Testing Quiescent Current Consumption

Preliminary work:
Testing battery charge state, Service and Repair
All assemblies and components in vehicle operating properly.







Preparing for test
If engine warm (coolant temperature >100 °C)
wait 12 minutes because of after-run cooling of heating water circulation pump.

NOTE: After switching off ignition, the heating water circulation pump switches on for 10 - 12 minutes if coolant temperature is >100 °C and cools down the engine.

Left and right front door, side window
lower.

All electrical components
switch off, e.g.:
- remove ignition key
- switch off stationary heater
- switch off car phone
- switch off radio
- fold up vanity mirror
- switch off reading lamps
- turn exterior lamp switch to position "0"
- close door, interior lighting must go out automatically after a few seconds.

NOTE: Take care not to exceed maximum current rating for multimeter; when the central locking system pump starts up a current of approx. 20 A flows.


Preparing test with quiescent current maintenance unit
Quiescent current maintenance unit (7)
connect as follows:
Ground cable (-) to battery ground (W10).
Positive cable (+) to positive pole of battery.

Quiescent current maintenance unit (7)
switch on.

Ground cable (1) at battery
disconnect.

Multimeter (2)
connect as follows; use "electrical connection set" (201 589 00 99 00) for this purpose.
Positive cable (+) to ground terminal on battery (W10).
Negative cable (-) to negative pole of battery (3).

Multimeter (2)
switch on (Mode: Amps).

Quiescent current maintenance unit (7)
switch off and disconnect

Test cable (6)
run to the right out of the trunk.

Trunk lid
close.

Commercially available tester
Multimeter e.g. Sun DMM-5
e.g. Fluke, 88
Quiescent current retention unit e.g. Hans Zeheter CMP 12.2


Preparing test without quiescent current maintenance unit
Nut on battery ground pole terminal
loosen.

NOTE: Do not disconnect ground pole terminal!
Do not interrupt circuit when pulling negative pole terminal off to prevent erasing any DTC's present. Completely disconnect the negative pole terminal only after the multimeter test cable is tightly clamped to the negative pole.

NOTE: On vehicles with auto pilot system the quiescent current increases to approx. 600 mA for approx. 30 minutes when the circuit has been interrupted!

Multimeter (2)
switch on (Mode: Amps).

Multimeter (2)
connect as follows; use "electrical connection set" (201 589 00 99 00) for this purpose.
Positive cable (+) to battery ground (W10).
Negative cable (-) to negative pole of battery (3).

Ground cable (1) at negative pole of battery (3)
pull off carefully.

NOTE: Do not interrupt circuit to avoid erasing any faults stored.

Multimeter (2) with test cable (6)
run to the right out of the trunk.

Trunk lid
close.


Commercially available tester
Multimeter e.g. Sun DMM-5
e.g. Fluke, 88







Test, Part 1 of 4






Test, Part 2 of 4






Test, Part 3 of 4






Test, Part 4 of 4