Signal Missing
Signal missing
Checking the function of the audio module (AUM)
Check the power supply for the control module by switching on the radio or playing a CD. There must be sound from the radio or CD.
Note! Radio reception may be poor indoors. On certain cars, the radio reception may deteriorate if the trunk lid is open.
Is there sound from the radio?
Yes - Checking communication with the audio module (AUM)
No - Checking the power supply and ground for the audio module (AUM)
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Checking the power supply and ground for the audio module (AUM)
Check the fuses for the main unit/audio module (AUM).
Note! If a fuse is blown, check the circuit after the fuse before replacing the fuse. Check for a short-circuit to ground. Then replace the fuse. For further information about the circuit after the fuse, see the relevant wiring diagram.
Check the connector for the main unit/audio module (AUM). Check for contact resistance and oxidation.
Check the power supply cable for the main unit/audio module (AUM). Check for an open-circuit.
Check the ground cable between the main unit/audio module (AUM) and the ground terminal. Check for an open-circuit. Also check the ground terminal. Check for contact resistance and oxidation.
Remedy as necessary.
Other information:
- Radio cassette player, replacing
- Checking wiring and terminals Checking Wiring And Terminals
Was a fault detected?
Yes - Checking the function of the audio module (AUM)
No - Checking communication with the audio module (AUM)
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Checking communication with the audio module (AUM)
Hint: The CAN communication with the control module is probably OK if the control module ID can be read off. The fault is probably intermittent and may therefore be difficult to locate.
- Try to communicate with the audio module (AUM) by reading off the control module ID
- Click on the symbol for VCT2000 to begin reading off
Continue - Signal missing
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Signal missing
General information
Note! Figures shown are only examples.
Hint: For general information about CAN-troubleshooting, see:
- General information about fault-tracing in the CAN network General Information About Fault-Tracing In The CAN Network
General about CAN-related diagnostic trouble codes.
CEM-DF01 - DF17can 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
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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 the CAN network General Information About Fault-Tracing In The CAN Network
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 (Low Speed), 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
- Battery, disconnecting Battery, Disconnecting
- Checking wiring and terminals Checking Wiring And Terminals
Was a fault detected?
Yes -
No -
------------------------
Checking the amount of traffic on the LS-CAN
- 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 wiring diagram.
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. 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
- Battery, disconnecting Battery, Disconnecting
- Troubleshooting using DiCE Error Frame Finder Troubleshooting Using DiCE Error Frame Finder
- Checking wiring and terminals Checking Wiring And Terminals
Was a fault detected?
Yes -
No -
------------------------
Identifying a control module in the CAN network
Hint: Use the wiring diagram to provide support when taking readings.
For general information about CAN-troubleshooting, see:
- General information about fault-tracing in the CAN network General Information About Fault-Tracing In The CAN Network
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. If the load on the CAN network is too high, this may be due to a control module transmitting faulty messages on the CAN network. This is called a disruptive control module. The fault may also be due to an intermittent short-circuit to supply voltage or ground in one of the CAN cables. This results in the control modules on the CAN network starting to send faulty messages. The fault may occur without any of the control modules storing a diagnostic trouble code (DTC). The voltage can be measured between the CAN cables in order to check the load on the CAN network.
Note! It is not necessarily the control module that has set the diagnostic trouble code that communicates incorrectly. Faulty messages can come from any control module in the same section of the CAN network. However, faulty communication in one network cannot affect the communication on the other network. In other words, faulty communication on the LS-CAN cannot disrupt communication on the HS-CAN and vice versa.
- Ignition on.
- Connect OBDII-Box (951 3015) to the diagnostics socket.
Check communication/load on CAN-net by measuring voltage between CAN-L and CAN-H. Measure voltage between the following connections on the OBDII-box/diagnostics socket.
- #3 and #11. The average value of the voltage must be approximately 0.6-1.4 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.
In order to identify which control module has faulty communication, cut the power supply to one control module at a time. Check the voltage in the CAN cables again. The easiest way to cut the power supply is to remove the fuse(s) for the relevant control module. Repeat until the voltage between the CAN wiring drops to the normal level.
Note! When connecting and disconnecting certain control modules, diagnostic trouble codes (DTCs) may be stored in other control modules.
Hint: When the suspected defective control module has been identified, connect and disconnect the supply voltage to the control module a number of times to verify that the malfunction appears and disappears. Switch off the ignition between each check.
Note! Do not cut the power to the central electronic module (CEM) unless it is the last control module left to check.
A control module that is communicating incorrectly must be replaced. See Repairing and installing/Removing, replacing and installing.
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.
Continue -
------------------------
Verification
Hint: After rectifying a fault, a verification should be carried out.
- Reinstall the connectors, components etc.
- Ignition on.
Note! 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.
- Erase diagnostic trouble codes (DTCs) in all control modules.
- Ignition off.
- Ignition on.
- Start the vehicle. Allow the vehicle to run for 10 minutes. Start the engine. Allow the engine to run at idle speed for 10 minutes
- Read out the diagnostic trouble codes in the vehicle.
Does the diagnostic trouble code (DTC) for faulty communication return?
Yes -
No - FAULT FOUND
------------------------
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 -
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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 CAN-troubleshooting, see:
- General information about fault-tracing in the CAN network General Information About Fault-Tracing In The CAN Network
Checking for a short-circuit to ground
Measure resistance between the following connections on the OBDII-box/diagnostics socket.
- #3 and #4 (ground). Measurement is shown in the figure. The resistance should be above 1 kohms.
- #11 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.
- #3 and #16 (voltage). Measurement is shown in the figure. The resistance should be above 1 kohms.
- #11 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 voltage cable.
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 as necessary.
Other information
- Battery, disconnecting Battery, Disconnecting
- Checking wiring and terminals Checking Wiring And Terminals
Was a fault detected?
Yes -
No -
-------------------------------------------------
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 the CAN network General Information About Fault-Tracing In The CAN Network
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.
- #3 and corresponding connection on relevant control module for CAN-H. The voltage shall be lower than 50 mV.
- #11 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 -
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No Fault Found - No Fault Found
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Checking the function of the audio module (AUM)
Hint: After carrying out the repair, check that the fault has been remedied.
- Ignition off
- Reconnect the connectors. Reinstall the components
- Ignition on.
Check the power supply for the control module by switching on the radio or playing a CD.
There must be sound from the radio or CD.
Note! Radio reception may be poor indoors. On certain cars, the radio reception may deteriorate if the trunk lid is open.
Is there sound from the radio?
Yes - FAULT FOUND
No - Fault-tracing information
-------------------------------------------------
Fault-tracing information
Information
Attempt New Test - Checking the function of the audio module (AUM)
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