Subaru 2002 IMPREZA Service Manual page 924

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
8 CHECK INPUT VOLTAGE FOR ECM.
1)Connect the connector to ECM and oxygen
sensor.
2)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 7 (+) — Chassis ground ( − − − − ):
9 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Check
Do 0.1 and 1 V waveform pat-
terns alternately appear on the
oscilloscope screen?
Is there poor contact in ECM
connector?
EN(w/oOBD)-90
Yes
Go to step 9. Replace the oxy-
gen sensor.
Replace the oxy- Replace the ECM.
gen sensor con- <Ref. to FU(w/
nector. oOBD)-48, Engine
Control Module.>
No