Notes on pulling EEC-IV codes | Page 2 | Ford Explorer Forums - Serious Explorations

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Notes on pulling EEC-IV codes

Changing out the DPFE sensor did the trick! Thanks for the Help!!

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should i do nothing about the code 632? or should i perform koeo again, this time remembering to push the button. Could it possibly show new codes , that it didnt before?

I would not expect to show different codes, but I would do it again, anyway. If for no other reason than it is good practice.


Yeah, what the heck, I'll do it again. I like learning new stuff everyday.

I don't know if yet another video is really needed, but this guy, in post #3, posts another video reading his codes (I hope future JP doesn't mind). This set has a long list of KOEO codes, but passes CM. If you can read this set of codes, you should be able to figure out just about any list your PCM can spit out at you.

Mr Shorty,

amazing post. to think i was trying to figure out if the MAF is messed up or i fouled my plugs and am having a misfire without doing it the old fashioned way. Thank you.

I guess mainly i have a follow up situation I would enjoy your input on:

Firstly its a 1st Gen 93EB with 85K original miles on it. I got it with 57K almost 3 years ago, but before me it sat and sat, then was driven again until my buddys father passed in 2008, then it sat again until i bought it. rust, isnt even the word for this baby, but she runs like a top most times. sorry to digress.

So, the CEL has been coming on an off for a bit now, and I believe i have many codes stored within the brain of the EEC. So my question is this: after doing some minor work to her (plugs, wires, total brake lines, fuel lines done by a pro (mostly) and myself (the easy stuff)), would it be a good idea to try and regenerate the codes after clearing or resetting the last batch or read these current codes??

i know i know... do both, gain which i will end up doing,, but my fear is that there are a lot of codes that are now cleared by the work we have done, and perhaps a few more that we created by shoring up other parts of the truck.

thanks for any thoughts you may have on this and for all the work you put in.
this site is great

A couple of thoughts:

1) It is certainly possible to create extraneous CM codes especially if, while doing that work, you started the engine while something was unplugged. You won't know what CM codes are still meaningful until you clear CM and take it for a test drive.

2) KOEO and KOER codes are not stored in any way. They are "hard faults" that are detected during the test. If you run the tests and get any codes for these portions, you know that there is something related to that code that is still wrong without going through the clear memory and test drive sequence.

great, so that saves me a step. I did happen to turn it over and have not turned it on yet since, after reading not to until you are ready for KOEO, then KOER.

Thanks again and hope you are having a great day! i will be sure and share the codes and anything peculiar that happens in case someone else is having some similar problems.

could only complete the KOEO test which produced codes 181 186 189 which i believe is a too rich gas supply that either fouled my plugs or gunked up my fuel pump. the KOER test could not complete as it would stall the engine i believe because it tries to begin tests on the fuel pump or something fuel related. best idea i have would be to replace or clean the plugs, try and test drive and see if i can get other codes.

if anyone has any ideas or a link to another post that may help, it would be much appreciated...thanks

My code list indicates that each of those codes is from the O2 sensor having indicated a lean condition. If the engine is actually running rich, then that suggests something wrong with the O2 sensor/circuit. If it really is running lean, then something else is throwing off the mixture.

Thank you for this MrShorty! Much better explained than Haynes ever did!

hey guys,

picked up a 1992 for trade a week or so ago and i noticed the check engine light is not coming on, couldnt pull codes (i got the fp to prime, and a few relays to click.) but the comp was not communicating with my code reader. I tried the paper clip trick, no change.

did some research and i just ran a jumper from the +batt to the number 4 pin on the self-test plug (pink/green and tan/red) and the light switched on, but is still not communtiating...

any ideas? i cant get a hold of a good wiring book for the explorer (i had one for my 88 full size bronco but i seem to have misplaced it.


edit: the motor runs really well, i just want to make sure everything is working well for smog and what-not

Power and ground to the PCM?

that's what i was thinking but i dont have a diagram of the PCM plug, i work for ford but the troubleshooting and wiring book is on back order and that could take years literally. can someone shoot me some wiring diags on pdf?

Check the keep alive memory wiring & ground wire near the battery. This once happened to my 88 van. The van wouldn't start. There was no check engine light, and the fuel pump wouldn't prime. It's also a good idea to check the PCM relay. The fuel pump relay can't work if the PCM relay doesn't work (unless it's grounded through the self test such as what you've already done). It sounds like you provided power through the seft test connector as well.

I've found that the wiring diagrams in Chiltons are adequate for PCM power and ground circuits. Autozone has electronic versions of the Chilton's DIY manuals on their website (if you are willing to register with them).

I've also found that most public libraries have good manuals you can pull wiring diagrams from.

ok cool. ive got power to the fuel pump and the explorer runs really well, just not able to pull codes. in CA they check the light to make sure its working (guess you cant have a check engine light on when you go smog or it will fail iirc) and i dont know how they get the light to flash. if i knew that they just put power to that 4th pin to check id be in good shape but i dont want to waste ~$50 when i go smog it

I have a eec relay from my FS bko and i swapped with both the eec and the fp and nothing changes

The engine would not run if the PMC didn't have power. If the only problem seems to be that you can't pull codes, I'd check your instructions and make sure you are doing it right and making good connections with your jumper wires. You might also check the wiring between the self-test connector and the PCM to make sure there are no bad connections.

made some photo copies of the eec wiring and the pcm plug.

pin #4 has pink/light green AND tan/red leads into it connected at one spade connector inside the self test connector...

pk/lg is circuit 658 (to pin #17 at the pcm)
t/r is circuit 201 (to instrument cluster, "check engine light")

from hooking power directly from the battery to plug #4 on self test connector, the check engine light comes on with or without the ignition on, so i know circuit 201 (to check engine light) is good. i just need to get to the #17 pin on the pcm plug to test continuity from the self test plug to pin #17 on the pcm.

if that circuit is good, check resistance, of that is close to zero then i need to inspect the actual connection into the pcm to see if that is the problem.

dont really have time tonight but i will dig into it tomorrow when i get off work.

sucks cause the same wiring book we use at work are on back order and like i said, could take a very very long time to get in... im trying to convince our parts guy that the 4 inch thick body/frame/suspension/drivetrain book we have at the shop need to be replaced... its been in "the attic" for god knows how long and the cover is missing... he said the shop cant get them anymore from ford.. i told him hes just being lazy lol.

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Everything seems on the up n up with that circuit. So I'm kinda confused as to what the problem is now.

Circuit 658 has continuity the system just isn't pulling up the codes. Checked the volts at pin four on the self test connector and it's pulling about 0.54v. Iirc that's not even ref volts, shouldn't it be around 5v?