98 k1500 5.7 P0112 code

[Drippy]

I have a 98 k1500 throwing mass air and IAT codes replaced the mass air sensor and the IAT sensor cleared codes and about 10 miles after it throws the codes again. Traced harness to check for freys or cut wires leading to the ecm but did not find any. Kinda stumped on this. All readings for fuel system and vaccum system are great. Even tested voltage to the IAT and it was running at its 5v. any help or suggestions would be great.

 

[Supercharged111]

What do they show on the data stream? And what codes are you throwing?

 

[Drippy]

What do they show on the data stream? And what codes are you throwing?

P0112 code​

data stream show anywhere from 2-7 g/s on idle and about 18-20 g/s around 1800-2500 rpms. everything is perfect the engine was rebuild fully 3000 miles back but its throwing Mass air sensor and IAT sensor codes even after replaces both components and clearing codes its saying a low circuit to the IAT but all the voltages to everything are great

 

[Supercharged111]

What about the MAF code? Can you ohm the IAT from the PCM plug end to end? Just because 5V is reaching the sensor and you have a good sensor doesn't mean the return path is OK. I don't have any schematics nearby, but if you are throwing codes for both it makes me wonder if they don't share a ground somewhere and that's messed up.

 

[Drippy]

I just went to go start my truck let it idle for about 10 minutes. No check engine is on anymore but it still is throwing the p0112 on scan it has a really rough idle. These are the live stats.

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[Supercharged111]

If you go for a drive or wiggle the harness does that IAT jump around? The PCM is getting a low return for that sensor.

 

[Drippy]

it does a little bit but not a huge spike

 

[east302]

May be a short in the harness if the value changes when you shake things around. Here’s the diagnostic from the 98 service manual. Full PDF versions can be downloaded at this link:

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

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