Ford EEC-IV Test Procedure


Old 04-14-06, 06:54 PM
Thread Starter
Join Date: Mar 2006
Posts: 7
Ford EEC-IV Test Procedure

I would like to perform the KOEO, KOER, and Cylinder Balance tests on my 1993 Ford Explorer (4.0L 2WD 235K). Chilton says it has an EEC-IV system.

Does anyone know if the test procedure to flash the CEL, as described in the following Mustang website, also applies to my Explorer?

If so, can anyone tell me where the EEC-IV test connectors are located in a 93 Explorer?

Thanks much.
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Old 04-16-06, 07:01 AM
Join Date: Aug 2003
Location: Cape Cod
Posts: 4,320
The procedure to "pull" or retrieve the codes is the same for all EEC-IV computers

I'm sure the Corral has the proper test posted
I tend to link people to this one

"Flashing" the computer refers to actually changing the programing

Older trucks are usually on the RH fender apron, though Broncos it's near the starter

By '93 it may have been moved to the driver's footwell
Not sure on that

Please don't hesitate to post up any codes for interpretation
(ex: an "o2 sensor reads lean" code does not mean to replace the o2 sensor)
Old 04-17-06, 08:07 AM
Join Date: Sep 2004
Posts: 238
Balance test

From the cited web pages you see what the connectors look like. Just look for them. On a '94 taurus they are on the pass. side firewall.

I use the jumper wire and cel flashes. The volt meter was too hard for me to read. Be patient and repeat a couple times. You may get a random flash at the beginning that none of the procedures tell you about, just relax.

to get the balance test on the taurus after the KOER codes display without turning-off the car or removing the jumper wire, depress and release the gas. The car will go into the balance test. You will hear the motor slow down as it kills spark (or gas?) to one cyl. at a time.

It will go through 3 cycles and after each will flash cyl nos. for weak ones or 9 for ok (at least balanced) on all 6 or 77 for aborted test (if you hit the gas again or the jumper wire fell off).

good luck
Old 04-19-06, 06:49 PM
Thread Starter
Join Date: Mar 2006
Posts: 7
Thank you both for the info. I will try to run the tests this weekend.
Old 04-25-06, 06:16 PM
Join Date: Apr 2006
Posts: 2
Originally Posted by cclshome
.....If so, can anyone tell me where the EEC-IV test connectors are located in a 93 Explorer?

Thanks much.
On my '94 explorer, the connectors are attached low and to the rear of the power distribution / fuse box next to the passenger side front wheel well.. it's facing up but has a clip-on cover that sorta disguises it. it's attached to the fuse box by a single expanding plastic rivet. Pop it off ( it will press back on later) so you can remove the cover.

I found your post because I was looking for help for myself.

My explorer failed smog.. High NOx at low rpm only. Using the analog volt meter method returned the following trouble codes
in KOEO mode
335 EGR feedback signal is out of range
558 EGR vacuum regulator circuit failure
and then in memory
536 Brake on/off switch not activated during self test

any advice would be appreciated..
Old 04-26-06, 09:05 AM
Join Date: Sep 2004
Posts: 238

I don't know about your specific set-up since I was working on a Taurus when I figured-out how to read these codes.

And since it is a slow day at work….

When you start the KOER codes you should stamp on the brakes several times while moving the steering from left to right extremes several times and if you have an od switch you are to hit that a few times-I don't so I never did that. Stop and then wait until you get a single light flash then hit the gas hard one time. These tests check out the power steering pressure switch (so the engine won't die at idle), brake switch( I believe this drops the cruise control), OD (?), and throttle position sensor.

Again, I will say counting CEL flashes is easier. Your assistant will verify that the light flashes with your VOM needle sweeps and you get to sit down while doing it.

I paid Expressway Ford in El Paso $70 for advice and then went to Auto Zone and bought the parts Ford said I needed for about 30% of the Ford parts and labor cost. One part was only available from Ford, a vacuum regulation valve. After spending about $210, I was still stuck. None of the parts helped, and the originals where still good.

The egr port in the intake was plugged. Start your car and listen to it idle remember how it sounds you should have no egr at idle if you have a smooth normal idle. Hook up a vacuum pump to the egr valve and apply vacuum. If the vacuum hold you egr valve is probably good. If your idle goes to crap your valve IS good and your EGR passages are not blocked.

You don’t have a vacuum pump? Take the egr valve off the car and try to start it. You should have a super vacuum leak. It should not idle or idle only poorly. If does idle poorly, plug the port with your finger and the idle should smooth out.

If this does not help write back. Be sure to ckeck the simple stuff first (all wires and hoses connected and in good shape).

All I needed to do was remove the upper intake manifold (plenum to some people) and clean out the passage. Total cost should have been 2 cans of gumout and a new gasket for a total of $12. I took me a while to figure it out. I was just like the Ford techs and wanted to replace parts named in the codes. I should have known better, since the car had been knocking like a big dog for a while.

I wondered what the dealer would have done If I gave them the green light for $600 worth of work.
A. Call and say the screwed up and only the passage was blocked and charge me one hour labor to clean it
B. Call and say I needed additional work once they realized new parts did not fix the problem.
C. Do the additional work once they dicovered the actual problem and stick with the original quote and not say anything.
Old 05-01-06, 04:11 PM
Join Date: Apr 2006
Posts: 2
re: egr

thanks peabees for the input. I tried the vacuum tests and the EGR valve checked out OK. Turns out the problem was the egr pressure sensor ( all fords have this sequence of the part# in common: 9J460 ) Mine was supposed to give ~ 0.5 volt between grnd and send when cold ...going up to ~ 5 volts when hot. Mine was 2 volts with just key on ..and never changed. I changed it out with a autozone aftermarket part ($42) and it passed smog with flyin colors.. :-)

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