Internal current measurement in general module

Internal current measurement via diagnosis

Diagnosis of the ZKE V general module makes it possible to read out the current values of the relay coils for the windscreen wiper relays (stage 1 and stage 2) and the relay for the headlight washer system connected to the general module.

In order to obtain an exact test result, the relay coil to be tested is activated during the test and the current value read out of the general module. The current is evaluated automatically in the test module.

Setpoints

The following setpoints apply for an operating voltage from 8 V to 16 V:

Relay coil	Current value	Remarks
Wiper Stage 1	60 - 200 mA	Coil in wiper relay K11
Wiper Stage 2	80 - 240 mA	Coil in wiper relay K11
Headlight washer	60 - 200 mA	Coil in headlight washer module K 6

Fault code evaluation

If the setpoint is reached during current measurement, the following components are OK:

Relay output in general module
Line between general module and relay
Fuse and positive supply for relay
Relay coil in relay

If the setpoint is not reached, the following faults may be detected:

Measured value	Possible causes
0 - 20 mA	Open circuit or short to ground in line from general module to relay. Break in relay coil. General module output faulty.
20 mA - 60/80 mA	Contacts oxidized. Relay coil faulty.
Greater than 200/240 mA	Short-circuit in line or relay coil to positive

The following faults cannot be detected automatically:

Relay contacts defective (load circuit of relay defective)
Line from relay to wiper motor/headlight washer pump defective
Wiper motor/headlight washer pump defective

These components are checked in the following test steps.