Please help. I need to pass emissions in next week. My check engine light is on. I am getting codes p0112 (intake air temp low) and p1496 ( 5 volt supply low) So far I replaced the IAT sensor and the ECT sensor. I have checked for continuity between the black/lite blue wires and ground at IAT, MAP, ECT, and TPS. There is continuity at all those spots. I have probed all those sensors and received 5 volts at all of them. I spayed contact cleaner at the connections at the sensors and pcm. I clear the codes with my code reader but they come right back when I turn the key off and back on (engine not running).. I am at a loss at what to check next??

Oh, And also once in a while the engine will surge while driving for a split second and the check engine light will turn off then immediately back on in the blink of an eye. I'm not sure is the surge is related or not. I just want to get the light off and pass emissions.

 

I don't have the book for your car! I think you need to do voltage drop test while the car is running! Maybe clean the ground terminals its probly a wad of wires right on your block somewhere!For the ground wires you do ground to ground voltage drop testing!

Here's video, different car, differnt code, testing theory the same!

 

Thank you for the video. Iam gonna watch it right now. I got a better code reader today and it tells me the IAT temp is 261 degree. no matter if engine has been running for a while or if its completly cold. I hope the ground thing works I will try it in the morning.

 

What doe's it read with the sensor unplugged. Should be around -40.

Also get reading of ECT sensor, it shares same ground,do it with plug on and off

 

Sorry for the wait. I was gone last night.. The IAT read 261 degree F and Coolant 81 degrees F with the IAT plugged in and running. The IAT read 261 degrees F and Coolant read 91 degrees with IAT unplugged and engine running.

 

Also I noticed with it plugged in I get like 3.8 volts but unplugged it gets 5 volts on multimeter. But the sensor is brand new

 

A quick test would be with the meter connected . Move the wiring harness around see if it changes!

That Ground is shared whit 9 other sensors! You could also start unpluging them 1 at a time, watching the meter for change. With the key ON!

 

Thanks im trying it now. I have tried wiggling and disconnecting all sensors except crank and battery as I cant seem to find the battery sensor.. Alldata says its on the bumper so im looking

 

Check that downstreem heated 02 senssor wire for melting! That sensor is on the circuit also.

The list I came up with:

For the 2.7 95-2000............I know you said you have the 2.5 eng so there may be a difference!!!!!!!!!!!!
Shared grd circuit!

IAT
MAP
CRANK
CAM
TPS
AC pressure tranducer
Down stream 02
Batt temp
Vec speed sensor

 

I can not find anything thats makes the voltage change. I have a diagram showing all 9 other sensors but still no change. Only thing I noticed was when I found the battery temp sensor. I removed the fog light and a wire on the fog light is the same color as the sensor grounds. Fog lights have not worked since I got the car last month. I wonder if it could be somewhere in a ground for those