Pinpoint Test J: The Generic Electronic Module (GEM) Does Not Respond To The Scan Tool

Communications Network

Pinpoint Test J: The Generic Electronic Module (GEM) Does Not Respond To The Scan Tool

Refer to Wiring Diagram Set 13, Power Distribution for schematic and connector information. Diagrams By Number

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

Normal Operation

The Generic Electronic Module (GEM) communicates with the scan tool through the Medium Speed Controller Area Network (MS-CAN).

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- GEM


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

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

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.

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J1 CHECK THE GEM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Generic Electronic Module (GEM) C201a.
- Ignition ON.
- Measure the voltage between the GEM C201a-10, circuit 15-DK20 (GN/OG), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to J2.

No
VERIFY the Central Junction Box (CJB) fuse 179 (7.5A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool. Diagrams By Number

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J2 CHECK THE GEM GROUND CIRCUIT FOR AN OPEN


- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: GEM C201d.
- Measure the resistance between the GEM C201d-2, circuit 91-DK20 (BK/RD), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to J3.

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

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J3 CHECK THE MS-CAN CIRCUITS BETWEEN THE GEM AND THE DLC FOR AN OPEN


- Disconnect: GEM C201b.
- Measure the resistance between the GEM C201b-23, circuit 4-EC14 (GY/OG), harness side and the DLC C251-3, circuit 4-EC1 (GY/RD)/4-EC13 (GY/VT)/4-EC14 (GY/OG), harness side.




- Measure the resistance between the GEM C201b-22, circuit 5-EC14 (BU/BK), harness side and the DLC C251-11, circuit 5-EC1 (BU/RD)/5-EC13 (BU/WH)/5-EC14 (BU/BK), harness side.




- Are the resistances 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 GEM OPERATION


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

Yes
INSTALL a new GEM. REFER to Multifunction Electronic Modules Service and Repair. 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.

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