Oil Pressure Switch

[DennyDay]

I installed an oil pressure switch on my 01 to shut of the intake heater as soon as oil pressure comes up. I simply disconnected the OEM ground wires to the relays, and the system works very well. If I do this on my 2006 with a 5. 9 will it screw up the OEM electrical system or the ECM? Has any one done this on an 06?

Very common mod on Second Gen.



Denny

 

[DennyDay]

No one has a clue?



Denny

 

[Tinman]

I'm just guessing, but I bet the ECM won't like it. I say this based on experience with other electrical issue with trying to modified things.

 

[rbattelle]

I don't really see where the ECM will care. I know things are drastically different from 2003-2006, but unless they added a grid heater voltage monitor, the ECM won't care.

If the ECM does care, you'll know the first time you try it. Then you can just plug things back the way they were.

But I really doubt the ECM is going to care. To test it out, try simply removing the ground (effectively disabling the grids) and see what happens.

Ryan

 

[betterthanstock]

According to my info, the ECM will set codes if the (low power) relay circuits are interrupted, but will not set codes if the heater circuits are disconnected, except maybe a code and a possible power derating for cold intake temp. when it expects it to be warmer (during cold start) .

But disconnecting the ground like you suggest, may need a little load resistor to fool the ECM. ???

Try it. The worst that can happen is a couple of codes, and derated power when cold.

 

[rbattelle]

But disconnecting the ground like you suggest, may need a little load resistor to fool the ECM. ???

Try it. The worst that can happen is a couple of codes, and derated power when cold.

I was assuming he meant pulling the ground on the heater itself, rather than the relay. Obviously, I wasn't thinking straight.



So I checked the PDM and you're absolutely right - the ECM has the ability to detect high/low voltage at the heater grid relays.



Then all you have to do is put your own relays after the existing relays, which you can then turn on/off at will. Piece of cake, and the ECM has no idea what you're doing.



On pre-2006 trucks I'm not sure how (or whether) this will effect the logic that supresses voltmeter readings during heater operation. I suspect that since the ECM will think the heaters are functioning even though you've bypassed them, then you'll still get depression of the voltmeter.



Does the ECM derate power when IAT is very low? I wasn't aware it did so...



Ryan

 

[DennyDay]

Some good ideas - - The way I will use it, if the temp is in the 10-15 degree range, I will cycle the heaters twice, then start the engine, the oil pressure switch will not allow the heaters to operate as soon as the oil pressure comes up. Did this on my '01 with no ill effect, but the electrical system on the

'06 is not forgiving. The horn blew and the turn signals flashed when I hooked up an extra backup light with out a relay.

This truck is a whole lot smarter than I am!



rbattelle - -As you suggested, I'm going to try unplugging the ground and trying it before I put the rest of the stuff in the system.



Denny