Many malfunctions in the electrical system are caused by poor harness(s) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Check the following conditions:
Check for damaged harness and terminals: contact resistance, oxidation, bent or broken terminals.
Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection
Use a suitable male pin to ensure that contact in sockets is good. The pin should remain in position when pulled gently.
Has a problem been found?
YES
Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO
System OK. Go to "Verification of Vehicle Repair" procedure
Turn ignition switch to OFF and connect HO2S(up) harness connector or HO2S(down) harness connector and ECM harness connector.
Turn ignition switch to ON
Measure voltage of HO2S(up) signal circuit between HO2S harness connector and chassis ground.
Measure voltage of HO2S(down) signal circuit between HO2S harness connector and chassis ground.
Probe(+) : HO2S(up) harness connector NO2 and HO2S(down) harness connector NO2.
Probe(-) : Chassis ground.
Specification: below 0.5V
Is voltege within specification?
YES
Go to ""Component Inspection"
NO
Short circuit to battery between HO2S harness connector and ECM harness connector
Repair as necessary and go to "Verification of Vehicle Repair" procedure
In case,when HO2S harness connector disconnected,the output voltage at terminal 2 is 12V.
▶Possible cause: Short circuit to battery in harness between E/R-J/BOX and terminal 2 of HO2S heater.
