XC70 L5-2.5L Turbo VIN 59 B5254T2 (2003)
Note! The VIDA cart cannot be connected when taking this reading. If VIDA is connected, the CAN network will never go into sleep
mode as VIDA will ensure that there is still traffic. Use a free-standing measuring instrument instead and take the reading directly on the
adapter wiring.
The voltage between the green and white CAN cables must drop to 0 V. No activity (pulses) should be measurable on the network. If there is activity, cut
the power to the control modules that are constantly powered (Steering wheel module (SWM), Upper electronic module (UEM), Rear electronic module
(REM), Driver's door module (DDM), Passenger door module (PDM), "VOLVO On-call Plus" Phone module (PHM), Accessory electronic module
(AEM) and Central electronic module (CEM)) one by one in that order until the voltage drops to 0 V and no activity can be seen on the CAN network.
Use the relevant fuses for the control modules to cut their power. Do not disconnect them physically as this can affect other control modules on the CAN
network
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The control module to which the power was cut last when the CAN network voltage dropped to 0 V and the activity ceased is probably the faulty
control module that is keeping the network active. If the passenger door module (PDM) or driver door module (DDM) is considered to be faulty,
these can be disconnected physically from the CAN network as they are not connected in series in the CAN network. Note which control module
causes the network voltage to drop to 0 V to determine which of the two is faulty. Do not replace both the driver's door module (DDM) and the
passenger door module (PDM) as a pair. Fault-trace until the source of the fault has been found
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Verify that the correct control module was faulty by repeating the fault, with and without the faulty control module connected in the CAN network.
The above method cannot be used if the suspected control module is powered from the ignition switch, as these control modules would not
discharge the battery.
Case 2
"Disruptive control modules". The advantage of these cases is that there are usually diagnostic trouble codes (DTCs) stored, for example E001 and
CEM-1A51-1A64. The method described below can be used to distinguish between a wiring-related CAN fault, which is the most common, and a
"disruptive control module". The most common customer complaint is that the indicators in the driver information module (DIM) drop to the 0-position.
See also: Information about the CAN network, structure and function See: Description and Operation/Information About the CAN Network, Structure
And Function
Both "babbling control modules" and "disruptive control modules" can have intermittent faults that are not necessarily apparent when the car is in the
workshop. In some cases, "disruptive control modules" do not set diagnostic trouble codes (DTCs). The following method should therefore be used to
fault-trace:
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Measure the voltage between the green and white CAN cables in the relevant CAN network. The average voltage value is normally 0.5 V
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If a control module is "disruptive", the voltage is usually above 0.7 V
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If this is the case, cut the power to the control modules in accordance with the method described about to find the fault cause
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Verify that the correct control module was faulty by repeating the fault, with and without the faulty control module connected in the CAN network.
Note! Following faults with "babbling" or "disruptive" control modules, some control modules may remain in "Limp-home mode" even after
the ignition key has been removed and inserted in the ignition switch again. To remedy this, disconnect and reconnect the battery negative
terminal to restore the control modules to normal function.
