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On a 1998 expedition, where is the pcm and the ecm--5.4 litre

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  • marqsil Dec 20, 2010

    the car not run



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  • Ford Master
  • 17,970 Answers

1998 Ford Truck Expedition 4WD 5.4L EFI 8cyl

PCM Ford's Location:
* Ranger - behind instrument panel (cowl), center to both driver and passenger sides.
* Explorer/Mountaineer - behind instrument panel (cowl), (access from engine compartment dash panel) on passenger side to center of vehicle.
* All other F-Series, Expedition/Navigator - lower dash panel on passenger side.
* Excursion - lower dash panel on driver side.

The PCM is behind the glove box and has a big harness connector in the firewall that you access from the engine compartment.


on a 1998 expedition, where - a927c58.jpg

Fig. 1 The calibration number will be needed to order such parts as a replacement PCM, various sensors, and almost any emission control component. Typically this number is attached to a label found on the driver's door or the door pillar

1997-00 F-150, F-250, Expedition and Navigator


Fig. 2 Loosen the connector retaining bolt and remove the PCM connector

Fig. 3 Remove the passenger side front door scuff plate


Fig. 4 Remove the passenger side kick panel


Fig. 5 Remove the PCM bracket clip and remove the PCM

  1. Remove the battery and the battery tray.
  2. Loosen the connector retaining bolt and remove the PCM connector.
  3. Remove the passenger side front door scuff plate.
  4. Remove the passenger side kick panel.
  5. Remove the PCM bracket clip.
  6. Remove the PCM.
To install:
  1. Installation is the reverse of removal.
  2. Tighten the PCM connector retaining bolt to 36-44 inch lbs. (4-5 Nm).

Hope helps.

Posted on Jul 13, 2010

  • 8 more comments 
  • Conrad Deane
    Conrad Deane Jul 13, 2010

    thank you, that was absolutely the best explaination i've had so far. is it possible for you to review prior questions,or do i need to resubmit to you a question on misfires for this vehicle?

  • Conrad Deane
    Conrad Deane Jul 13, 2010

    also looks like calibration tag missing--now what can i do?

  • ZJ Limited
    ZJ Limited Jul 13, 2010

    DTC P0300 - Random/Multiple Cylinder Misfire Detected

    What does that mean? Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.

    A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

    Symptoms may include:
    * the engine may be harder to start
    * the engine may stumble / stumble, and/or hesitate
    * other symptoms may also be present

    A code P0300 may mean that one or more of the following has happened:
    * Faulty spark plugs or wires
    * Faulty coil (pack)
    * Faulty oxygen sensor(s)
    * Faulty fuel injector(s)
    * Burned exhaust valve
    * Faulty catalytic converter(s)
    * Stuck/blocked EGR valve / passages
    * Faulty camshaft position sensor
    * Defective computer

    Possible Solutions:
    If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

    If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

    Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

    About your second question, "calibration" subject, I suggest search for this bulletins:
    - TSB 04-21-14 refers to "Hesitation during accel and/or erratic idle
    coming to a stop"
    - TSB 05-05-15 refers to "Rough Idle - 5.4L and 4.6L"

    Hpe helps.

  • Conrad Deane
    Conrad Deane Jul 13, 2010

    changed all 8 plugs on a 1998 expecition, then misfires started under load, none supposedly prior. changed all coils, reinspected plugs for damage,crackes etc-changed some again- no codes during first week of reinspection, then p0301 occurred. changed injector, still missing,now p1401,p0307,p0300 started to show up. idles fine, intermitent misfire driving, brake torqueing, flashing fast ses light on ex way. please help

  • Conrad Deane
    Conrad Deane Jul 13, 2010

    Jul 10, 2010 - any ecm injector driver concerns on 1998 ford expedition

    Jul 10, 2010 - p0305 and p0307 constanly returns even after swapping good parts from known good cylinders to misfiring cylindrs. pcm concern?

    Jul 13, 2010 - where is the pcm and the ecm for a 1998 expedition,5.4 litre--i was told the ecm would be the problem with possibly an injector driver/quad driver. i think if any module it would be the pcm-powrtrain control module and not the ecm???

  • Conrad Deane
    Conrad Deane Jul 13, 2010

    As you know all codes exept p1401 are reporting random misfiring. The p1401 refers to too high voltage in EGR circuit. This code may also be related or caused by the misfiring.or by a faulty ECM. As you can tell, i'm sending you the many answers i got ,all referring to ecm,pcm,wires(which they don't have)- etc. could you please simplify all these answers to my questions originally asked?? i work for cadillac and the ecm and pcm are the same, just called differently at times and by whomever is explaining their concerns! so when experts are telling me the ecm is the problem and/or the pcm is differnt and that is the problem,i am getting very confused- i think the pcm is causing the intermitent loss of driver to injectors.

  • Conrad Deane
    Conrad Deane Jul 13, 2010

    unable to locate and pull up either tsb. no number in ford website for tsb's- missing it somewhere

  • ZJ Limited
    ZJ Limited Jul 14, 2010

    This worng just report to the PCM; for the EGR fault, I suggest check this definition about the EGR Valve and System - it's just three letters,
    but EGR can result in AGGravation.

    Common in automobile emission systems since the early 1970s, the EGR
    Gas Recirculation) valve controls an engine’s emission of smog-causing

    nitrous oxides, or NOx. Its job is to route a portion of the exhaust
    gases back
    into the intake manifold. That lowers combustion temperature to below
    degrees Fahrenheit – the temperature at which NOx gases form.

    EGR flow is controlled by the engine’s computer, which opens or
    the valve as needed. The EGR system is, for the most part, in the “out

    of sight, out of mind” category, and typical doesn’t require regular
    maintenance. But if it gets clogged with carbon deposits, you’ll see
    “check engine” light come on, and a code (perhaps P0401
    or P0402 or P0403) will show that
    there is insufficient flow. That typically results from a vehicle
    being driven
    persistently on short trips that don’t allow the engine to fully warm
    up. Flow problems also can be caused by carbon buildup due to failure
    to change
    the oil frequently enough.

    A clogged EGR valve not only results in higher emissions, it can
    affect fuel
    economy and cause rough idling – even serious engine damage. Valves
    usually be cleaned, but replacement is often recommended.

    Advice? Make sure to put on some highway or freeway miles, and always
    the oil according to the maintenance schedule in your owner’s manual.

    DTC P0401 - Insufficient EGR Flow
    What does that mean? EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

    Symptoms: You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.

    Causes: A code P0401 most likely means one or more of the following has happened:
    * The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
    * There is a blockage in the EGR (tube), most likely carbon buildup
    * The EGR valve is faulty
    * The EGR valve may not be opening due to a lack of vaccuum

    Possible Solutions:
    In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
    * Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
    * Clean out the EGR valve and/or tubing to remove deposits
    * Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
    * Replace the DPFE sensor (with a good quality / OEM one)
    * Replace the EGR valve

    Related EGR Articles: P0400 - P0402 - P0403


  • ZJ Limited
    ZJ Limited Jul 14, 2010


    Fig. 1 Differential pressure feedback EGR system schematic (click for zoom)

    The Exhaust Gas Recirculation (EGR) system is designed to
    reintroduce exhaust gas into the combustion chambers, thereby lowering
    combustion temperatures and reducing the formation of Oxides of Nitrogen

    The amount of exhaust gas that is reintroduced into the
    combustion cycle is determined by several factors, such as: engine
    speed, engine vacuum, exhaust system backpressure, coolant temperature,
    throttle position. All EGR valves are vacuum operated. The EGR vacuum
    diagram for your particular vehicle is displayed on the Vehicle Emission
    Control Information (VECI) label.
    The EGR system is Differential
    Pressure Feedback EGR (DPFE) system, controlled by the Powertrain
    Control Module (PCM) and composed of the following components: DPFE
    sensor (also referred to as the backpressure transducer), EGR Vacuum
    Regulator (EVR) solenoid, EGR valve, and assorted hoses.

    DPFE Sensor

    1. Disconnect the pressure hoses at the DPFE sensor.

    2. Connect a hand vacuum pump to the downstream pickup
      on the sensor.

    3. Using a multimeter, backprobe the SIG RTN circuit at the DPFE

    4. With the ignition
      , signal voltage should be 0.20-0.70 volts.

    5. Apply 8-9 in. Hg of vacuum to the sensor. Voltage should be
      greater than 4 volts.

    6. Quickly release the vacuum from the sensor. Voltage should drop to
      less than 1 volt in 3 seconds.

    7. If the sensor does not respond as specified, check the power and
      ground circuits.

    8. If power and ground circuits are functional, the sensor is faulty.

    EGR Valve Control Solenoid

    1. Remove the EVR solenoid.

    2. Attempt to lightly blow air into the EVR solenoid.

      1. If air blows through the solenoid, replace the solenoid with a new

      2. If air does not pass freely through the solenoid, continue with
        the test.

    3. Apply battery voltage (approximately 12 volts) and a ground to the
      EVR solenoid electrical terminals. Attempt to lightly blow air, once
      again, through the solenoid.

      1. If air does not pass through the solenoid, replace the solenoid
        with a new one.

      2. If air does not flow through the solenoid, the solenoid is OK.

    4. If the solenoid is functional but the problem still exists, check
      the power and ground circuits.

    EGR Valve

    1. Install a tachometer on the engine, following the manufacturer's

    2. Detach the engine wiring harness connector from the Idle Air
      Control (IAC) solenoid.

    3. Disconnect and plug the vacuum supply hose from the EGR valve.

    4. Start the engine, then apply the parking brake, block the rear
      wheels and position the transmission in Neutral.

    5. Observe and note the idle speed.

    If the engine will not idle with the IAC solenoid disconnected,
    provide an air bypass to the engine by slightly opening the throttle
    plate or by creating an intake vacuum leak. Do not allow the idle speed
    to exceed typical idle rpm.

    1. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34
      kPa) of vacuum to the EGR valve nipple.

      1. If the idle speed drops more than 100 rpm with the vacuum applied
        and returns to normal after the vacuum is removed, the EGR valve is OK.

      2. If the idle speed does not drop more than 100 rpm with the vacuum
        applied and return to normal after the vacuum is removed, inspect the
        EGR valve for a blockage; clean it if a blockage is found. Replace the
        EGR valve if no blockage is found, or if cleaning the valve does not
        remedy the malfunction.

    Test it.

  • Conrad Deane
    Conrad Deane Jul 14, 2010

    the concern is the misfiring of two cylinders farthest from egr. the p1401 is not a concern. i'm dealing with a #5 and #7 misfire that keeps returning after roadtests. swaped plugs, coils, injectors with known good cylinders and the same two cylinders return. simple question-- do you have pcm problems with the injector /quad drivers-whatever they are called--that would cause this cylinder,injector or coil output to drop off intermitently on accell, slight throttle???



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NO - Go to step 5.


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