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

GENERAL INFORMATION

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 (2005-2012)»(ref-476703-S07259186972012060500000)

1. Continue Refer to «TAKING READING ON CABLE IN THE CAN NETWORK (HS-CAN)»(ref-476787-S15776863262012060500000)

Scheme 436

1. Disconnect the battery negative lead.
2. Remove the central electronic module (CEM)
3. Connect the breakout box to the cable harness for the central electronic module (CEM). Do not connect 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. Disconnect the CAN network to make it easier to locate a fault. A suitable point to disconnect the network is at the central electronic module (CEM). Fault-tracing therefore starts from the central electronic module (CEM). Take resistance readings across the following terminals. Various readings will be obtained due to the structure of the network. Twist the cable harness and work the connectors at accessible points along the cable harness in order to check whether the resistance changes during each measurement. This method can be used to detect intermittent short-circuits or open-circuits. NOTE: The following resistance readings only measure the main arteries in the high speed network, not the junctions that exist for some control modules. If an open-circuit is suspected in a cable, or a short-circuit is suspected in one of its junctions, the connector at the control module for this junction must be disconnected and the reading taken from there. Take the following readings Resistance between C3:47 and C3:48. Resistance should be 120 ohms. NOTE: Measuring will only give value 120 ohms if the main circuit in the CAN-net is intact. If there is a short-circuit somewhere in the CAN-net (either main circuit or other branching) the resistance will be 0 ohms. The resistance between C3:48 and a connection to voltage as well as between C3:48 and a short-circuit to ground. The resistance shall be very high (more than 1 Mohms). The resistance between C3:47 and a connection to voltage as well as between C3:47 and a short-circuit to ground. The resistance shall be very high (more than 1 Mohms). HINT: Any short-circuit detected on the CAN-net may be on the main circuit or on any branching running out to some control modules. If a fault is found, try to disconnect the junction with the fault at a point further forward. Try to locate the fault in this way. Remedy as necessary. Other information see «BATTERY, DISCONNECTING»(ref-476746-S00156360512012060500000) see «CONNECTING THE BREAKOUT BOX»(ref-476691-S30437390172012060500000) see «SIGNAL SPECIFICATION»(/volvo/xc90/i-2002-2006/remont/engine-control-systems/#engine-control-signal-description-and-specification) see «CHECKING WIRING AND TERMINALS»(/volvo/xc90/i-2002-2006/remont/body-electrical/#wiring-and-terminals-general-diagnostics-and-tests)

Was a fault detected?

1. YES Refer to «VERIFICATION»(ref-476787-S07581085702012060500000)
2. NO Refer to «CHECKING THE TRAFFIC LOAD ON THE CAN CABLES»(ref-476787-S19355485352012060500000)

HINT: For general information about troubleshooting in the Control Area Network (CAN), see the linked document below.

Note. When selecting the vehicle profile, the correct vehicle must be identified. Use the "Retrieve VIN" button. Troubleshooting may fail if this is not done.

In order to check the CAN cables, the resistance of the network must be measured. The resistance between the two high-speed CAN cables, with the network connected, must be 60 ohms. The acceptable range of this reading is approx. 55-65 ohms.

If the communication diagnostic trouble code can be read from the control module, the malfunction is probably intermittent.

An intermittent malfunction in the power supply to a control module is indicated by individual diagnostic trouble codes in the Central Electronic Module (CEM) (CEM-1A5X or CEM-1A6X, as appropriate). There is probably no diagnostic trouble code in the control module that the central electronic module (CEM) has generated, since the module cannot generate a diagnostic trouble code when it is not supplied with voltage.

Other information

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

1. Continue Refer to «MEASURING CABLES IN CAN-NETWORK (HS-CAN)»(ref-476787-S03189870722012060500000)

The diagnostic trouble code (DTC) is stored when the communication between the central electronic module (CEM) and the relevant control module has been interrupted. There can be a number of causes for interruptions in the communication

1. Faulty signal configuration in the control module that stored the diagnostic trouble code (DTC). The fault can be due to a customer or workshop replacing a control module without downloading new software for the replacement
2. Intermittent open-circuit in one or both CAN cables in part of the network
3. Intermittent short-circuits between the CAN cables
4. Intermittent short-circuits between one of the CAN cables and ground or supply voltage
5. Internal fault in the control module that stored the diagnostic trouble code (DTC).

The fault can also be due to faulty software in a control module, a hardware problem in the CAN network (faulty cables) or a fault in a control module.

Note. If there is a diagnostic trouble code (DTC) for a communication fault in a control module, check whether diagnostic trouble codes (DTCs) have been stored in the central electronic module (CEM). The central electronic module (CEM) monitors the voltage level in the CAN cables and 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.

Corrective actions

1. If this diagnostic trouble code (DTC) is the only communication diagnostic trouble code (DTC) stored in one of the control modules in the high speed network, try to remedy the fault by downloading new software for the control module that stored the diagnostic trouble code (DTC)
2. Check the cables in the CAN network according to the following fault-tracing
3. The control module should be replaced as a last resort.

Other information

1. see «GENERAL INFORMATION ABOUT FAULT-TRACING IN THE CAN NETWORK»(ref-494734-S01796838862012081600000)
2. Go to the tab software and program the control module with the latest software.

1. Continue Refer to «VERIFICATION»(ref-476787-S06671249202012060500000)

See also:
• SIGNAL SPECIFICATION, ENGINE CONTROL MODULE (ECM)
• CONTENTS
• SIGNAL SPECIFICATION
• CHECKING WIRING AND TERMINALS
• OIL LEVEL SENSOR, REPLACING