air intake heater sticking on ??

[Prairie Dog]

So the MAP gives a temperature? I thought it provided manifold pressure input to the ECM?

 

[AH64ID]

So the MAP gives a temperature? I thought it provided manifold pressure input to the ECM?

It does both. I have my SGII setup so I can see MAP temp/pressure and IAT temp/pressure. The MAP temp is what the ECM uses as the IAT, and the IAT temp is what the ECM uses as ambient temp (and is really only used, from what I can tell, for post-heating). You can watch IAT rise and fall with grid heater operation and that can only be from the intake manifold.



The IAT pressure is used to determine total boost, and I have been watching it to look at intake system restriction under WOT. I have also been watching the ambient temp from the IAT sensor to watch CAC efficiency, as well as my winter "warm air intake" mode efficiency.

 

[Prairie Dog]

Very interesting - thanks AH64ID.

 

[List]

I had the batteries load tested and theywere OK. This mourning the grid heater knicked in even though the block heater was plugged in but it turned off after a minute or so. this makes me think more and more a sensor is going bad. the reference to the relays is something I've thought about too. It still starts and runs fine so I'll take my good ole time diagnosing it or until it quits.

 

[AH64ID]

My grids worked this morning also, and I had been plugged in for about 90 minutes... thou it was 4° outside. My grids wont fire after 90 minutes of block heater if its above 20° outside, with the winter front. Without the winter front my block heater isn't nearly as effective.

I still haven't read anything that indicates there is for sure an issue.

If you want to verify your sensors a Scan Gauge II can read the temp/pressure from you IAT and MAP sensor.

 

[JJPage]

Just because it changes does not mean there is osmething wrong. Very true, but if the OP is in tune with his truck, as I am with mine(and I know you are also), any change is suspect.



Too many failure points to pin point an issue or even say the operation is not "normal". I agree cerb, lots of possibilities to try and pinpoint from a forum, but, you can state it is not "normal", and it still may be in acceptable parameters, however "you know" all is not correct.

For all the reasons you and AH64ID put forth, that all appears normal, you both are most likely correct... I Respect you both, and have utilized/abused your experience many times in the past, and plan too going forward:-laf



Merry Christmas, Jess

 

[analog]

rbattelle and AH64ID,

Thank you very much for the information you posted to this thread. It is very helpful in furthering my understanding of the systems in this truck!

 

[mwilson]

Found this interesting...



Still running the '06, putting it back in storage Saturday.



My road was glare ice this morning thanks to a spurt of 50 degree weather and rain on top of packed snow.



Noticed lights were dimming and brightening back up far more quickly than normal for a 50 degree start.



Released my death grip on the old coffee cup and started looking around at things.



Guess what??



When it spins over 15mph and you then let off, then touch the throttle again the grid heaters cycle depending on wheel spin. Over 15mph, under 15mph, over 15mph repeat... ... ... .



Quite an event when you are about half awake... ... .



Mike.