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Home >> Volvo >> 2013 >> XC60 R Design AWD L6-3.0L Turbo VIN 90 B6304T4 >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> U Code Charts >> U0104 >> U010400 (Central Electronic Module - CEM) >> Fault-Tracing Information >> Part 4

Part 4







Checking short-circuiting to ground/voltage in CAN-net




- Ignition off.
- Disconnect the battery negative lead.
- Connect OBDII-Box (951 3015) to the diagnostics socket.

Hint: Use the wiring diagram to provide support when taking readings.

For general information about fault-tracing the control area network (CAN), see the linked document below.
- General information about fault-tracing in CAN Initial Inspection and Diagnostic Overview

Checking for a short-circuit to ground
Measure resistance between the following connections on the OBDII-box/diagnostics socket.
- #6 and #4 (ground). Measurement is shown in the figure. The resistance should be above 1 kohms.
- #14 and #4 (ground). The resistance should be above 1 kohms.
If resistance is below 1 kohms this indicates short-circuiting between the CAN-line and ground.

Checking for a short-circuit to voltage
Measure resistance between the following connections on the OBDII-box/diagnostics socket.
- #6 and #16 (voltage). Measurement is shown in the figure. The resistance should be above 1 kohms.
- #14 and #16 (voltage). The resistance should be above 1 kohms.
If resistance is below 1 kohms this indicates short-circuiting between the CAN-line and ground.
Twist the cable harness and wiggle connectors where they can be accessed along the cable harness during every measurement, and note if the resistance changes to detect intermittent short-circuits or open circuit.

Hint: Part the CAN-net at suitable points to decide where a short-circuit may be found.

Note! After fault with control modules that interfere with communication, other control modules may remain in Limp-Home (that is, they work with reduced functionality) even when the ignition has been turned off and on a few times. For certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery to "restart" the control module/CAN-net.

Remedy wiring as necessary.

Other information
- Battery, disconnecting Battery, Disconnecting
- Checking wiring and terminals Checking Wiring And Terminals





Was a fault detected?

Yes - Verification

No - Checking the traffic load on the CAN cables

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Checking voltage-drop in cable for CAN-H and CAN-L, respectively




- Connect the battery.
- Ignition on.
- Connect OBDII-Box (951 3015) to the diagnostics socket.

Hint: Use the wiring diagram to provide support when taking readings.

For general information about CAN-troubleshooting, see:
- General information about fault-tracing in CAN Initial Inspection and Diagnostic Overview
In principle, the voltage measured in each cable in the CAN-net shall be the same at each control module in the network. This means that the voltage-drop in the cable for CAN-H and CAN-L, respectively, between the control modules should be very low. If there is a voltage-difference in the CAN-lines between the diagnostics socket/Central electronic module (CEM) and a control module due to, e.g., contact resistance in a connector or branching, communication may be lost/interfered with.
Check if there is voltage-drop in the cable for CAN-H and CAN-L between the diagnostics socket/Central electronic module (CEM) and the control module where there is problem with communication.
Carry out the following:
Measure voltage between the following connections on the OBDII-box/diagnostics socket.
- #6 and corresponding connection on relevant control module for CAN-H. The voltage shall be lower than 50 mV.
- #14 and corresponding connection on relevant control module for CAN-L. The voltage shall be lower than 50 mV.
If voltage is too high, this indicates too high contact resistance in cable, connector, or branching. Check the circuit between the diagnostics socket and control module in question for contact resistance and oxidation.

Note! After fault with control modules that interfere with communication, other control modules may remain in Limp-Home (that is, they work with reduced functionality) even when the ignition has been turned off and on a few times. For certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery to "restart" the control module/CAN-net.

Remedy wiring as necessary.

Other information
- Checking wiring and terminals Checking Wiring And Terminals





Continue - Verification

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No Fault Found - No Fault Found

DONE - DONE

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off
- Reinstall the connectors, components etc.
- Switch on the ignition for at least 10 seconds.
Try communicating with the control module by selecting one of the functions for vehicle communication under the Diagnostic tab.

Is communication established?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information
Information
FAULT-TRACING FAILED - No Fault Found

Attempt New Test - Checking the power supply

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