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
Checking open circuit of IATS signal line is to find whether there is open or short circuit in MAP harness.
Turn ignition switch to OFF and disconnect IATS connector.
Turn ignition switch to ON
Measure voltage of IATS signal circuit between MAP harness connector and ECM harness connector.
Probe(+) : IATS harness connector NO3.
Probe(-) : Chassis ground.
Specification: Approximately 5V
Is voltage within Specification?
YES
Go to "Inspection of open ground line"
NO
In case over 5V : Short circuit to battery between IATS harness connector and ECM harness connector
In case 0V : Open or short circuit between IATS harness connector and ECM harness connector
Repair as necessary and go to "Verification of Vehicle Repair" procedure
1.In case,when IATS connector is disconnected,the voltage of IATS terminal 3 is 0 V.
▶Possible cause: Open or short between terminal 42 of ECM and Terminal 3 of IATS
When the ground line is open,ECM assumes the air temperature as -39℃ and outputs 5 V.
Turn ignition switch to OFF and disconnect IATS harness connector.
Measure resistance or voltage of IATS ground circuit between IATS harness connector and chassis ground.
Probe(+) : IATS harness connector NO4.
Probe(-) : chassis ground.
Specification: below 1Ω ,below 0.5V
Does each resistance indicate continuity circuit?
YES
Go to "Component Inspection"
NO
Open circuit between IATS harness connector and ECM harness connector
Open circuit between ECM harness connector and chassis ground
Repair as necessary and go to "Verification of Vehicle Repair" procedure
In case,when checking open ground circuit,the resistence is infinite.
▶Possible cause: Open or short between terminal 36 of ECM and Terminal 4 of IAT
