2 - Checking The Resistance Of The Control Area Network (CAN) Cables

Checking The Resistance Of The Control Area Network (CAN) Cables







- Disconnect the battery negative lead. The power to the network must be cut when taking resistance readings. The reading may otherwise be incorrect.

NOTE: Also read: Battery, disconnecting

- Connect the adapter wiring to the central electronic module (CEM).

HINT: Where a breakout box cannot be used, take readings from the rear of the affected connectors if possible. This prevents terminal pins and socket housings being damaged.

When Taking Readings On The Low Speed Network
- When taking readings on the low speed network, the adapter wiring should be connected to the central electronic module (CEM) and the readings taken from there. The readings can also be taken in the connector for the power seat module (PSM). The advantage of using the adapter wiring connected to the central electronic module (CEM) is that all control modules can be connected to the network when taking readings and there is access to both the high speed and the low speed networks.

This resistance reading only measures main arteries in the low speed network, not the junctions for the road traffic information module (RTI), accessory electronic module (AEM), power seat module (PSM), phone module (PHM), audio module (AUM), driver's door module (DDM) and passenger door module (PDM). See the Wiring diagrams for Data communication.

When Taking Readings On The High Speed Network
- When taking readings on the high speed network, the readings should be taken at the engine control module (ECM) using adapter wiring. The engine control module (ECM) must be connected. This resistance reading only takes readings from the main arteries in the high speed network. See the Wiring diagrams for Data communication.

Connect the ohmmeter to the terminals for CAN-L and CAN-H on the relevant network. Work the connectors and twist the cable harness. The resistance must be approximately 60 ohms. Permitted values are 55-65 ohms.

Other Information
- See Scan Tool Connecting
- See Checking Wiring and Terminals under Related Tests, Information and Procedures

Is the value OK?

YES: Refer to 3. Checking A Short-Circuit In CAN Cables. 3 - Checking A Short-Circuit In CAN Cables
NO: Refer to 8. Identifying Fault Causes In the CAN Network. 8 - Identifying Fault Causes In the CAN Network