Porsche DME 7.8 — OBD II Diagnosis Manual / PAGE 1097
DME 7.8 DME 7.8 0 · 0-198P1657
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DME 7.8 DME 7.8 0
0-198P1657
274 Overrun Recirculating Air Valve Output Stage -
Open Circuit
Diagnosis conditions
• Engine running
• Battery positive voltage greater than 7 V
Possible fault cause
♦Open circuit
♦Open circuit in B+ supply
♦Overrun recirculating air valve
Affected terminals
III/16
Diagnosis/Troubleshooting
Note!
The wiring for the overrun recirculating air valve is routed via the connector X 59/3 pin 8.
Work instruction Display OK If not OK
1 Check triggering wire for ♦Connect special tool 9637 to 0 - 5 Ω
continuity. wiring harness (DME control
module plug).
♦Remove plug connection of
overrun recirculating air valve.
♦Measure resistance between III/
16 and overrun recirculating air
valve connector pin 1
2 Check B+ supply for over- ♦Remove plug connection of Battery voltage.
run recirculating air valve. overrun recirculating air valve.
♦Switch on the ignition.
♦Measure voltage between over-
run recirculating air valve pin 2
and ground.
3 Check overrun recirculat- ♦Measure overrun recirculating 20 - 26 Ω at 20° C.
ing air valve resistance. air valve resistance between pin
1 and 2.
2138 P1657 0-198 page 1
Printed in Germany – 3, 2001 p1657
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