grid heater operation info
 

OPERATION
The air heater element is used to heat incoming air to the intake manifold. This is done to help engine starting and improve driveability with cool or cold outside temperatures.

Electrical supply for the air heater element is controlled by the Engine Control Module (ECM) through the air heater relay. Refer to Intake Manifold Air Heater Relay for more information.

One heavy-duty cable connects the air heater element to the air heater relay. This cable will supply 12 volts to an individual heating element within the heater block assembly.

CAUTION: The heater elements are no longer grounded using an external ground strap. Grounding is now accomplished using two electrically conductive gaskets. Failure to use these gaskets will result in faulty heater element operation.


The following chart displays the pre-heat, or turn-on times (in seconds) of the wait-to-start lamp. If the intake manifold temperature is above 66.09 degrees Fahrenheit, the wait-to-start lamp will not illuminate. Consequently, the intake air heater element will not be activated.




WAIT-TO-START LAMP TURN-ON TIMES
PRE-HEAT TIME WITH INTAKE TEMP AT: PRE-HEAT TIME WITH BARO AT:
19.99 IN. HG 23.00 IN. HG. 25.00 IN. HG. 26.99 IN.HG. 29.00 IN. HG.
-40.09° F 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds
-20.00° F 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds
0.00° F 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds 30.0 seconds
0.09° F 15.0 seconds 15.0 seconds 15.0 seconds 15.0 seconds 15.0 seconds
15.00° F 15.0 seconds 15.0 seconds 15.0 seconds 15.0 seconds 15.0 seconds
15.09° F 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds
32.00° F 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds
50.00° F 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds
66.00° F 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds 10.0 seconds
66.09° F 00.0 seconds 00.0 seconds 00.0 seconds 00.0 seconds 00.0 seconds

Interesting info Chris!

So it looks like 30 seconds is the max pull allowable by the batteries...

--Eric

what does the altimeter have to do with it, not that it seems to change anything.

You mean Barometer? I dont see where it changes either.