Help Check Engine Light!

[Robert]

It depends. When certain codes are cleared, it will clear your CEL immediately. Others require a certain number of Complete Drive Cycles to be completed before it will clear your CEL. A complete drive cycle for the most part is starting your vehicle after it hasn't been driven for 6-8 hours, your coolant temperature is below a certain value, you drive a certain number of miles in city and then a certain number of miles on the highway. Your manual will tell you what the actual requirements are. If fixing the IAT requires several successful drive cycles before clearing then you will have to meet the requirements, clear the CEL with a scanner or disconnect your battery for a few minutes. If you clear the light and then it comes back on then the problem is still there. I know when I've disconnected my IAC connector while my engine was running, I forced a CEL. As soon as I plugged it back in and restared my Explorer the light was out. I haven't tried it with the IAT sensor though. If I remember to try it tomorrow I'll give it a try and let you know what I find.

 

[BadAzzexplr]

Thanks for your replys Robert. If you can I would like to see if that does happen. What kind of code reader do you have?

 

[Robert]

I have the AutoXray Pro-Pak (www.autoxray.com). Here is what I have found out. With my engine running, I disconnected my IAT. It did not set a code. With my IAT disconnected my temperature was reading -40F. I shut off my Explorer and started it right back up. This time the CEL came on when I started it. I scanned the code and it was a P0113 (IAT sensor reading too high). I plugged the sensor back in. Shut off my Explorer and restarted it a couple of times. The light did not clear even though the IAT sensor was connected and working properly (verified the temperature).

What this means is that the PCM only tests the IAT on start-up. When the connector is bad (disconnected) it will read -40F. Fixing the problem and then restarting the Explorer will not immediately clear the CEL. It is one of the codes that require a certain sequence to clear it. I suppose disconnecting the battery will clear the light though. I didn't try that, I cleared it with my scanner.

 

[BadAzzexplr]

thanks for your reply and your effort to help fix my problem. I am sending the truck in this friday, because I don't have the equipment measure the IAT. I will keep you posted on what they do.


Thanks again Robert

 

[BadAzzexplr]

Well, I drove the truck today and its REALLY BAD now. It's begining to shake now and the check engine light is blinking on and off. It sounds like its backfire when idling. I gotta drive the truck another 100 miles before it makes it for Friday.

Does the check engine when its blinking mean anything more then it on solid?

 

[Robert]

It doesn't say in my Owner's Manual but I remember reading something like if your CEL is flashing you need immediate attention. The few times my CEL has came on, it came on steady with no driveability problems. Mine has never flashed. From what you are describing, I don't think I would try driving it another 100 miles before service.

 

[BadAzzexplr]

well i brought the truck in and one of the plug wires was burnt. Replaced all the wires and good as new, but the code is still there.

PC112 Intake Air Temp Low Circuit.

I have two questions now:

1)The throttle posistion switch has a bolt on the top of it covering the throttle cable, but I am missing a bolt on the side, is there any wires suppose to be connected to there and what type of bolt holds it on?

2) Anyway way to measure what the IAT is reading without a computer?

 

[Robert]

What side was the burnt plug wire on? If it was the passenger side, any chance that whatever burnt the plug wire may have burn the harness with the IAT wires in it?

I can't picture what you are talking about regarding the throttle, mine is a SOHC V6. Since yours is a V8 the throttle might be different.

I'm sure you could mesure the resistance of the IAT sensor with a multimeter, but I wouldn't know what the expected resistance would be.