Fmtv transmission radiator fan running

[serpico760]

I do not know if my transmission radiator fan was working in the proper manner before, but I noticed underneath a connector that wasn't fully connected in and had pulled halfway out and I thought it was related to the ABS since my ABS light is on. I pushed in the connector all the way and now when I turn my truck on before I even start it the radiator fan for the transmission comes on. Isn't that only supposed to come on when it's needed and not just as soon as you turn the dash power switch on? Might this mean that there's some sort of temperature sensor that's malfunctioning and thinking it's over a temp when it's not?

 

[Ronmar]

The aux trans fan runs in parallel with the engine fan...

 

[Ronmar]

So if your engine fan is not locked up when you turn on the ignition, then the aux fan relay or circuit may have an issue. Like the fan solenoid, de-energized = fan on. This on a 3126? If i recall correctly the ECU may engage it untill the engine starts... wull have to look that up...

 

[serpico760]

So if your engine fan is not locked up when you turn on the ignition, then the aux fan relay or circuit may have an issue. Like the fan solenoid, de-energized = fan on. This on a 3126? If i recall correctly the ECU may engage it untill the engine starts... wull have to look that up...

Thank you for the reply, my engine fan works as when I'm driving it around for a while I can hear it come on and go off as necessary. Since all the rest of that is so loud I never knew whether or not the transmission fan was going on at the same time or not. Yes it's an early A1, 2001 it's a 3126. I'll check the dash breakers and see if anything is tripped

 

[Ronmar]

Or you could start the engine, get out of the truck and see if the aux fan is still on…

Another way to test it is turn on the ignition, and when the aux fan starts up, turn on the fording switch and see if that stops it. The fording sw provides power to the aux fan relay and the engine fan solenoid the exact same way the ECM does. If the fording sw stops the aux fan then the control circuit is OK.

Forget the discussion but I seem to recall this is a normal occurrence until engine start Allows the ECU to provide the fan control power. The fact you have noticed your engine fan cycling normally indicates the ECU is providing proper control signals…

Unless you are trying to move 20-30K + pounds of cargo, the liquid heatex should meet all your trans cooling needs anyway just like on every other 4X LMTV, and you could probably leave that fan disabled…

 

[ramdough]

Or you could start the engine, get out of the truck and see if the aux fan is still on…

Another way to test it is turn on the ignition, and when the aux fan starts up, turn on the fording switch and see if that stops it. The fording sw provides power to the aux fan relay and the engine fan solenoid the exact same way the ECM does. If the fording sw stops the aux fan then the control circuit is OK.

Forget the discussion but I seem to recall this is a normal occurrence until engine start Allows the ECU to provide the fan control power. The fact you have noticed your engine fan cycling normally indicates the ECU is providing proper control signals…

Unless you are trying to move 20-30K + pounds of cargo, the liquid heatex should meet all your trans cooling needs anyway just like on every other 4X LMTV, and you could probably leave that fan disabled…

My transmission fan kicks on just before ignition. 1999 A1….. or at least it did…. Need to reconnect the wires.


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[serpico760]

Or you could start the engine, get out of the truck and see if the aux fan is still on…

Another way to test it is turn on the ignition, and when the aux fan starts up, turn on the fording switch and see if that stops it. The fording sw provides power to the aux fan relay and the engine fan solenoid the exact same way the ECM does. If the fording sw stops the aux fan then the control circuit is OK.

Forget the discussion but I seem to recall this is a normal occurrence until engine start Allows the ECU to provide the fan control power. The fact you have noticed your engine fan cycling normally indicates the ECU is providing proper control signals…

Unless you are trying to move 20-30K + pounds of cargo, the liquid heatex should meet all your trans cooling needs anyway just like on every other 4X LMTV, and you could probably leave that fan disabled…

I did notice last night that if I turn on the fording switch, the transmission fan turns off and I can hear the air valve for the engine fan switch do something. I haven't tested yet whether it turns off when you start the engine as I'm plumbing in an M35 air horn and haven't got everything sealed right yet so I don't want to start it. Weird thing is the air horn was leaking out of its solenoid. Not just the air connection portions of the solenoid but out of the ring around the edge and out of the wire connection holes! So what I did was removed it and cleaned it, put thin CA glue around the edges that were leaking to let it wick in and seal it. Also on the inside edge where there was a seal next to where the valve plunger is I put thin CA glue there and let it seep in. Then I reinstalled it with permatex liquid thread sealant. I'm going to wait till Sunday to test it out giving the sealant plenty of time to set up.

 

[Ronmar]

Well if the fording sw controls them and the engine fan works normally when driving I suspect your aux fan control is working normally. If you are not doing any more work than a 4X4 could, then the thermal diverter really isn’t even sending any trans fluid to that cooler and all the heat is exiting out thru the engine cooling system anyway…