DIY PGMFI Diagnostics - Code 10 IAT

Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!


No part of this DIY is to be reproduced with out acknowledgment of the site and author it came from, ie me and ozhonda.com. Do not rip parts off and claim them as your own.



IAT sensor "Intake Air Temperature" also known as TA "Temperature Air" Sensor. The IAT sensor is commonly located on the front or rear side of Intake Manifold, however on OBDII cars its located on the intake air tube. The ECU uses the IAT to measure Air density to help calculate fuel ratio.



Aim:

Diagnose code 10.

http://ecu-man.com/diy/pgmfi/mil/pgmfi-code-10.gif





Required:

Basic Testing

- Digital Multi Meter
- paper clip






Symptoms

A faulty IAT sensor to trigger code 10, you will more than likely get the engine light come on and the car will go into limp mode, Limp mode is a preset fuel and ignition map running on a backup processor in the ECU. Limited to about 3500rpm and a rich mixture to protect the engine the engine will run, but not the best. Common cause for code 10 is a faulty IAT or open circuit in the wiring back to the ECU.



Basic Test


- Perform a Visual inspection and make sure the IAT sensor is Connected


IAT Sensor Pin out Picture


http://ecu-man.com/diy/pgmfi/iat/PGMFI-iat-conn.JPG

wire side of connector


**** Voltage Test ****


Set your multi meter to DC Volts ( 20v scale )

Step 1 ( Reference Voltage test )


Note:The Sensor signal wire could vary from Pin 1 or Pin 2, your best bet is to pick the red/yellow wire.
Check the IAT sensor for its Reference Voltage from the ECU, Note that the reference voltage wire is also the signal wire. Connect the Black Lead from your multi meter to the chassis for a good ground. Back probe* the IAT with the Red lead to Pin 2 of the IAT sensor while the sensor is disconnected.

KOEO* you must get 5v

If you get 5v proceed to step 2,


if you do not get 5v, try Pin 1 of the IAT ( incase its wired differently ) repair open or short circuit to ECU from Pin 2 of IAT (red/yellow wire) to the bellow ECU Pin ( also see continuity test below )

OBDO = C5
OBDI = C15
OBDIIa = D8
OBDIIb = C25


If you do not get 5v from the ECU pin above, replace the ECU.




STEP 2

Check IAT sensor for a good ground. Leave your Red lead from the above test on Pin 2 (red/yellow wire) of the IAT. Back probe your Black lead into Pin 1 of the IAT. ( Blue or Green/blue wire )

KOEO* you must get 5v

If you get 5v proceed to step 3,


if you do not get 5v, repair open or short circuit to ECU from Pin 1 of IAT to the bellow ECU Pin ( also see continuity test below )

OBDO = C12
OBDI = C22
OBDIIa = D11
OBDIIb = C18


Leave your Black lead of the multi meter as is and move the Red Lead from Pin 2 of the IAT to the positive battery terminal. You should get 12v. If not, repair the wire between Pin 2 of the IAT and Pin listed above to the ECU.


STEP 3


Check the IAT Signal. Connect the Black Lead from your multi meter to the chassis for a good ground. Back probe* the IAT with the Red lead to Pin 2 ( red/yellow wire ) of the IAT sensor while the sensor is connected.


KOER* you should get 1v to 2 v with a hot engine. and about 3v to 5v with a cold engine



as engine intake air temperature increases IAT voltage decreases

If you do not get a signal on Pin 2 but just get 5v, replace the IAT sensor with a known good one and retest. If you do get a signal at Pin 2, then check the signal at the ECU end.



OBDO = C5
OBDI = C15
OBDIIa = D8
OBDIIb = C25



If you get a good signal at Pin 2 ( red/yellow wire ) on the IAT and no signal on the above ECU Pin, repair the Open circuit between the above ECU Pin and Pin 2 ( red/yellow wire ) of the IAT.


***** Its is always best to check sensor inputs at the ECU side *****







**** Continuity Test ****


Set your multi meter to continuity. This setting is mostly a picture if a sound .))) when you touch the Red and Black leads together on your meter it should beep.


STEP 1

make sure the Ignition is off and unplug the IAT Connector and the ECU Connectors for this test

Continuity test between IAT Pin 1 ( blue or green/blue wire ) and ECU, Connect your Red multi meter lead on the IAT Pin 1, Back probe* the Black multi meter lead on the ECU Pin below that suits your car.




OBDO = C12
OBDI = C22
OBDIIa = D11
OBDIIb = C18





your multi meter should beep and read short or 000.0ohms.



STEP 2

make sure the Ignition is off and unplug the IAT Connector and the ECU Connectors for this test

Continuity test between IAT Pin 2 ( red/yellow wire ) and ECU, Connect your Red multi meter lead on the IAT Pin 2, Back probe* the Black multi meter lead on the ECU Pin below that suits your car.




OBDO = C5
OBDI = C15
OBDIIa = D8
OBDIIb = C25



your multi meter should beep and read short or 000.0ohms. Place the black multi meter lead on a good ground source. You should not get beeping, this is testing for short to ground.




**** Resistance Test **** Set the multi meter to ohms ( 1M scale )



Unplug the IAT sensor, connect your Red multi meter lead to Pin 1 of the IAT. Connect your Black multi meter lead to Pin 2 of the IAT.


with the IAT at 0deg C the resistance should be about 5k ohm

with the IAT at 60deg C the resistance should be about 500 ohm






* Notes

KOEO = Key On Engine Off

KOER = Key On Engine Running

Back probe the sensor, use a paperclip and push it into the connector then touch/clip your multi meter lead to the paper clip




Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!