Headlamp Control Module (Hcm) Diagnostic Trouble Codes: Overview Volvo XC90 I

GENERAL INFORMATION

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-476788-S24880788392012060500000)

Scheme 2

1. Ignition off
2. Disconnect the minus terminal on the battery.
3. Connect a breakout box to the Engine Control Module (ECM). NOTE: Also connect the engine control module (ECM) to the adapter cable harness, otherwise the measured values will be incorrect. HINT: Use the Service Manual, Wiring Diagrams as help when measuring. Measure the resistance between the connections below. Due to the network design, different measurement values will be obtained. For each measurement, twist the cable harness and wiggle the connections, where accessible, to detect any intermittent short-circuits or open circuits. NOTE: The following resistance measurements only measure the main paths in the high-speed network, not the junctions that exist for some control modules. An open circuit in one path cannot be detected by this measurement. However, a short-circuit in a branch can be detected. Measure the resistance between #B58 (#C58) and #B45 (#C45). The resistance shall be approx. 60 ohms. Permitted values approx. 55-65 ohms. Also measure the resistance between each connection and the voltage as well as ground. The resistance must be infinite or very large (more than 1 Mohms). HINT: If a malfunction is detected, then try to separate the junction with the measured malfunction at an appropriate point further along the cable. Unplug any connector/control module nearest to the previous measurement point and measure again. In this manner, try to find the malfunction. Remedy the cables 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 «CONTENTS»(/volvo/xc90/i-2002-2006/remont/body-electrical/#wiring-and-terminals-general-diagnostics-and-tests__contents)

Was a malfunction detected?

1. YES Refer to «VERIFICATION»(ref-476788-S00315390052012060500000)
2. NO Refer to «CHECKING THE TRAFFIC LOAD ON THE CAN CABLES»(ref-476788-S06493987752012060500000)

Scheme 3

1. Connect the battery
2. Ignition on Malfunctions in the Control Area Network (CAN) may be due to a control module sending incorrect messages that disrupt normal communication. When messages are sent incorrectly, this results in a considerable increase in the amount of traffic on the Control Area Network (CAN). Check the load by measuring the average voltage value on the network cables in relation to ground. Check in the following manner: Measure the voltage between #B45 (#C45) (HS-CAN-L) and ground. The voltage shall be approx. 2.3 V. Measure the voltage between #B58 (#C58) (HS-CAN-H) and ground. The voltage shall be approx. 2.8 V. Other information see «BATTERY, DISCONNECTING»(ref-476746-S00156360512012060500000)

Is the value OK?

1. YES Refer to «INFORMATION»(ref-476788-S10927517382012060500000)
2. NO Refer to «IDENTIFYING A CONTROL MODULE IN THE CAN-NETWORK»(ref-476788-S32285499952012060500000)

See also:
• LOCATION OF COMPONENTS
• SIGNAL SPECIFICATION
• CHECKING THE POWER SUPPLY AND GROUND TERMINAL
• CHECKING WIRING AND TERMINALS
• SIGNAL SPECIFICATION
• CONTENTS