Control Module Fault Tracing - Signal Missing: Other Volvo S80 I

Identifying a control module in the CAN network

HINT: Use the illustration to provide support when taking readings.

For general information about CAN-troubleshooting, see

1. See «General information about fault-tracing in the CAN network»(ref-461659-S07700657672012040200000)

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.

If the load on the CAN network is too high, this may be due to a control module sending faulty messages on the CAN network (known as 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 faults can occur without a diagnostic trouble code (DTC) being stored by the control modules. 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(s) that stored the diagnostic trouble code (DTC) that is communicating faultily. 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.

1. Ignition on.
2. 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.

1. #6 and #14. 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. Higher voltage may indicate increased traffic on the CAN-net. n 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 individual control modules, other diagnostic trouble codes (DTCs) may be stored in certain 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. witch 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.

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. or certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery o "restart" the control module/CAN-net.

Scheme 1266

1. Continue Refer to «Verification»(ref-461658-S37833396562012040200000)

Verification

HINT: After rectifying a fault, a verification should be carried out.

Scheme 1267

1. Reinstall the connectors, components etc.
2. Ignition on. NOTE: For certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery o "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. Read out the diagnostic trouble codes in the vehicle via the DIAGNOSTICS tab.

Does the diagnostic trouble code (DTC) for faulty communication return?

1. YES 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.
2. NO OKAY: Troubleshooting has been completed.

Scheme 1268

1. Ignition off.
2. Disconnect the battery negative lead.
3. Connect OBDII-Box (951 3015) to the diagnostics socket. HINT: Use the illustration to provide support when taking readings. For general information about CAN-troubleshooting, see: See «General information about fault-tracing in the CAN network»(ref-461659-S07700657672012040200000) 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 (Scheme 1268) 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 (Scheme 1268). 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 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. or certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery o "restart" the control module/CAN-net. Remedy wiring as necessary. Other information See «Battery, disconnecting»(ref-440259-S31019869382011121400000) See «Checking wiring and terminals»(ref-440209-S33835172972011121400000)

Was a fault detected?

1. YES Refer to «Verification»(ref-461658-S37833396562012040200000)
2. NO Refer to «Checking the traffic load on the CAN cables»(ref-461658-S33251834752012040200000)

Scheme 1269

1. Connect the battery.
2. Ignition on.
3. Connect OBDII-Box (951 3015) to the diagnostics socket. HINT: Use the illustration to provide support when taking readings. For general information about CAN-troubleshooting, see: See «General information about fault-tracing in the CAN network»(ref-461659-S07700657672012040200000) In principle, the voltage measured in each cable in the CAN-net shall be the same at each control module in the network. his means that the voltage-drop in the cable for CAN-H and CAN-L, respectively, between the control modules should be very low. f there is a voltage-difference in the CAN-lines between the diagnostics socket/Central electronic module (CEM) and a control module due to, e.. 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. or certain faults in the CAN-net where control modules have stopped communicating, it may help to disconnect/reconnect the battery o "restart" the control module/CAN-net. Remedy wiring as necessary. Other information See «Checking wiring and terminals»(ref-440209-S33835172972011121400000)

1. Continue Refer to «Verification»(ref-461658-S37833396562012040200000)