Fault-Tracing Information And Testing the Electrical Generating

Fault-tracing and testing the voltage supply system

Check the battery, starter motor and generator terminals and cables for loose, corroded or damaged cable terminals and wiring.
Check the generator (GEN) charge current and charge voltage.

Ensure that the freewheeling generator pulley functions correctly (where applicable):
- Rev the engine to 3,000 rpm. No extra electrical consumers should be switched on.
- Switch off the engine. Check that the generator rotates for longer than the engine.
In cold weather, the battery warning lamp in the combined instrument panel may light up for a few seconds after start. This is because the freewheel may require a few revolutions to heat up the bearing grease. A battery warning lamp which is continuously lit may indicate a freewheel which does not lock against the generator (GEN) rotor shaft.
Check the auxiliary belt tension. Inspect the belt for wear.
Measure the vehicle's stand by voltage consumption (below).

Measuring the stand-by current consumption
Checking standby current Checking Standby Current
Calculating the maximum permissible stand-by voltage

Identify the capacity of the battery in the car in order to calculate the maximum permitted stand-by voltage.
Formula
*Ah / 504 h / 4 = I mA
(* = the battery capacity, I = the stand-by current)
E.g.:
capacity / 3 weeks * 25% = stand by voltage
65 Ah / 504 h * 0.25 =32.2 mA