X2 2100 code 40-intake heater?

[reeferj]

Hi, i got a unit carrier, X2 2100 with advance controller coming up a code 40: check intake heater. I checked these:

1. 80amp fuse is good.
2. no power(12V) at intake heater terminal before&after engine starts (engine coolant temp is below 32F).
3. check GPR relay, it is good.
4. GPR relay terminal 87 to intake heater terminal shows continuity.

but i found voltage(12V&11V) at both terminals(85&86) of the GPR relay control side whenever ON/OFF switch is on. That's why the GPR relay is not pulled down to energize the intake heater circuit.It's supposed to be some time delayed, right?

What i think is this: when ON/OFF switch is on, power (12V) at GPR relay terminal 85, then grounded terminal 86. After a few seconds, when engine is started, power then is supplied to terminal 86 to de-energize the GPR relay. Am I right about this understanding?

If i am right, then there is something wrong with the board,even the software.

can any one explain this in details, please? Thanks a lot!

[gravy258]

you'll have to talk positive and negative power.

from what I understand everything has positive power to it, the micro supplies the negative to switch the relay or activate a valve.

[moggy66]

do you have 12v @ pin 30 on the GPR? when unit is switched ON?

[reeferj]

do you have 12v @ pin 30 on the GPR? when unit is switched ON?


Yes. Power is always on pin 30.

[moggy66]

Yes. Power is always on pin 30.
Yes it should be , you should have 12v at 85 OR 86 not to both, the other side is ground through the micro.so by reading your post you are getting 12v to the relay on both sides may have two wires rubbed togehter;)

[reeferj]

those wires running to different direction, it is in good condition.

[moggy66]

So pin 85 should be a ground and not have 12V on it, this goes back to 5MPA9

[DaButcher]

relay ground, what your reading as voltage is actually voltage drop

[reeferj]

Thanks everyone. I fixed it by replacing a board. No codes coming up anymore.