Engine Control Module (ECM) Diagnostic Trouble Codes - 8 of 13: Overview Volvo XC90 I

GENERAL INFORMATION

In order to check the control area network (CAN) cables, the resistance in the network must be measured. The resistance between the two controller area network (CAN) wiring, with the network connected 60 ohms. The resistance can differ depending on the configuration of the car. Permitted values are 55-65 ohms. This applies to both the high speed side network and the low speed side network.

HINT: Take a copy of the data communication side for each model. Note which diagnostic trouble codes (DTCs) are stored in each control module. This facilitates fault-tracing considerably.

Check if the diagnostic trouble codes (DTCs) for failed communication are stored in the central electronic module (CEM). If this is the case, first fault-trace according to these diagnostic trouble codes (DTCs).

Other information

1. For general information about fault-tracing the control area network (CAN), see «GENERAL INFORMATION ABOUT FAULT-TRACING IN THE CAN NETWORK (2005-2012)»(ref-476703-S07259186972012060500000)

1. Continue Refer to «CHECKING THE RESISTANCE OF THE CONTROL AREA NETWORK (CAN) CABLES»(ref-476773-S30794424482012060500000)

Scheme 264

Scheme 265

1. 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»(ref-476746-S00156360512012060500000)
2. 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). 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. 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 «CONNECTING THE BREAKOUT BOX»(ref-476703-S35775802292012060500000) see «CHECKING WIRING AND TERMINALS»(/volvo/xc90/i-2002-2006/remont/body-electrical/#wiring-and-terminals-general-diagnostics-and-tests)

Is the value OK?

1. YES Refer to «CHECKING A SHORT-CIRCUIT IN CAN CABLES»(ref-476773-S00731537802012060500000)
2. NO Refer to «IDENTIFYING FAULT CAUSES IN THE CAN NETWORK»(ref-476773-S08650018612012060500000)

The diagnostic trouble code (DTC) is stored in the event of communication faults on the high speed side of the control area network (CAN). There can be a number of causes for faults in the communication

1. Intermittent open-circuit in one or both CAN cables in part of the network
2. Intermittent short-circuits between the CAN cables
3. Intermittent short-circuits between one of the CAN cables and ground or supply voltage
4. Fault in the communication circuit in one or more control modules
5. Internal fault in a control module on the CAN network that results in the control module transmitting faulty messages on the CAN network.

In the event of a diagnostic trouble code (DTC) for a communication fault in the relevant control module, any diagnostic trouble codes (DTCs) in the central electronic module (CEM) must also be checked. The central electronic module (CEM) monitors the voltage level in the CAN cables. The central electronic module (CEM) is the only control module that can directly store a diagnostic trouble code (DTC) for a short-circuit in one of the cables for ground or supply voltage. Do not replace the central electronic module (CEM) in the event of a CAN fault unless fault-tracing has indicated that the central electronic module (CEM) has an internal fault.

In order to check the control area network (CAN) cables, the resistance in the network must be measured.

Other information

1. see «GENERAL INFORMATION ABOUT FAULT-TRACING IN THE CAN NETWORK»(ref-494734-S01796838862012081600000)

1. Continue Refer to «TAKING READING ON CABLE IN THE CAN NETWORK (HS-CAN)»(ref-476773-S38808333982012060500000)

See also:
• CHECKING WIRING AND TERMINALS
• SIGNAL DESCRIPTION
• ACCELERATOR PEDAL (AP), REPLACING
• CHECKING WIRING AND TERMINALS
• COMPONENT SPECIFICATIONS
• SIGNAL SPECIFICATION, ENGINE CONTROL MODULE (ECM)