So I think I may have a bad sensor. I got these codes.

112-Intake Air Temp Sensor Voltage low
237-Map Sensor Voltage too low
1475-Aux 5 volt output too high
1693-DTC Detected in ECM or PCM

I interpreted them as my truck saying "Hey, I'm low on power and there is no way it can be that cold" I figure that either I have a bad connection or the sensor is bad for the first 2 and the bottom one. The aux 5 I don't really know about, but figured if that is related to the other two it might be reading high because it refrences the other too. I unhooked it and hooked it back up and then the light went off after a few starts. The light came back on and I noticed the skinny pedal was pretty sluggish and I wouldn't get more than 15 psi even if I floored it. If I turned the chip up it would pull boost, but still seemed like it wasn't fueling. The Attitude said the air was 114 and wouldn't change (it is teens here) but it still was getting a boost reading. What do you guys think? Just get a new sensor?

 

sounds like your AIT has gone out if your not getting good boost.

 

Yea, I figured it was the IAT because I watch it every once in a while and even in the summer it usually won't be that hot. At least it is easy to change, I had asked a dealer about the cost of a new one last spring and they said like 400 something. I found the cummins part number and it was like 60 or 70, is there that much of a mark up at the dealer or did I miss something?

 

60-70 sounds right for a cummins part. I think napa would have one for around 40-50, quality would be of a concern to me though so I would stick with the cummins part.

 

Are you sure the second code is 137 and not "237"? I am leaning towards the map sensor. 1475 refers to map sensor voltage. When diagnosing the 1475 code, it tells you to see if the truck passes or fails the boost pressure test. The bad thing here is all these codes could be caused by a bad of failing "ECM" or a bad wire. If you want, I can email you the diagnostic flow charts that tell you the how to check each code and check voltages. It will tell you possible causes and what to do for each code. Let me know...

 

yea, it was 237 I fat fingered that when I typed it in. Yea, that would be great. I'll PM you my email. I am really thinking it is the sensor getting a bad connection because after it threw the codes the first time I played with the connection and the light went off after a few restarts and then came back on. I've been watching the intake air temp on the edge and it sits right at 114 almost all the time, every once in a while it will jump around a little, so I figure that the problem is between the sensor and the edge which is just the one connection and the wires going to the edge, well I guess unless it is the supply voltage to the sensor.

 

Ok, so I thought it might have been a bad connection at the MAP sensor because the plastic was cracked so it wouldn't lock together like it was supposed to. I replaced that and it didn't go away so I stopped by the local cummins shop (if you are any where near Grand Forks ND I highly recommend them) and they hooked up the diagnostic tool and we played around with all the connections and stuff (disconnected all the aftermarket stuff to see if it was a problem with any of that or their harnesses). The IAT read 1.4 volts with the key on and truck off (corresponds to like 147 degrees or something like that), the MAP read 1.0 Volts. We tinkered cleared codes and stuff and it always tripped it immediatly. We fooled around with it for a little over an hour (which was half an hour after close and they still didn't want to charge me anything). The next day I spent some time trouble shooting stuff in my grandpa's shop. I checked resistances between pins on the sensors and in the harness and everything seems to be working fine there. The problem is the thing is so intermittent with the truck off. I had the edge on so I could read the IAT hoping that I could wiggle stuff and figure out but it keeps jumping around when the truck is off (between correct and the default value.) Should I just replace the IAT? What would make one go bad?

Parts and Service thank you for the flow charts I went through all of those as best I could (I remembered most of the values for some of the cells from the cummins shop so I it was almost like I had a scan tool.)

 

Might as well try a sensor since the harness checked out good.

 

Ok, the truck now has new map and IAT sensors and I've cleaned all the connections. I haven't gotten a chance to clear the codes yet but the edge is still reading 114 degrees for the IAT so I don't think it is fixed.Parts/Servicesent me some helpful flow charts and the cummins shop gave me some wiring diagrams but I still haven't been able to figure it out.Any one have any suggestions?

 

I played find the electrical gremlinfor a while, went TDY for a couple weeks and now I have finally decided I have had enough with this problem and dropped my poor girl off at the cummins shop. They have tinkered with it for a couple hours and haven't been able to figure it out either. They were going to look some more today but aren't sure if they are going to be able to find the problem. What do I do?