Hey everyone who sees this thread................. I'm having a few problems with my 1991 F-150 XLT Lariat. I was having some issues a few weeks ago with the fuel pump continuously running when the key is in the on position (Engine Off) and it was idling like it was full of rocks or something.............. there was also a secondary issue with the truck taking off as if it was in 3rd gear, but I could manually shift it to 2nd via column yet it seemed as if it couldn't find 1st (someone on another forum had described this as "Limp Mode" but others argued this)................ after about a week of asking around, searching Google, watching YouTube videos, and doing my own half *** diagnostics.......... I determined that it was a bad PCM, and afterwards I verified this by removing the PCM and examining the board to find 2 leaking capacitors that had corroded the pins.................

So......... I replaced the PCM this past Friday and that cleared up the issues with the idle and the fuel pump running continuously, but the truck still acts like it is getting #rd gear when I put it in D.............. I've taken the column apart just to make sure there was nothing out of place that would be preventing the shift arm from moving freely since I had replaced the Ignition Actuator about a month ago but found nothing...................

My next moves were to perform a KOEO and a KOER test to narrow my causes down, and it should be known that this was my very first attempt ever at performing wither of these self tests....................

So I tried the KOEO test first, using a paper clip as a jumper and reading the CEL.............. I got back a code 67 and a code 52. I believe the 52 code refers to the Power Steering Pump not being cycled or something but I didnt think that had to be done in an Engine Off test................. as for the 67, it refers to either the MLPS, Park/Neutral switch, or a few others.............

52 - Power Steering Pressure Switch/circuit open – PSP (This Relates to Power steering switch or circuit - not activated during test OR Idle tracking switch)
67 - Park/Neutral circuit fault – PNP/Transmission Manual Lever Position (MLP) sensor circuit – Transmissions (This Relates to Air Conditioning ON or Automatic Transmission in D or circuits)

As for the KOER test, I can't even get the truck to respond to this attempted test............. I warmed the truck by running it at 2k RPMs for 2 minutes to warm the sensors and shut it off, connected jumper then restarted........... waited for the Engine ID code to flash (4 flashes) but I got no response from it and I tried it 4 times so far................ and I believe my KOEO test codes are actually my fault, but I'm positive the AC is not on as it is in the "off" position and the temp arm all the way to the red

I'm not great with trucks, I learned the old way of diagnosing things from my grandfather and uncle where they could simply listen to a vehicle and tell you what was wrong with it.............. I do not possess that gift so I'm asking for a little help

I need to know the exact steps, I mean EXACT, that I need to perform on my truck to get a good set of codes back from it because it's getting annoying not being able to figure this out............. And I need to know why I'm getting nothing from attempted KOER tests, as I believe these would be the more helpful of the two tests.............. any point in the right direction would be greatly appreciated. I'm an IT guy and this EEC testing stuff is rather complicated if you're new to it

My trucks specs:
1991 Ford F-150 XLT
302 5.0l V-8
Mileage: 138,252
Body Code: DB4
Standard Cab, Long Wheelbase
Trans Code : E (E4OD) 4 Speed Auto w/ Overdrive
Axle Code: 19 (3.55 Non-Limited Slip)
Front GAWR: 2800lb
Rear GAWR: 3166lb
Fr/Re Tire: P235/75R15XL
Power Windows/Locks
Dual Fuel Tanks

 

Welcome to FTE neighbor. Arguments happen here too, but for the most part it's not bad.

Congrats on doing some tech work on an old horse and making progress.

Don't sweat the PS pump code & the 67 might be an issue that could be taken care of with an adjustment of the MLPS switch (image shown in this thread):

https://www.ford-trucks.com/forums/1...g-problem.html

or the updated Motorcraft replacement switch. (Plugs in from side, original style plugs in from the top)

Sometimes there can be issues with the pins of the plugs that go into the transmission where they back out or the wires are frayed. You might inspect them too.

Her's the best manually code checking tutorial I know, short of buying a OBDI reader:

http://www.fuelinjectedford.com/page13.html

Before I had a reader, I had a long wire with a switch so I could sit in the seat & ground the plug.

Welcome again & good luck.