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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 >> U0159 >> U015900 (Central Electronic Module - CEM) >> Fault-Tracing Information >> Part 1

Part 1






Fault-tracing

Checking the connectors
Check that the fuse for the parking assistance system in the rear integrated relay / fusebox is intact.
Check connections on rear relay and fuse box and Parking Assistance Module (PAM) for contact resistance, oxidation and damage.
Check the cable for the power supply between the rear integrated relay / fusebox and the Parking Assistance Module (PAM). Check for an open-circuit. Check for a short-circuit to ground.
Check the ground cable for open circuit or short-circuiting to voltage. Also check the ground terminal. Check for loose connections and oxidation.

Other information
- Checking wiring and terminals Checking Wiring And Terminals





Was a fault detected?

Yes - Verification

No - Checking CAN cables

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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 information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Checking the connectors

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Checking CAN cables





Controller area network (CAN) fault-tracing

General information
Figures shown are only examples.

Note! For general information about CAN-troubleshooting, see:

- General information about fault-tracing in CAN Initial Inspection and Diagnostic Overview

General about CAN-related diagnostic trouble codes.
CEM-U000100/CEM-U000111/CEM-U000112/CEM-U000188 (HS CAN) or CEM-U001000/CEM-U001011/CEM-U001012/CEM-U001088 (MS-CAN) is generated when an electrical fault is detected in the CAN cables. Start with these diagnostic trouble codes first.
CEM-U01XX00 - CEM-U02XX00 indicates that Central electronic module (CEM) does not get a reply from, or has lost communication with, some control module on the CAN-net.
XXX-U000100/XXX-U000188 (HS-CAN) or XXX-U001000/XXX-U001088 (MS-CAN) can be generated in all CAN-connected control modules. For emission-related faults, diagnostic trouble code XXX-U007300 may also be stored. These diagnostic trouble codes indicate that the control module has detected interference on the CAN-net or another communication fault.
XXX-U010000 - XXX-U029900 can be stored in all CAN-connected control modules. These diagnostic trouble codes indicate that the control module does not receive any reply from or has lost communication with any control module on the CAN-net.
XXX-U030000 can be stored in all CAN-connected control modules except in Central electronic module (CEM). The control modules on the CAN-net listen for a message (identity number) that is sent out at regular intervals from Central electronic module (CEM). This diagnostic trouble code indicates that the control module has not received any identity number, or that the expected number is not correct. Interference on the CAN-net can also store this diagnostic trouble code.
XXX-U04XXXX - XXX-U05XXXX can be stored in all CAN-connected control modules. These diagnostic trouble codes (deviations may occur) indicate that the control module has received invalid data from another control module on the CAN-net. It may also indicate that the control module has, due to signal from another control module, limited its own functionality.

Note! In case of CAN-related faults, it is likely that a combination of above diagnostic trouble codes occur.

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.

If a communication diagnostic trouble code can be read from the control module, the malfunction is probably intermittent. Intermittent fault in the voltage supply and ground to a control module on the CAN network results in the Central electronic module (CEM) storing a diagnostic trouble code (DTC) for an open-circuit in communication with the control module where the voltage supply does not work. There will probably not be a diagnostic trouble code (DTC) in the control module where the open-circuit in the voltage supply occurred as the control module cannot store a diagnostic trouble code (DTC) when it is not supplied with power.

Note! Central electronic module (CEM) should not be replaced in case of CAN-fault, unless troubleshooting reveals that Central electronic module (CEM) has an internal fault.

Caution! During this fault-tracing use the wiring diagram to provide support when taking readings.





Continue - Checking resistance in CAN-net

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Checking resistance 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 CAN-troubleshooting, see:
- General information about fault-tracing in CAN Initial Inspection and Diagnostic Overview
Measure resistance between the following connections on the OBDII-box/diagnostics socket.
- #3 and #11. The resistance should be approx. 55 - 65 ohms.
- If resistance is approx. 120 ohms, this indicates open circuit in the circuit so that only one terminating resistor (120 ohms) has been measured.
- If resistance is above 1 kohms this indicates open circuit/high contact resistance somewhere in the circuit.
- If resistance is below 55 ohms this indicates short-circuiting/contact resistance between the CAN-lines somewhere in the circuit.

Hint: For MS-CAN (Medium Speed) the terminating resistors are located in Central electronic module (CEM) and in Driver information module (DIM).

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.

Note! Resistance measurement measures only main lines in the CAN-net (in circuit where both terminating resistors are found), not branches to certain control modules. See wiring diagram for vehicle model in question.Open circuit on branching without a terminating resistor cannot be detected with this measurement. However, short-circuiting on a branch can be detected. To measure resistance in the CAN-net to control modules located in a branching of their own, the measurement shall be done against the CAN-net at that control module. The values shall be as above.

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. Remedy as necessary.

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





Was a fault detected?

Yes - Verification

No - Checking short-circuiting to ground/voltage in CAN-net

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Checking the traffic load on the CAN cables




- 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
Faults in the CAN network may be due to a control module sending faulty messages that disrupt normal communication. When messages are sent incorrectly, this results in a considerable increase in the amount of traffic on the CAN network. The load can be checked by reading the average value of the voltage on the CAN cables in relation to ground.
Measure voltage between the following connections on the OBDII-box/diagnostics socket.
- #3 and #4 (ground). The voltage should be approx: 2,8 - 3,2 V.
- #11 and #4 (ground). The voltage should be approx: 1,8 - 2,2 V.
- #3 and #11. The voltage shall be between approx. 0.55-1.4 V. The voltage shall normally be between 0.55 - 0.90 V. A higher voltage may indicate increased traffic on the CAN-net. In case of fault in communication/too high traffic on the CAN-net, the voltage is considerably higher than the above stated values.

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.

Hint: DiCE Error Frame Finder can be used as fault detection tool if fault is suspected on the CAN-net that cannot be detected with normal troubleshooting. Interference, intermittent faults, faulty messages on the CAN-net (chattering control modules) etc., are examples of such faults. The tool registers fault messages used on the CAN-net. Fault messages may be caused by short intermittent malfunctions on the CAN-net or by a control module sending fault messages. See tools: 951 3010 (memory card) as well as associated TJ 20402.

- Ignition on.
- Connect DiCE Error Frame Finder to the diagnostics socket.
- Note the blue LED-indicator. The indicator flashes to show detection of fault messages.

Note! Certain interference may occur without any real fault!

Cable fault
- Shake the cables lightly and pull lightly on the connections during the check to locate any fault.

"Chatting" control modules
- "Chatting" control modules may be difficult to find and troubleshooting may take time. Let the vehicle stand with DiCE connected for an extended time period. Afterwards, activate functions to provoke a malfunction. It may take up to several hours before the fault messages are sent. When the indicator starts to flash, remove the fuse for one control module at a time until the indicator stops flashing. When the indicator stops flashing, restore the fuse for the relevant control module and check that the indicator starts to flash again. Then it is likely that the problem is identified.
Remedy wiring as necessary.

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





Was a fault detected?

Yes - Identifying a control module in the CAN network

No - Checking voltage-drop in cable for CAN-H and CAN-L, respectively
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