All is not well...I only thought I had things back on the right track...now I am having some additional problems including...1) cel that stays on most of the time,except when coasting downhill 2) my truck cuts off nearly every stop, especially on hard stops...it starts right back up...3)the knocking and pinging is severe at times and the loss of power is there as well...I'm now thinking that with 179k miles, it might have some bigger issues...I don't suppose Autozone or Advance checks engines lights for 94 models, do they...need some help guys

 

1. Check your codes. Buy a Haynes manual, read it, buy a multimeter (analog with the needle), pull codes, come back to us with code numbers for further assistance.

2. See above.

3. Might be related to 2.

Otherwise, without knowing which engine you have, it's tough to even fathom a fruitless guess (that's what the CE light is for anyway) about what's going on.

 

Advance & AZ in my area use the Actron CP9150 scanner kit , which has the connector cables to scan it. So call around & check to see which scanner is used in your area, if you don't want to pul the codes yourself. Then post ALL the codes you find.

 

You can pull the codes yourself with a simple jumper wire (even a paper clip will do) and by counting the number of CEL flashes.

Find the EEC Test connectors under the hood of your Ranger and then follow these instructions for pulling codes on a Ford EEC-IV (pre '96) vehicle:

Pulling Ford EEC-IV Trouble Codes

Report back with the codes.

 

I was able to get the following codes...this is on a 94 4.0 v-6 auto with a/c and 179k,,,cel stays on most of time now...
1) 539 ac on during self test
2) 542 fuel pump circuit open
3) 571
4) 581
5) 167 insufficient throttle position
6) 411 unable to control rpm during low rpm self test

Please advise

 

I was able to get the following codes...this is on a 94 4.0 v-6 auto with a/c and 179k,,,cel stays on most of time now...
1) 539 ac on during self test
2) 542 fuel pump circuit open
3) 571
4) 581
5) 167 insufficient throttle position
6) 411 unable to control rpm during low rpm self test

Please advise

 

Here's how the codes come up:

539 - AC on/Defrost on during KOEO
542 - Fuel pump secondary circuit fault
571 - no such code
581 - an electronic cooling fan fault code
167 - Throttle Position sensor fault during dynamic response test
411 - R Cannot control RPM during KOER low RPM check

The 539 code is set when the self-test was not run properly;

The 542 code could incicate a bad fuel pump/and or fuel pump circuit, but sometimes this code is set when there is a stall while in gear (at least on some Fords);

The 571 code doesn't exist; again, could be the self-test was not run properly

The 581 code is not applicable, since your 4.0L doesn't have an electric cooling fan;

Code 167 is often the result of the self-test not being run properly;

Code 411 also is often the result of the self-test not being run properly
In short, it appears that maybe you didn't pull the codes properly. However, don't be discouraged by that, since it is kinda hard at first for everyone but it gets reqal easy after you do it a few times.

I recommend that you remove the negative battery cable for 20 minutes in order to erase the computers meory (and the codes). Then after you drive around for a while, maybe even a few days, try pulling the codes again. This will insure that any codes that you do pull are not "stale" (i.e., left over from a concern that no longer exists).

You might even try Autozone, see if they will pull the codes on your '94 a with a scanner for you. Or, EEC-IV scanners are like $30 bucks these days, pretty cheap.

 

I really appreciate the follow up...I will do you as you suggested and try to pull the codes at another time to see what might be the real problem...I still have the truck cutting off at some red lights and occasionally while driving while not accelerating...the only thing that I have done recently was to change the pcv valVe, change a worn belt, and change the transmission fluid and filter...the cel did not come on for about a week after that...I'll check with you guys later

 

OK then...I picked up actron Code Scanner as you suggested and got the following KOEO Code...542...I remember what you said that might cause this code...my truck stalls nearly every time I stop now...the next section indicated the Continuous Memory Codes...157, 158, 172, 176, and 542(again)...In this section, the directions suggested fixing the "hard" code or codes before moving onto the next section...the reference section indicaed a Fuel Pump circuit open connection...Please make any suggestions...should I go onto the next section...KOER...?

 

You need to fix codes beginning with KOEO, then KOER, and finally CM. Sometimes, for example, fixing a KOEO codes eliminates a KOER or a CM code. Ignore all KOER and CM codes until your KOEO faults are corrected.

 

I was doing some research and found a thread you and another user, moat, started back on August 5. 2005....It looked like you had 157 and 158 codes and you replaced the iac AND IT WORKED 100%...THE OTHER GUY, MOAT, REPLACED THE maf AND IT WORKED FOR HIM...do you think the 542 code is a valid code needing repair or do you think it is the 157 or 158 that is the problem...?

 

Acording to the info on my CD, DTC's should be addressed in the numerical order received. Since 542 is your only KOEO code/DTC (right??), that needs attention first. Address the KOEO code first; ignore KOER and CM codes until you have code 111 on KOEO. For the 542 KOEO, you should verify that when the key is on and the engine is not started, that the FP stops buzzing after a few seconds. This is a start. I wished I could cut/paste info from that CD here .

 

Joe, the 542 code could cause the 157, 158, 172 & 176 codes as the engine stalls. So as Bill suggested it should be addressed first!!!!

As the 542 code is for a open circuit between the PCM & engine, I'd check that pesky fuel pump relay & see if it's acting up.

Maybe swap it for another like one, in the under hood power distribution box & see how things go.
If that fixes things up, replacethe relay, they can be had for about $5 at most autoparts stores.

They are such a common failure point, many Ford folks are now carrying a spare in the glove box with the fuses LOL.

Just some more thoughts tossed into the fray.

 

Yes, listen to Bill and pawpaw with regard to addressing the codes in proper sequence. I may have given the impression in my earlier post that the 542 code is always a result of a stall, but that is not the case. A 542 code can inciate a legitimate problem with the fuel pump/circuit. So you should start your diagnosis there. Even if you at least rule out the fuel pump/circuit as the cause, that will help with the rest of the troubleshooting.

Here's what the Ford Manual says:

A Continuous Memory DTC 542 indicates that one of the following intermittent conditions has occurred:

-- Fuel pump circuit activated when PCM expected circuit to be off (i.e., fuel system test or prime procedure).

-- Inertia fuel shutoff switch reset (if in power-to-pump circuit).

-- Open circuit in or between the fuel pump and FPM circuit at the PCM

-- Poor fuel pump ground.

-- FPM or power-to-pump circuit short to power.

-- Fuel pump relay contacts stuck closed.

-- Left/Front HO2S circuit short to power (with/dual HO2S).

-- Engine stall due to excessive load.

* * ** ** ** ** **
Start engine. Check for engine stall/stumble while performing the following (also, if possible, listen for fuel pump turning off):

-- Shake, wiggle, bend the power-to-pump circuit between the power-to-pump pin at the fuel pump relay and the fuel pump.

-- Shake, wiggle, bend the fuel pump ground circuit from the fuel pump to ground.

-- Lightly tap the fuel pump to simulate road shock.

-- For vehicles with the Inertia Fuel Shutoff switch in the power-to-pump circuit, lightly tap Inertia Fuel Shutoff switch to simulate road shock.

 

So...back at it again...I was doing some research and found where someone replaced the IAC sensor and solved the problem...I checked the voltage which is good...checked the resistance at RX10 and got a reading of 1...now is that a total of 10ohms...?...if it is, Haynes indicates it is a good resistance...changed the fuel filter and added Valvoline injector cleaner...seemed to help and got cel on somtimes and not on sometimes...today, cel came back on and stayed on......knocking and pinging still there...not there when I bought the truck back in 2002...is there a knock sensor in this baby...?...tried all the recommendations made by this forum including decarbon......please help