Engine/Transmission (1998.5 - 2002) sensors

[JPearsonIII]

how can you check the iat & map sensors to know if they are performing correct? on my 2002 3500. all new to this so please bear with me. thanks

 

[DieselDave]

Welcome, I would suggest that you borrow or buy a scan tool that can read the trouble codes in the ECU and also allow you tp look at the live data stream from the sensors. There is an abundance of information to be had from a scan tool. The voltages read from the sensors using the scan tool can then be referenced to typical voltage ranges as listed in the servicve manual for your truck.



This is really the only logical way to check these sensors with any level of confidence. Good luck!

Dave

 

[DieselDave]

What are your trouble symptoms? More details might help us to help you more.

Dave

 

[Gary - K7GLD]

A quick way to check system error codes, is to switch the ignition on, but not far enough to engage the starter - then quickly back off - do that 3 times rapidly, leaving the ignition on the last time. The truck's electronics system goes into an error check mode, with any error codes displayed in the odometer window. Give it time to do the complete test and return to the mileage display mode before switching the ignition off - have a pencil and paper handy to write down any error codes seen, and get back to us with those numbers. This system test will display all sorts of errors, current ones, or past ones that haven't yet been cleared - including the IAT and MAP sensors.



Good luck.

 

[monkeyman]

The IAT gets full of Soot and can be cleaned. A little trick getting out, if you take bolt that holds Fuel T on tappet cover its easier. The Map sensor at idle should read 5 volts I think its the Blue wire but check first. You can also clean the Map Sensor.
Rick

 

[Fishin Guide]

A buddy and I made up a test rig for MAP sensors. It allows you to screw the sensor into a regulated air source. Also, we use a regulated voltage depending on the year of the truck.



We can see the MAP voltage change as we change pressures. BTW< the factory MAP has a range near 60psi. While the factory ECM may not use all that info, it's just good to know I think.



Dave

 

[FLynes]

If you do clean the IAT sensor (it will be crudded up if you have a lot of miles and/or an exhaust brake), carb cleaner works wonders. When you put it back in, do NOT torque it to 10lb/ft as per the repair manual!!! I found this out the hard way. Finger tighten it and then use your socket to tighten it the rest of the way, till it feels snug. The plug (at least on mine) will be flat parallel with the ground, when you look at it.