to J2.

No
VERIFY the Battery Junction Box (BJB) fuse 108 (40A), and Central Junction Box (CJB) fuses 8 (10A) and 19 (7.5A) are OK. If OK, REPAIR the circuit in question. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the short circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.

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J2 CHECK THE LTM GROUND CIRCUITS FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the LTM C4081c-12, circuit 676 (PK/OG), harness side and ground; and between the LTM C4081d-3, circuit 57 (BK), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to J3.

No
REPAIR the circuit in question. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

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J3 CHECK THE ISO 9141 CIRCUIT BETWEEN THE DLC AND THE LTM FOR AN OPEN


- Measure the resistance between the DLC C251-7, circuit 70 (LB/WH), harness side and the LTM C4081a-7, circuit 70 (LB/WH), harness side.




- Is the resistance less than 5 ohms?

Yes
CONNECT the negative battery cable. GO to J4.

No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.

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J4 CHECK FOR CORRECT LTM OPERATION


- Disconnect all the LTM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the LTM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new LTM. CLEAR the DTCs. REPEAT the network test with the scan tool.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.

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