Porsche 1989 944 S2, Workshop Manual

Page: 153 / 167

944 S/944 S2 Fuel System - Electronic Control
24/28
Fault, Fault Code Possible Causes, Elimination, Remarks
Test
Point 15:
DME
relay
(fuel
pump) (V)
Start the engine - fuel pump must run during engine starting.
It not:
Turn off ignition. Disconnect control unit plug. Connect terminal 3 and terminal 24
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
Point 16:
Tank
venting
valve (V)
Fault
Code
1_43
(not 944
S)
Electric valve (for brake booster) will be opened more or less long depending on
the engine load when an engine having operating temperature is running. The
opened time is determined by a ground pulse from the control unit.
a) Activation test
Activate the tank venting valve in the "element activation" menu of the tester. It a
pulse is not heard, check power supply to terminal 1 of the electromagnetic valve
plug according to the wiring diagram.
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
D 24/28 - 19