4.
Check for IAT sensor signal at idle.
caution
If the output voltage moves in reverse direction while air temperature changes,the IAT sensor is normal.
When IAT sensor is in malfunction, the default value for IAT is 20.3℃.
This is the inspection procedure to determine whether it is present DTC or memoried one by monitoring the current signal or by using the function of oscilloscope with Hi-scan pro.
Connect scan tool to DLC.
IG KEY : ON
Start engine and warm up to operating temperature.
Check for IAT sensor signal at idle.
If the output voltage moves in reverse direction while air temperature changes,the IAT sensor is normal.
When IAT sensor is in malfunction, the default value for IAT is 20.3℃.
Service standard
0℃ (32℉) : 4.0~4.4 V
20℃(68℉) : 3.0~3.8 V
40℃(104℉) : 2.5~3.0 V
80℃(176℉) : 1.0~1.5 V
This inspection procedure is recommended when service data with scan tool in not enough.
Start engine and warm up to operating temperature.
Probe(+) : IAT sensor harness connector NO3.
Probe(-) : Chassis ground.
If the output voltage moves in reverse direction while air temperature changes,the IAT sensor is normal.
Service standard
0℃ (32℉) : 4.0~4.4 V
20℃(68℉) : 3.0~3.8 V
40℃(104℉) : 2.5~3.0 V
80℃(176℉) : 1.0~1.5 V
This figure shows the waveform at terminal 3 of IATS at idle rpm.
The lower the temperature is, the closer the output voltage of IAT goes to 5 V.In case,when engine is warmed up,the output is 5 V.
Possible cause : Open signal and ground line,or sensor’s inner circuit open
In case,when engine is cold,the output is below 0.5V
Possible cause : Short between signal and groun line Bad ECM
If the output voltage moves in reverse direction while air temperature changes,the IAT sensor is normal.
In case there is no symptom and wrong data but DTC is shown
The problem may be intermittent so slightly shake the connector and harness vertically and horizontally to check if there is any data changes
If the data changes normally, the problem was intermittent so erase DTC and verify the same DTC reoccure.
Go to "Terminal and Connector inspection" procedure.
In case there is symptom and wrong data with DTC
Check open,short or connector’s connection for IATS.
Check the deterioration of IATS performance.
Go to "Circuit Inspection" procedure.
This figure shows the waveform at terminal 3 of IATS at idle rpm.
The lower the temperature is, the closer the output voltage of IAT goes to 5 V.In case,when engine is warmed up,the output is 5 V.
Possible cause : Open signal and ground line,or sensor’s inner circuit open
In case,when engine is cold,the output is below 0.5V
Possible cause : Short between signal and groun line Bad ECM
