1984 Ford F150 pickup. I have traced a parasitic drain on my truck's battery (that kills battery overnight), and the drain is traced to my truck's 'Electronic Engine Control Relay' (EEC Relay). This EEC relay is located under the dash. The EEC Relay is Part #E47F-12A646-A1A (written on side of relay). I unplugged the relay and the battery drain ceased (as ascertained by ammeter check of current draw on battery before and after). With the relay removed the truck still starts and runs. So I am wondering this. What is the purpose of the Electronic Engine Control Relay? Can I drive my truck with the Electronic Engine Control Relay removed? ( although the relay itself may be ok, it is obviously part of a problem that drains my battery. There may be a short somewhere that is the cause of the relay being energized even when the truck is parked and engine NOT running. The continuously energized relay drains my battery dead. So I remove the relay and the battery drain stops. So I would like just to leave the relay out if that is ok). Please send your comments and observations. Is it ok to leave the relay out? Who needs it if the truck will run ok without it.
Thanks in advance for your feedback.

 

Apparently your truck has been converted? The EEC relay powers the computer and it's controls on the engine. It will not run without the EEC relay if it was wired as original. If someone put a different dist and carb on it, and took all the other stuff off, then you do not need the computer or the EEC relay.

 

what if you have the original distributor but have an aftermarket carb ?

 

fast68: If you have the EEC still operating then you need the EEC relay and probably at least some of the original carburetor solenoids if the aftermarket carburetor didn't come equipped with suitable replacements. If the EEC has been removed then you need a distributor/ignition system using vacuum/mechanical advance and you don't need the EEC relay and many other EEC related components.

 

Re: your input concerning my 1984 F150, thanks. I am still digging into this. I am still processing the revelations that are your responses and information about the EEC relay and EEC system. I am at least 2nd owner of truck, which was way old when I got it, and maybe the EEC system had already been 'converted'. I want to look at all this.

 

First of all, I realize that this is revisiting an old topic, but I found this as I was searching for information. [Great feature... the "Search" button!]

Franklin2, I respect your input and value your knowledge. I am going to share what has recently happened to my son's 1984 F-150 with the 4.9L engine and maybe we all can learn something from this.

He is in the ARMY and was recently on a 3 week field exercise. When he returned, the battery [good/fairly new] was completely flat. It resisted being jumped off until extensive idling of the other vehicle prior to starting. Under the circumstances, he replaced the battery. Well, soon the battery was dead again after sitting for a couple of days. He had to disconnect the negative battery each night until he could go to a mechanic.

The mechanic traced the electrical draw to the EEC Relay. Once it was removed, the draw stopped. The local Ford dealer found one at another dealer. It would have been $110 + $30 for "overnight". The parts guy at the dealership [a good guy] called Autozone and gave them the correct numbers. Autozone could have the part today and it was $12.00 and some change [I would much rather have Motorcraft, but...].

Anyway, the relay was removed and yet the truck still starts and runs. From what my son described, it is in the "safe" or "limp home" mode. His truck is about as stock as they come. He loves originality. I purchased the truck years ago from the original owner. It still has the plastic vacuum lines, feedback carb and distributor, air pump, EGR, catalytic converters, etc!

Perhaps the removed relay still allows a route for current to energize the "safe" mode?

 

I checked a diagram with a 4.9 and the feedack carb system, and I believe you are correct. The EEC relay powers the computer, carb solenoid, purge canister valves, tad, tab and egr valves. The TFI ignition module is fed power separately, so the module must still fire the coil in a "locked timing" type mode, and the carb must not need the feedback solenoid to feed the engine enough fuel to run.

Thanks for that info.

 

The feedback solenoid on the carb (4.9 eng) is normally rich and goes really lean when it is energized. I hooked up a push button switch and manually energized it while watching the output of the O2 sensor. This testing was done in an attempt to improve MPG while still using a feedback carb with a Duraspark distributor.
<O</O
During 3-4 months of manually energizing the feedback solenoid to drive it lean I could not tell any significant difference in MPG and thus I am just going to keep using the feedback carb.
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I did have to use the push button switch to pass emissions, 25-35 MPH with the back wheels on load drums. It does run rich at 35 MPH based on the O2 sensor but the fuel flow is pretty low as it at 1600 RPM anyway. The second emission test was done with the C6 in 2nd gear, per the emissions tester request, not sure why.
At freeway speeds, over 55 or so, it goes lean anyway as the carb seems to be giving it all the fuel it can.

 

Thanks, guys, for your feedback on the "FEEDBACK" system!!!

It speaks well of our trucks than an original electrical component has lasted 26+ years.