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Wiring diagrams Section: Body Electrical

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Central Electronic Module (Cem) & Accessory Electronic Module (Aem) Diagnostic Trouble Codes: Overview Volvo V70 II

Body Electrical 9 illustrations ~3503 words

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: Use the Service. Wiring diagram to provide support when taking readings. 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.

Also 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

See «General information about fault-tracing in the CAN network»(ref-441117-S34302411522011121500000)

Continue Refer to «Checking the resistance of the control area network (CAN) cables»(ref-406910-S33868867892011070100000)

Scheme 278

Scheme 278: Checking the resistance of the control area network (CAN) cables

Scheme 279

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
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). See the appropriate SYSTEM WIRING DIAGRAM article. 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. See the appropriate SYSTEM WIRING DIAGRAM article. 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-406825-S28150951272011070100000) See «Checking wiring and terminals»(/volvo/v70/ii-2000-2004/remont/body-electrical/#electrical-general-diagnostics-and-tests)

Is the value OK?

YES Refer to «Checking a short-circuit in CAN cables»(ref-406910-S36367527622011070100000)
NO Refer to «Identifying fault causes in the CAN network»(ref-406910-S35122740402011070100000)

HINT: Use the appropriate SYSTEM WIRING DIAGRAM article to provide support when taking readings. 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.

Other information

See «General information about fault-tracing in the CAN network»(ref-406825-S27490473802011070100000)

Continue Refer to «Checking the resistance of the control area network (CAN) cables»(ref-406910-S16025394592011070100000)

Identification

Identifying the stop lamp

Scheme 280

Scheme 280: Identification

A version 1 stop lamp can be identified as follows

The P/N (1), stamped onto the left-hand side of the stop lamp, is 9154503
the connector (1) on the stop lamp has a smooth surface facing downwards and an enclosing collar.

A version 2 stop lamp can be identified as follows

The P/N (2), stamped onto the left-hand side of the stop lamp, is 9483132
the connector (2) on the stop lamp has a smooth surface facing upwards.

Removing loose paper

Remove loose paper from the inside of the headlining where the stop lamp was located.

Note. Do not damage the headlining.

Replacing the stop lamp to the same model

If the stop lamp is being replaced with one of the same model, no modifications need to be made. Continue with: Installing components.

Replacing the stop lamp, version 1 to version 2

If a version 1 stop (brake) lamp is replaced with a version 2 stop (brake) lamp (see Identifying the stop lamp ) the cables should exchange positions (change polarity). See Reversing polarity of cables.

HINT: For general information about fault-tracing the control area network (CAN), see the linked document below. General information about fault-tracing in the CAN network

In order to check the control area network (CAN) cables, the resistance in the network must be measured. The resistance between the two CAN cables, with the network connected, must be 60ohms in both the high speed network and the low speed network.

Note. Resistance will only be 60 ohms if the main artery of the CAN network is whole and the network is connected. If the main artery of the CAN network is split somewhere and a reading is taken between the CAN cables, resistance will be 120 ohms. For further information, see the appropriate SYSTEM WIRING DIAGRAM article.

If diagnostic trouble codes (DTCs) can be read off from the relevant control module, the fault is probably intermittent. The locations that must be checked in the event of a fault in the low speed network are the junctions behind the central electronic module (CEM) and the audio module (AUM) as well as the cable harness behind the Audio module (AUM).

Intermittent fault in the current supply to the actual control module is indicated by the DTC in the Central electronic module (CEM) (CEM-1A5X or CEM-1A6X). There is probably no diagnostic trouble code (DTC) in the relevant control module as the control module cannot store a diagnostic trouble code (DTC) when it is without power.

Continue Refer to «Checking the resistance of the control area network (CAN) cables»(ref-406910-S34839324772011070100000)

Scheme 281

Scheme 281: Checking the resistance of the control area network (CAN) cables

Disconnect the battery negative lead. The network must not be powered when taking resistance readings. Otherwise an incorrect value may be obtained.
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 readings taken from there. Readings can even be taken in the connector for the Power seat module (PSM). The advantage of the adapter wiring to the Central electronic module (CEM) is that all control module can be connected in the network when taking readings and access can be gained to both the high speed and low speed networks. The resistance reading only measures the main arteries in the low speed network, not the junctions that exist for different control modules. For further information, see the appropriate SYSTEM WIRING DIAGRAM article. When taking readings on the high speed network When taking readings on the high speed network the adapter wiring should be connected to the Engine control module (ECM) and readings taken from there. The Engine control module (ECM) must be connected. This resistance reading only measures the main arteries in the high speed network. For further information, see the appropriate SYSTEM WIRING DIAGRAM article. Connect an ohmmeter to the terminals for CAN-L and CAN-H on the relevant network. Turn the contacts and turn the cable harness. Resistance must be approximately 60 ohms. NOTE: Resistance will only be 60 ohms if the main artery of the CAN network is whole and the network is connected. If the main artery of the CAN network is split somewhere and a reading is taken between the CAN cables, resistance will be 120 ohms. For further information, see the appropriate SYSTEM WIRING DIAGRAM article. Other information See «Battery, disconnecting»(ref-406866-S10988298012011070100000) See «Connecting the breakout box»(ref-406825-S28150951272011070100000) See «Checking wiring and terminals»(/volvo/v70/ii-2000-2004/remont/body-electrical/#electrical-general-diagnostics-and-tests)

Is the value OK?

YES Refer to «Checking a short-circuit in CAN cables»(ref-406910-S42068771942011070100000)
NO Refer to «Identifying fault causes in the CAN network»(ref-406910-S38032963882011070100000)

Note. Figures shown are only examples.

HINT: For general information about CAN-troubleshooting, see

Scheme 282

Scheme 282: General information

INFORMATION/PRODUCT SPECIFICATIONS/Design and function/37/CAN-net. General about CAN-related diagnostic trouble codes. CEM-DF01 - DF17 can only be stored in Central electronic module (CEM). These diagnostic trouble codes are stored when an electric fault is detected in CAN-lines. Start with these diagnostic trouble codes first. CEM-1AXX only stored in Central electronic module (CEM). One diagnostic trouble code for every control module on the CAN-net. These diagnostic trouble codes indicate that Central electronic module (CEM) does not receive any reply from other control modules. XXX-E000 (HS-CAN)/E001 (LS-CAN) can be stored in all CAN-connected control modules. These diagnostic trouble codes indicate that the control module has detected interference on the CAN-net. XXX-E003 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. 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 diagnostic trouble codes (DTCs) for communication faults can be read off from a control module, the fault 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 Refer to «Checking resistance in CAN-net»(ref-406910-S12792672832011070100000)

Scheme 283

Scheme 283: Checking resistance in CAN-net

Scheme 284

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: INFORMATION/PRODUCT SPECIFICATIONS/Design and function/37/CAN-net. See «General information about fault-tracing in the CAN network»(ref-441117-S34302411522011121500000) 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 LS-CAN ( ), terminating resistors are located in Upper electronic module (UEM) and Rear electronic module (REM). 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 as necessary. Other information See «Battery, disconnecting»(ref-406866-S10988298012011070100000) See «Checking wiring and terminals»(/volvo/v70/ii-2000-2004/remont/body-electrical/#electrical-general-diagnostics-and-tests)

Was a fault detected?

YES Refer to «Verification»(ref-406910-S41643141512011070100000)
NO Refer to «Checking short-circuiting to ground/voltage in CAN-net»(ref-406910-S11032330352011070100000)

Scheme 285

Scheme 285: Checking the amount of traffic on the LS-CAN

Scheme 286

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: 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. For further information, see the appropriate SYSTEM WIRING DIAGRAM article. 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 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 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. Note the blue LED-indicator. "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 See «Battery, disconnecting»(ref-406866-S10988298012011070100000) See «Checking wiring and terminals»(/volvo/v70/ii-2000-2004/remont/body-electrical/#electrical-general-diagnostics-and-tests)