Porsche 928 Workshop Manual page 612

928 S4
928 GT
Fuel System I Electronic Control
28
Fault, Fault Code
Possible Causes, Elimination, Remarks
Test point 1
Idle speed contact bd
Ground short
Break
Fault code 2-12
Check with circuit input test, using 9288
system tester or 9268 tester
9268 tester
Select the test step and depress the accelerator pedal.
9288 display:
Idle speed contact closed
Idle speed contact open
9268 display:
1332 (idle speed contact closed)
0000 (idle speed contact open).
If the display does not change,
disconnect the plugs from the EZK and LH control units,
Using test leads, connect ohmmeter between terminals 8
and 18.
35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 2Q 19
Display:
Throttle valve closed
Throttle valve opening angle
-z IOR
>l"=mQ
If the idle speed contact values are not reached during this
test, it must be repeated directly at the throttle valve switch:
Pull off plug at throttle valve switch. Connect ohmmeter between ter-
minals 2 and 3 of the throttle valve switch, using test leads.
Display:
Throttle valve closed
< 10n
0 - ri
Throttle valve opening angle > 1" = m Q
Check that setting is correct and adjust if
necessary.
Possible cause: incorrectly adjusted throttle valve switch or accelera-
tor cable.
EZK-Diagnosis/Troubleshooting
Printed in Germany - XXV, 1990
D28-5