Porsche 944 Workshop Manual page 153

944 S/944 S2
Fault, Fault Code
Test
Start the engine - fuel pump must run during engine starting.
Point 15:
DME
It not:
relay
(fuel
Turn off ignition. Disconnect control unit plug. Connect terminal 3 and terminal 24
pump) (V)
on the control unit plug with help of a test lead.
Turn on ignition - the pump must run!
It not:
Check current flow and ground paths of DME relay and fuel pump according to the
wiring diagram.
Test
Electric valve (for brake booster) will be opened more or less long depending on
Point 16:
the engine load when an engine having operating temperature is running. The
Tank
opened time is determined by a ground pulse from the control unit.
venting
valve (V)
a) Activation test
Fault
Code
Activate the tank venting valve in the "element activation" menu of the tester. It a
1_43
pulse is not heard, check power supply to terminal 1 of the electromagnetic valve
(not 944
plug according to the wiring diagram.
S)
b) Control signal test
Install DME test read (Bosch No. 1 684 463 093) between the electromagnetic
valve and plug connection. Connect and adjust engine tester according to the
supplied operating instructions.
DME - Diagnosing/Troubleshooting
Printed In Germany - XXI, 1989
Fuel System - Electronic Control
Possible Causes, Elimination, Remarks
24/28
D 24/28 - 19