A new question is answered every 9 seconds

1994 Ford Ranger 4x4: 4L engine v6 xlt: My truck dies..freeway

This answer was rated:

Disabled Veteran needs work truck to run again...I have a 1994 Ford Ranger 4x4 4L engine v6 xlt: My truck dies suddenly at random times with no warnings. It happens at an idle sometimes and on the freeway other times. The truck runs fine otherwise but this problem happens more and more randomly. Sometimes it will start up again but other times it wont start for a day or two then will fire right up??? I got the diagnostic code 543 secondary fuel pump circuit fault... What does this mean? How do I fix it , what do I need or what should I replace? The fuel pump does come on and I changed the fuel pump relay and it worked for a week or so then it started happening again. Please help me, Thank you so much.

Hi thank you for your question hope this helps.


Diagnostic Trouble Code (DTC) 543 indicates a fuel pump secondary circuit failure between the B(+) supply and the Fuel Pump Monitor (FPM) connection to the power-to-pump circuit. 99 times out of 100, this DTC results in a no-start condition.


If the engine starts and runs, the it is a pretty good indication there is a problem with the Power train Control Module (PCM).


NOTE: Due to the internal circuitry of the Power train Control Module (PCM), a left/front Heated Oxygen Sensor (HO2S) signal short to power could produce a Diagnostic Trouble Code (DTC) 542 or 543. So be for replacing the PCM replace the Front Drivers side 02 sensor. But with your no start and engine stalling i am thinking PCM failure.


Hope this helps

Good luck

david, Auto Service Technician
Category: Ford
Satisfied Customers: 1500
Experience: Certified Master Technician,Certified in diesel & gasoline engines
david and 6 other Ford Specialists are ready to help you
Customer: replied 7 years ago.
Do you think getting a PCM from a junk yard would be okay? Is there any way to test the PCM? Could I take my PCM to a Ford dealership to have it tested? The bottom nut on the PCM looks tough to get on and off, any tricks? Thank you for your help.

First a junk yard PCM is a crap shoot you wont to look for one that is not from a truck that has been in a reck. Yes the a ford dealership can test the PCM.


My trick for getting the bottom nut is 1/4 inch ratchet and a long extension.


To remove

  1. Disconnect the negative battery cable.
  2. Disengage the wiring harness connector from the PCM by loosening the connector retaining bolt, then pulling the connector from the module.
  3. Remove the two nuts and the PCM cover.
  4. Remove the PCM from the bracket by pulling the unit outward.


To install:

  1. Install the PCM in the mounting bracket.
  2. Install the PCM cover and tighten the two nuts.
  3. Attach the wiring harness connector to the module, then tighten the connector retaining bolt.
  4. Connect the negative battery cable.



Customer: replied 7 years ago.
Is it possible for it to be the Ignition Control Modual? Or could it be a groud?

i would not thing a ground would give this problem because in this case the battery power is not getting to the fuel pump circuit witch is feed throw the PCM. but you could give it a try stranger things have happened.


As for the ICM you would have different problem's along with Diagnostic codes. something along the lines of bad communication codes or faulty communication codes


Ask david Your Own Question
david, Auto Service Technician
Category: Ford
Satisfied Customers: 1500
Experience:  Certified Master Technician,Certified in diesel & gasoline engines
Type Your Ford Question Here...
david is online now
How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

What Customers are Saying:

  • AlvinC answered a question about my Ford truck that only someone with an in-depth knowledge of his subject would have known what was going on. Rich D USA
< Previous | Next >
  • AlvinC answered a question about my Ford truck that only someone with an in-depth knowledge of his subject would have known what was going on. Rich D USA
  • Because of your expertise, you armed me with enough ammunition to win the battle with the dealer. They are installing a fuel filter and fuel pump at no charge to me. Molly USA
  • I needed help with my car on Saturday morning....got a response in 5 minutes, and it was the perfect solution. Thanks again to your service. Jason V. Kirkland, WA
  • I do know, after going though this with JustAnswer, that I can somewhat trust my mechanic but I will always contact you prior to going there. BR New Jersey
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

Meet The Experts:

  • Ron


    ASE Certified Technician

    Satisfied Customers:

    23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
< Last | Next >
  • http://ww2.justanswer.com/uploads/FO/fordguyu/2015-7-7_172556_onnieew.64x64.jpg Ron's Avatar


    ASE Certified Technician

    Satisfied Customers:

    23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka- Moose)'s Avatar

    Chris (aka- Moose)


    Satisfied Customers:

    16 years experience
  • http://ww2.justanswer.com/uploads/JM/jmcdo28/2012-2-23_01655_resized.64x64.jpg John Mc's Avatar

    John Mc

    Ford Technician

    Satisfied Customers:

    19 years Ford Lincoln Mercury experience
  • http://ww2.justanswer.com/uploads/wmarti7/2009-4-18_04332_Avatar.jpg Chuck's Avatar


    ASE Certified Technician

    Satisfied Customers:

    33 Years Experience,Ford Senior Master,ASE Master,L1 Advanced Engine Performance
  • http://ww2.justanswer.com/uploads/BL/Bluegorilla/2012-6-21_16298_cam.64x64.JPG Cam's Avatar


    Journeyman Automotive Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years Automotive experience.
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar


    ASE Certified Technician

    Satisfied Customers:

    12 years at a Ford Lincoln/Mercury and Jaguar dealer as a technician and shop foreman.
  • http://ww2.justanswer.com/uploads/BA/baddad1/2014-4-1_23659_avatar.64x64.jpg Mike V.'s Avatar

    Mike V.

    Auto Service Technician

    Satisfied Customers:

    25 years experience on all makes and models, Licensed NYS Inspector.