Engine/Transmission (1994 - 1998) What controls the grid heater?

[DPinkston]

I just bought a 97 Cummins engine to stuff into my 93 Ford. I got all the wiring harness but didn't get the computer. I didn't think I needed it but now I'm not so sure. What cycles/controls the grid heater? I got the solenoids off the fender skirt. I have been told that the only thing that the computer does on these is control the alternator output. Is this correct? I plan to use my old Ford alternator anyway.

Thanks.

Danny

 

[Howard Durand]

There are two elements in the grid heater assembly and the PCM controls the cycling. I believe that only one element is turned on at a time due to the large amount of current they draw and each one is only on for just a few seconds for the same reason. If either one is left on too long, it will probably burn in two.



If you are an electronic wizard, you could devise a scheme to let you manually cycle them without the PCM. There are time delay relay circuits that could be made to handle the job quite well.



In reality, depending on where you are located, you may not need them.

 

[DPinkston]

I am not an electronics wizard but I know some people who are. I won't worry about the grid heater right now. If someone could tell me the maximum safe on time I may just devise a pushbutton setup as a temporary measure and make sure I do not exceed that.

Danny

 

[Howard Durand]

The manual states that at 0 degrees F, the elements can be energized for 30 seconds each. At 10 degrees, 15 seconds and at 59 degrees, 10 seconds.

Energizing them too long would probably not burn them in two but would certainly draw down the batteries fast.



For anyone that is interested, there is a web site, www.electronickits.com, that has a huge assortment of electronic kits at very reasonable prices. Among them are several versions of time delay relays that could easily be used to control your grid heater relays.

 

[Hohn]

Yes, 30 seconds is safe based on the OEM usage. When it's really cold, you'll see that the light takes this long to go out.



Previous TDR posts show that the grid heaters draw over 90 AMPS when activated! That's enough to hurt a battery pretty quickly.



Time to invest in an Odyssey battery

 

[BCaldwell]

I live near Vancouver B. C. and with my old 91 never had an issue with starting even when below freezing temps, I could hit the key without letting the grid heaters cycle and the truck would fire up without any problem. The gh would still cycle after startup until a little heat built up in the cylinders but as long as the battery was healthy I had no problems with startups. Also the early 91 and before trucks did not have computers so must of had some sort of timer to control the gh it may be easier to go thet route if you need the heaters. Bill