How Does it work? FFM Heater

[GM Guy]

I was wondering how the FFM heater is energized, and roughly what temp does it engage?

 

[Green Machine]

IIRC, the computer controls it. I've heard it turns on below 40*F. The 12v power comes from the same fuse the glow plug relay runs off of i think...

 

[GM Guy]

what if it is on a 92 or 93?

 

[THEFERMANATOR]

The heater has powe all the time from the fuse panel, but it has a thermister switch built into the element that turns it on and off at about 40-65 degrees. It works completely on it's own just like most other diesel engines out there do. I know that DODGE does it this way on the 12 valves and at least the early 24 valves, and my DURAMAX does it this way as well. The ECM does monitor the 12V+ circuit to the heater to make sure it has power to it, but it doesn't control it. Newer diesels I believe though the ECM controls it.

 

[GM Guy]

well, that is easy to understand, thanks!

 

[Matt Bachand]

The heater has powe all the time from the fuse panel, but it has a thermister switch built into the element that turns it on and off at about 40-65 degrees. It works completely on it's own just like most other diesel engines out there do. I know that DODGE does it this way on the 12 valves and at least the early 24 valves, and my DURAMAX does it this way as well. The ECM does monitor the 12V+ circuit to the heater to make sure it has power to it, but it doesn't control it. Newer diesels I believe though the ECM controls it.

Is that standard for fuel heaters? Meaning do you think my Racor heater is the same way, meaning I can leave it ign switch constant power and it wont be used when its not necessary?

 

[THEFERMANATOR]

Most all of them I have seen work that way, but I know there are some that work off of a switch. It's easy enough to test them though. On a hot day hook it to a battery and see if the elemnt begins to warm up. If it does then it needs to be switched.

 

[bison]

Most all of them I have seen work that way, but I know there are some that work off of a switch. It's easy enough to test them though. On a hot day hook it to a battery and see if the elemnt begins to warm up. If it does then it needs to be switched.

i think you ment a freezing cold day,

 

[THEFERMANATOR]

i think you ment a freezing cold day,

If it gets warm on a hot day then that meas it doesn't have the temp switch built into it. If it has the temp switch thermioster in them they will only warm the element if they are about 60 degrees or colder.

 

[bison]

If it gets warm on a hot day then that meas it doesn't have the temp switch built into it. If it has the temp switch thermioster in them they will only warm the element if they are about 60 degrees or colder.

Kinda redundant aint it,having a fuel heater on in hot weater.
i rather have a fuel cooler in hot weather.