Porsche 928 Workshop Manual page 314

928 Engine - Cooling
19
Function-testing the output stage
1.) Plugs I and II must be connected
to the control unit.
4.) Function-testing the control
signal of the output stage.
Reconnect output-stage plug
connector. Remove cover from
plug I of control unit.
2.) Checking voltage supply.
Connect voltmeter to pin 3
(ground) and pin 4 (plus) of
the fan output-stage plug
connector.
Reading: battery voltage
3.) Connect voltmeter to pin 3
(ground) and pin 2 (plus).
Ignition on
Reading: battery voltage
c '.,
Engine temperature-z79'C(175"F)
Measure the voltage with an
analog voltmeter with an
external resistance
(Ri) 100 k0hm.
Pin 7, plug I (ground) and pin 6
(plus).
Ignition on
Press AC button
Set the air-distribution slide
switch to up/down.
Reading: approx. 7 V
0
Printed in Germany-XX,1988
Function-testing the
19
- 25
Output Stage