S 600 (221.176) V12-5.5L Turbo (275.953) (2007)
On-board electrical network line pyrofuse (N82/1f1)
In the vehicle power supply control unit (N82/1) there is a pyrofuse (picture 4) to protect the on-board electrical network line to the prefuse box
(F32).
The on-board electrical network line pyrofuse (N82/1f1) is triggered under the following conditions:
1.
Temperature of on-board electrical network line higher than 140°C.
^
As of software number 221 442 03 55, the pyrofuse is no longer triggered on the basis of temperature (as of 08/05). Only crash signal 2 is
relevant.
2.
Crash signal 2 from airbag control unit (ARCADE).
Brief instructions, quiescent current fault diagnosis
Procedure for vehicles with discharged on-board electrical system battery:
1.
Using Star Diagnosis (DAS), read out the last and next to last entry for bus keepawake event detection. Compare both entries with each other:
-
If fewer than 4 entries exist, check the appropriate control units. Inspect and replace, if necessary.
-
If there are more than 4 entries, the CAN system is extremely unstable and the information is unusable.
-
With gateway control units, always check the associated CAN system too.
2.
Prepare the vehicle for the quiescent current test:
-
Close the latches of the doors, trunk lid and engine hood.
-
The charging converter must be deactivated.
-
After switching off the engine, briefly turn the key in the EIS to position 2, then back to position 0, and then remove.
-
The quiescent current switch must not be allowed to open during the quiescent current test. Both batteries must therefore have a voltage of
mm. 12.2 V.
3.
Perform the quiescent current test on the ground cable of the on-board electrical system battery.
-
Use the current clamp or non-interrupted looped-in multimeter.
-
Isolate the active CAN system.
-
If the quiescent current is higher than 2.5 - 3.0 A, there is a "bus keepawake event" in the on-board electrical system.
-
Identify the bus keepawake event control unit.
-
Identification by means of voltage measurements at the fuses and disconnection of the intermediate gateways.
-
Disconnect the control units one by one from the CAN voltage distributor and reconnect if the quiescent current is unchanged.
-
If the quiescent current consumption is lower than 2.5 - 3.0 A without CAN bus or MOST ring activity, there is a problem in a local control