I started my truck to warm up for work. When I came out to go to work the truck wasn't running. Have no spark, there is power to the coil just no signal. Also no fuel pressure. I checked all the fuses and checked the operation of the relays and there 12v supply and 12v trigger, everything is working. I can't find the EEC relay. What is EEC, and what is it's function?

 

1. EEC= Electronic Engine Control. EEC relay powers up the computer, and in Mustangs, at least, around early 90's it was located behind the RH kick panel in the car, along with the computer. Not sure about location in truck, sorry.

2. You DO know the fuel pump is turned "on" by the computer, right? And that it only runs 2 seconds when the key is turned to "ignition on", not all the way to "start" position?

3. If EEC relay is bad, there will be no spark, and no fuel pump operation.

 

From our buddy Bill:



That is a photo of the engine compartment fuse panel.

PCM is the acronym for the Powertrain Control Module. Some documentation also refer to it as the EEC relay.

 

thank you. so you are telling me that the EEC is the same as the PCM? Then it is most likely my engine computer.

 

Maybe but if you think so just unplug the PCM Computer and see if spark returns.

If spark does not return then it is NOT the PCM Computer.

If spark does return it is more than likely your problem. But in this case make sure the computer has a good ground on pin #40 & #60 and power on pins #1, #37 & #57 with the key on before you say it is bad.

Some say you can just unplug the SPOUT in stead of the Computer but you know it is out of the loop if you unplug it.

EEC: Electronic Engine Control. The system that provides electronic control of engine operation. Your system is call EEC-IV.

PCM: Powertrain Control Module. The module that controls the EEC system. Sometimes called the Computer or ECU.

 

Ok thank you for the info. I will check that out. I believe the PCM is located in the drivers side kick panel behind the bracket with the hood release lever. can someone verify that's the pcm, or ecu? You all have been so helpful, this forum is the only reliable source of info i have found since the truck stopped running, thanks again!

 

Yes that is the PCM Computer (AKA ECU) but it has to come out from under the hood.
You will have to take the inter fender loose and pry it apart with a broom handle and pull it out through the gap.

But you do not have to remove it to unplug its plug with the 10mm bolt in it for the spark test.



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so that is the longer skinnier harness connecter closer to the drivers door on the fire wall?

If the eec is not the pcm, where can i find the eec relay? It's not in the fuse box.

also is there an eec test i can do without having a diag comp

 

is the EEC the ignition module mounted on the driverside inner fender with the heat sink?

 

Look at my post #5 above.

The EEC is the type of system, yours is a EEC-IV (4).
The EEC-IV uses a computer (PCM, Powertrain Control Module), Ignition Control Module (ICM and it is a type TFI).
This EEC-IV system uses computers, relays, solenoids, sensors and fuel injectors.

 

I got ya. I'm in tune now. Thank you so much for all the info. will let you know what i find out with the tests on the PCM power and ground supplies and if i get spark back when it's unplugged.

 

Be careful with that 10mm bolt head.
I may be the only one who had this problem but mine turned 1/4 turn and spun forever.

The insert that it threads into had broken loose inside the computer and it literally took me weeks of (s)praying and prying to get the 60 pin plug out without shattering it to pieces.

There are about 7 or 8 threads on that bolt so it should weasel that connector out about 1/2 inch.

That bolt itself will draw the plug apart as you loosen it and will draw it back in as well.

Some say dielectric grease is best for the connections and
electrical computer type contact cleaner (NOT electric motor cleaner) and make sure it goes in straight and go very easily.

You may want to mark the position of the connector with a magicmarker so you know how deep it wants to go when you put it back together...and so you don't overtighten it.

It will squeeze onto a thin rubber gasket thing. and that's IT!

Don't mean to freak you out but mine was ^%^&* to get apart.

Get some good light, something stable to stand on and I actually threw a beach towel under the hood to lay the computer on like a surgical work area.

Then again, yours might come out and go back in with NO problem like everyone else in the world but me.

I kinda wonder why that underhood rubber water diverter stops just before the hood hinge and lets water run right down on that computer connection, but that's just me.

You'll be so happy when it's all a distant memory and worth every minute of 'creative' solutions.

 

Well thankfully i didn't have a problem with th connector bolt.

I checked for voltage and ground at the connector, everything checked out good, and I have spark when the connector is unplugged.

is there any other tests that I can do to rule everything out. There are 9 different PCM's that it could be. and I'm pretty sure you can't return them if you use it.

I'm thinking everything is pointing to the PCM though. thanks again every one. I'll let you know what the new PCM does. It might be a day or so.

 

You can open up the Computer and see if anything is burnt or if any Caps are loose.
You can take the number off the computer plug and match that with the new one to get the right one.
If the number is missing off the plug it is a rebuilt computer. So in this case take the Calibration Number off the drivers door and post it and we will look up the right computer number for you.

 

I had a similar problem on my '87 i6 4.2l that left the truck in the yard for about 8 months. Slammed my hand down on the fender inside the hood after hooking up the battery again one day and heard a fizzle noise. Took apart some tape on the yellow wires and found a factory solder joint that was absolutely corroded. Cleaned and re-soldered it and it's been great ever since. Found another joint closer to the firewall and fixed that one as well. Not sure if they continued this type of solder work on the '92s, but it's worth looking for since it will rot out eventually.