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i have koeo codes i need some help with
1990 F250 351w e4od
codes are
truck runs fine most of the time but stall every now and then no pattern just randomly please help before i pull what is left of my hair out.:banghead

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DTC 67 Park/Neutral Position (PNP) switch circuit open - A/C on during Self-Test
the MLP sensor is out of Self-Test range when the gear selector is in PARK; "...Possible causes: Misadjusted linkage. Open or short in harness circuits. Damaged MLP sensor. Damaged PCM.
DTC 67; "..One poss is that the NSS (or also called the MLPS) was ok...or connector was/is bad/corroded; or AC was left on, or transmission was in gear during the Self Test..." read more
Source: by miesk5 at

DTC 67 Neutral Drive Switch (NDS) Circuit Open; "...In some cases all of us at one time or another have had to "jiggle' the column shifter to get the vehicle to start because over time things losen up from DD the Haynes Manual transmission section and there's a diagram referring to "Point A" which is the column shift linkage and the transmission tab. A sure way to correct the "jiggling" is to go underneath the BKO on the drivers side and LOSEN the "nut" on column shift linkage and tranny tab JUST ENOUGH to click the tranny tab all the way back until it stops then 2 clicks forward and tighten the "nut" the column shift linkage and transmission are in sync when you go thru the grears, assuming the steering column is in resonable condition this should help correct that problem.......TOO MANY TIMES THE NSS IS DEEMED THE CULPRIT for none start when it isn't so this is a simple check to make sure. There is also another PRNDDL adjustment, but you need to remove the black plastic collar on the steering wheel, this is usually done when an actuator breaks and using pliers drive the rod downward with key on to start.....there is usually a white cable that wraps around and attached to a small mm screw IIRC that when lossened a bit it allows you to adjust the "needle" that registers on each letter of the careful because it's attached with a very fine wire loop and easily broken. The "upper ignition actuator" is another culprit because they're made of cheap pot metal.....and a PITA job to do..."
Source: by JKossarides at FSB

DTC 67 & DTC 634; E4OD Nagging Neutral Nonsense & Pinpoint Test, Manual Lever Position (MLPS) also called Transmission Range (TR) Sensor. "...One of the most-difficult problems to diagnose on a Ford car or truck is a sudden neutral condition while the vehicle is cruising in 4th gear. Now this can have a number of causes, depending on which transmission is in the car or truck, but the cause we are going to discuss here is that #(~! *&A% Manual Lever Position Sensor – that’s right, the old MLPS. This sensor is responsible for more malfunctions than any other sensor in the system, and the kicker is that it seldom stores a code 67 or 634. Actually there is a standing joke in our industry that says, “You got a problem with a Ford, change the MLPS; it fixes everything,” which ain’t that funny because it’s not that far from the truth. Some of the problems the MLPS can cause are wrong gear starts, TCC hunting, no 4th gear, engine stalling, high or erratic line pressure and the problem that this article is about – a sudden neutral condition. Whether the MLPS is attached to an E4OD, AXODE, AODE or CD4E, the operating characteristics are the same. What that means is the MLPS is classified as a step-down resistor. The MLPS is supplied 5 volts from the computer as a reference voltage, and as the shift lever is moved from park toward manual low, the voltage in each gear-shift position will decrease as shown in Figure 1. The MLPS also can be checked for correct resistance, also shown in Figure 1. This way, if the resistance checked good on the bench but the voltage does not check good in the vehicle, you know there must be a wiring or ground problem. I know what you are thinking: You replace the MLPS on every job you do, so why should you check the resistance on a new part? Well, that’s fine, but one thing has become very clear lately: NEW DOES NOT MEAN GOOD! Now, let’s get to the meat of the problem. As you can see in Figure 1, the voltage in the drive/overdrive position can be 1.88 to 2.30 volts. The O.D. Cancel button, on those vehicles equipped with one, has no effect on the voltage seen in the drive position, nor does it matter whether the vehicle has a gas or diesel engine. This would be the voltage seen in the D or D position if it were available on the scan-tool screen in the data mode. Unfortunately, this information is not always available, and this “glitch” may occur faster than the scan-tool’s update capability so the voltage jump would be missed. Therefore, a digital multimeter must be used to monitor this voltage. This is of the utmost importance in diagnosing the sudden-neutral condition. This voltage should be monitored when the neutral condition occurs by placing the multimeter’s positive lead to computer terminal 30 if it is an EEC-IV system, as illustrated in Figure 2, or to terminal 64 if it is an EEC-V system. This wire is light blue/yellow on all applications except vehicles with the CD4E. On these the signal wire is red/black. Now, here is where this gets a little involved. The negative lead of the multimeter should be placed at the MLPS signal-return ground terminal at the MLPS. The reason is that the ground circuit for the MLPS can be shared by as many as FIVE other sensors, as seen in the wiring diagram in Figure 2. This means that there are factory splices in this ground circuit. If you check this ground at computer terminal 46 for the EEC- IV or computer terminal 91 for the EEC-V, the ground may check good but could be bad at the MLPS if there is a problem on the MLPS side of the splice, as also can be seen in the wiring diagram in Figure 2. The ground-circuit wire for 1989-90 F- and E-series trucks is black/white; all other vehicles use a gray/red ground wire except for CD4E applications, on which the ground wire is black/blue. Once the multimeter is connected to these circuits, as seen in Figure 3, place the meter where it can be seen while driving. When the transmission suddenly neutrals, be sure to have someone observe the multimeter, or use the meter’s MIN/MAX feature to record the highest and lowest voltage readings that occurred in the circuit. If the voltage jumps toward 3 volts as shown in Figure 3, and at that very moment the transmission neutrals, either the MLPS is faulty or the MLPS ground circuit is poor. Under normal conditions, this voltage reading SHOULD NOT CHANGE! When the voltage jumps toward 3 volts, this indicates a neutral-shift- lever position to the processor. This confuses the computer’s logic system, and therefore the computer is unable to fire the shift solenoids correctly (I think), and – BAM – you have a sudden-neutral condition. Why does the voltage jump because of a poor ground? The poorer the ground, the higher the resistance will be in that ground circuit. The higher resistance will cause the voltage in the overdrive or drive position to rise toward the 5-volt reference voltage, much like putting a bend in a garden hose would raise the pressure in the hose behind the bend. Ground- circuit integrity can be verified by placing the positive multimeter lead to the MLPS ground terminal at the MLPS and the negative multimeter lead to the negative battery post, as seen in Figure 4. With the multimeter set to DC volts and the engine running, the maximum voltage should be 0.1 volt. If more than 0.1 volt is seen on this ground circuit, it is NOT a good ground. In order to correct this condition, cut the ground wire close to the MLPS, attach it to a known good ground and recheck as previously described. Two things must be remembered here. One is that the return electricity will seek the path of least resistance. This path MUST be the ground circuit, NOT your multimeter. That’s why you should see a maximum of 0.1 volt on any 5-volt-reference ground circuit; 0.3 is acceptable on a 12-volt-reference voltage supply. The second thing to remember is that most electrical- fault phone calls I receive on the ATSG helpline are ground-related problems, so be sure to use the voltage-drop method of checking grounds as described. It may help to prevent you from falling into this trap..." See Diagrams & instructions
Source: by Pete L at Pointers/index.html


DTC 91 & 92 in E4OD; "...1-2 Shift solenoid circuit failure; 93 Coast clutch solenoid circuit failure(e4od), 94 Converter clutch solenoid circuit failure, 99 Electronic pressure control circuit failure, and another with two descriptions. 56 TOT reads & minus 40deg. F or circuit open and 56 Vaf or MAF circuit amove maxium voltage; I'd try pulling & cleaning the shift solenoid pack connector, and then inspect the lines from the PCM to that connector for shorts and opens. All of those codes are pointing to a problem with the connections to the solenoid pack, in the harness, or in the solenoid pack itself. I wouldn't keep driving it like you are, though. The 'default' gear is 4th, so you're creating a lot of heat trying to get going..."
Source: by SigEpBlue (Steve) at FSB


DTC 99 Transmission Control Indicator Lamp; "...That would probably be an EPC circuit failure. If this circuit fails line pressure should go to full at all times. The full line pressure puts a good deal of extra load on the engine, and will usually effect the idle. It is especially noticeable if your engine is already in need of a tuneup. You will need to check the electronic pressure control solenoid and its wiring. Either of these could be causing the EPC code..." miesk5 NOTE; So look under Bronco, for the Solenoid Body Connector - make sure it is still connected and clean inside; It's on the passenger side of the transmission. You'll need to remove a small heat shield (two bolts) next to the catalytic converter, and probably clean away a TON of gunk before yanking it. Ford wasn't too bright in designing the placement of this connector. The connector has a single press-in tab latching it in place, IIRC; It looks like this, and there's only one locking tab on it technically. But if you look at the bottom of the picture, there's one of those Ford-style mechanisms that should (repeat should) separate upon pulling the connector. You may find it helpful to pinch both sides of the connector while pulling on the harness (it won't hurt the connector). The corrosion can really be a bitch to pull against. If you still can't pull it off, you may find it beneficial to use a flat-blade screwdriver and apply some leverage to it from underneath. Make sure you've got plenty of light under there to see all. Completely seat solenoid body connector into solenoid body assembly receptacle by pushing on the top of the connector. An audible click indicates full contact. Verify connection by pulling on harness. by SigEpBlue (Steve)
Source: by Baumann Electronic Controls, LLC
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