HAC Circuit? (1 Viewer)

[71FJ40]

Is there a HAC (High Altitude Compensation) circuit on these trucks? Or atmospheric pressure sensor?
And if so, does anyone have a pic from the FSM that shows the components in the circuit?

The issue is that above 9000 ft, the VSC and check engine lights come on, then go back off when I go to lower elevations.

Open to other ideas/thoughts.

 

[71FJ40]

Anyone? - as I am routinely travelling between 5000ft and 12k feet, this issue is starting to annoy me

 

[Hokie LX]

The ECU may just not be used to running at that altitude and therefore it is outside of its learned fuel map parameters from the elevation it runs at most of the time. I would imagine if you stayed there for a couple days the map would adjust and the light would go off but quick sprints up to high altitudes may be causing it to throw a CEL.

 

[87warrior]

What codes are you seeing with the CEL?

I do not believe there is any altitude compensation circuit or air pressure sensor in the 100.

 

[71FJ40]

The ECU may just not be used to running at that altitude and therefore it is outside of its learned fuel map parameters from the elevation it runs at most of the time. I would imagine if you stayed there for a couple days the map would adjust and the light would go off but quick sprints up to high altitudes may be causing it to throw a CEL.

I have lived at 11,800 feet with this 100 series since 2006. So its not that

 

[71FJ40]

What codes are you seeing with the CEL?

I do not believe there is any altitude compensation circuit or air pressure sensor in the 100.

Will pull the codes