Engine won’t turn off, 4wd issues

[Frenchy]

Guys this fucking thing is giving me so much anxiety. Do I just start digging in there myself so that they don’t deny my warranty claim if a bunch of rats chewed through it? I’m out several thousand on rental cars right now anyway. If I leave it as is and say it’s fixed they’ll give me the rental car fees and I’ll start lemon law proceedings. It’s my 31st birthday today too and I decided to drive the 5.0 with the top down to try to get in a better mood. It helped a bit, but it also really got me thinking about how to proceed.

Just turned 31?! You are young!! I just turned 32 yesterday!!

If you feel it would be best to go through the lemon law then make sure you have all your 's in a row. If anything is out of place things can go wrong

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[airline tech]

Manual Description:

Computer Controlled Shutdown
The PCM controls the PCM power relay when the ignition is turned to the ON or START position, by grounding the PCMRC circuit. After the ignition is turned to the OFF, ACC or LOCK position, the PCM stays powered up until the correct engine shutdown occurs.

The ISP-R and the INJPWRM circuits provide the ignition state input to the PCM. Based on the ISP-R and INJPWRM signals the PCM determines when to power down the PCM power relay.


So, until I can dig farther:
This is what I think should happen if you pull fuse 28 in the BJB
It should shut down the engine. if it is running
Not confirmed as of yet. (This is accurate)

Unless it still sees power from another source - shorted power source

Plus, with a scan tool - live data pid's should show this switch position (ISP-R) - On/Off
If I am correct, this data pid will always show (on)

The PCM is located under the BJB, you can try wiggling the wire harness to it - to see if, when you have put switch to off.
See if engine will shut down.

 

[airline tech]

I know I have thrown out a lot of information here and I could be wrong in my diagnosis, but I am taking your symptoms and looking at the wiring pinouts.
I even found that the wires are pinned next to each other at the BJB as well.
It's too much of a coincidental power feed to overlook as a possibility.

The BJB Connector C1035B - is on the left (as you are facing it) (Inboard side of engine bay)
This is the Pinout:
Pin 43 Goes to PCM Connector C175B Pin 82 - Brown Wire w Green Stripe
Pin 41 Goes to PCM Connector C175B Pin 64 - Grey Wire w Violet Stripe

The PCM is buried under the BJB and the BJB has to be removed to get to it.
The PCM has 2 main connectors going to it
C175B - will be the most forward connector (To the front of the truck)

I cannot visually see how the C1035B harness routes down, as its buried.
The harness is wrapped in protective loom and tape.
You may get lucky and find damaged wires at the BJB Connector (there is a protective cover on the connector)

The harness run, from the BJB connector follow it down to a possible branch out of wires going to the PCM connector.
If no visible damage to the harness, then you are going to have to rip apart the protective loom.

You could also have the short inside the BJB box itself or the PCM Itself
But I have a strong feeling its just wiring

PLEASE at least try this below

A possible confirmation of my diagnosis.

With Engine in a Non- Shut Off) condition
Pull 4WD Relay -CW - - See if engine dies or you are able to shut off the truck at the Ign Switch
Pull 4WD Relay CCW - Same
If you get engine to shut off, then this verifies my diagnosis.
Or
Pull the relays one at a time and start / shut off engine - TEST
Does it now work correctly (Shut-Down)?

What this will do is kill that half of the power feed and create an open circuit.

 

[sandy_koufax]

I’ve decided there’s a short somewhere in the battery junction box. Pulling fuses 32 (fuel pump), 86 (4wd) and 42 (4wd) make the not cutting engine issue go away. Pulling 86 and 42 make all the problems go away except “4x4 fault”. Dealer rush ordered the part for me. I’m taking the truck in with a box of donuts. Will update everybody soon.

If it’s not actually this issue, well I don’t care, I’ve decided this is the issue and that’s that. I’m not picking up the truck until it runs like a 3 year old 33k mile union made truck should.

 

[bsr956]

again airline tech goes beyond the norm and brings solutions!

Airline Tech's skills scares me!!

 

[airline tech]

I’ve decided there’s a short somewhere in the battery junction box. Pulling fuses 32 (fuel pump), 86 (4wd) and 42 (4wd) make the not cutting engine issue go away. Pulling 86 and 42 make all the problems go away except “4x4 fault”. Dealer rush ordered the part for me. I’m taking the truck in with a box of donuts. Will update everybody soon.

If it’s not actually this issue, well I don’t care, I’ve decided this is the issue and that’s that. I’m not picking up the truck until it runs like a 3 year old 33k mile union made truck should.

Thats probably not a bad idea, as long as the wiring between the PCM and BJB is tested and confirmed good. (with a shake test) and meter leads across both circuits.

Example: Between Pins 41 & 43 at the BJB connector plug - Ohm Reading should remain (OL) Open
if you get continuity at any time with the shake test, validates shorted wires.

With the relays and all fuses still installed in the BJB, you can do the same test at the BJB (Internal)
Connector to validate the short is internal of the BJB itself.

 

[sandy_koufax]

Thats probably not a bad idea, as long as the wiring between the PCM and BJB is tested and confirmed good. (with a shake test) and meter leads across both circuits.

Example: Between Pins 41 & 43 at the BJB connector plug - Ohm Reading should remain (OL) Open
if you get continuity at any time with the shake test, validates shorted wires.

With the relays and all fuses still installed in the BJB, you can do the same test at the BJB (Internal)
Connector to validate the short is internal of the BJB itself.

I hate that you’re right. Drove the truck today without the relays and had the same issues come up. I think my “fix” from last night was just jostling the BJB into compliance when I removed the relays. Do you have any advice on which harnesses and wiring to look at first (like in what order) so that I avoid taking apart as much as possible? Also where they physically are located. I see the two harnesses that have the lever connecting to the top of the BJB. I usually shut off the engine by disconnecting the one on the right.

 

[Big Blue]

I have to say, this thread has probably scared me the most of any issue I've seen on here. Not being able to shut the engine off. With all the drive by wire tech in our vehicles, does this also mean it could randomly start itself, if I'm working under the hood? Do I need to be sure I put the fob in a Faraday bag when I do?

I also have to say, I'm incredibly impressed with @airline tech , the amount of his time he has spent researching other people's issues to help them. Along with his thoroughness and clear explanations is outstanding. He is a troubleshooting God, and should probably be getting a paycheck from Ford.

 

[sandy_koufax]

I have to say, this thread has probably scared me the most of any issue I've seen on here. Not being able to shut the engine off. With all the drive by wire tech in our vehicles, does this also mean it could randomly start itself, if I'm working under the hood? Do I need to be sure I put the fob in a Faraday bag when I do?

I also have to say, I'm incredibly impressed with @airline tech , the amount of his time he has spent researching other people's issues to help them. Along with his thoroughness and clear explanations is outstanding. He is a troubleshooting God, and should probably be getting a paycheck from Ford.

Definitely agree with all you said.

Also, Airline Tech, please DM me your favorite national chain restaurant or liquor store so I can buy you a round.

 

[airline tech]

I hate that you’re right. Drove the truck today without the relays and had the same issues come up. I think my “fix” from last night was just jostling the BJB into compliance when I removed the relays. Do you have any advice on which harnesses and wiring to look at first (like in what order) so that I avoid taking apart as much as possible? Also where they physically are located. I see the two harnesses that have the lever connecting to the top of the BJB. I usually shut off the engine by disconnecting the one on the right.

The issue connector is the BJB (Left) side as you are facing it. C1035B

You may try, disconnecting and inspecting this connector (pins) look for moisture / water or any Dis-Colorization on them.
Moisture in this connector could possibility create the same issues you are having with moisture being the conductor.
If you have some electrical contact cleaner, spray the connector down, let it dry and reconnect.
It is possible the cross short is at this point.

When the truck shifted into 4WD Lo - The original starting point for all this:
Was it Raining? or had you recently driven through a heavy rainstorm? or Car Wash - Engine Bay?

If YES, then I would lean more on the BJB or Connectors to it, as getting wet and creating the issues you are having.


From this connection, the harness routes down towards the PCM

This is where it gets difficult (for access) The PCM is mounted under the BJB, so the only way to access it - is to remove the BJB or possibly remove the battery to access the PCM connector (C175B)

The BJB connector harness should have a (branch out) of wires going to the PCM connector (C175B)

PCM Connector - C175B - should be the forward connector in the mounted position,

So, this is one of those things that may not be easy (from a manual) perspective.
Manual (all you have to do is)
but in real life (it is difficult to do)

And I am pointing to the need to get access to the PCM connector and have the BJB connected and have the battery installed for the test procedure and still be able to get to the PCM connector.

To prevent damage to the connector sockets / pins it is best to have the proper test leads to avoid spreading the sockets apart.
An alternate solution for this is a paper clip or sewing T-Pin, as long as you are very careful and use this to make your test lead contact and use an alligator clip to hold the probe to the paper clip or T-Pin.
The alternate solution however does not always give you the best connection (solid and valid)

Being that you have pulled the 4WD - Relays and got it working validates that this circuit is cross shorting over to the ISP-R circuit. (Even temporarily)

The short is located anywhere between the Internal BJB Box to the PCM Internal Circuit Board.
The harness run is approximately 18 inches (between the BJB and PCM)
I do not believe that the issue is with the PCM, I believe its upstream of it.

So, to isolate the circuit and separate the (BJB) internal vs Wiring short.

These needs checked:
Note: disconnecting and moving the harness may temporally fix the issue and give you invalid results. hence the importance of the shake test

Disconnect C175B (PCM Connector)
Pull the 4WD (CW) Relay
Probe Pin #80 in the C175B connector (Positive Test -Lead), get a solid and valid connection.
Turn Ignition (ON) -- (Engine - OFF)
Take Negative (Meter) Lead and Touch to a good ground point.
NOTE: Pin #80 - should be a Grey Wire w Orange Stripe

(You should not be reading any voltage)
If you get a voltage reading, the ISP-R circuit is feeding it, showing the cross short.

Are you reading any voltage.
Yes - Confirmed short to voltage.
shake the harness and see if you can get voltage to drop, if yes, then slowly move along the harness slightly shaking, bending and twisting it to locate the problem area in the harness.
No - Shake test the harness to see if you can make voltage appear, doing the same as above.
No- Tap on the BJB Box, see if you can make voltage appear.

If you have voltage reading and harness shake test has no effect, then move up to the BJB connector.
Disconnect it and match pin BJB Connector Pin #22 to the BJB Box (Integral Connector)
NOTE: Pin #22 - should be a Grey Wire w Orange Stripe

Repeat Test as above using the (BJB) Box Integral Connector that matches Pin #22
Positive Lead (here) and Negative Lead to Ground
Do you still get a voltage reading?
(Yes = short is integral to the BJB)
(No = short is in the wire harness)

Repeat same test for the 4WD CCW Relay, reinstall the CW relay and remove the CCW relay
and then test again using different pins on the connectors.

PCM Connector (C175B) Pin #82 - Brown Wire w Green Stripe
BJB Connector (C1035B) Pin #43 - Brown Wire w Green Stripe

NOTE: A secondary CONFORMATION of voltage cross shorting between the 4WD Relay and the
ISP-R circuit

Install both 4WD Relays.
Pull BJB - Fuse 28 (Possibly Labeled PCM) 10 Amp Fuse
Disconnect PCM Connector (C175B)
Ignition (ON) - Engine (OFF)
Probe Pin #64 at the PCM Connector (Red Lead) and (Negative Lead to Ground)

Voltage Present?
Yes - (Confirmed cross short) from the 4WD Relay Circuit
You should not have voltage with the Fuse Removed (Fuse 28-BJB)
This alone validates you are on the right track.
Be sure to shake test the harness for this as well.

This test will show which of the 2 relay circuits are shorting over to the ISP-R circuit.
This test will also hopefully isolate the wire harness vs BJB (Internal Short)
This is where the harness shake test is important as well as a solid / valid connection to the pins you are checking, the connection needs to be secure enough that you can shake the harness and still have a good solid connection.

I suspect the cross short (if in the harness) is going to be at the (connector) itself, the transition from the back side of the connector to the harness, exposed wires or at a bend point in the harness or area where the harness can possibly rub on a bracket or engine bracket.
I would closely inspect any exposed wires in the harness before ripping apart the harness loom.

Note:
In the 2019 / 2020 wiring diagrams the Pin #'s for the PCM are the ones I have listed.
In the 2021-2023 wiring diagrams the Pin #'s show different at the PCM (C175B)
The wiring colors did not change and the BJB Pins did not change.
So, if you run into - Pin # 80 and 82 being empty cavities (C175B)
Then the Pin #'s are as follows:
Pin #80 is now moved to Pin #60
Pin #82 is now moved to Pin #63

 

[VegasP11]

I just noticed that @airline tech is in KS. I know who I am hitting up if I have a problem with my Ranger!

 

[airline tech]

Example of where I suspect problem lies:

Exposed Wires under the cover

The unknown is does the BJB have a wired run like the Aux Relay Box or is it a printed circuit board?

Thus far it appears the BJB is a SEALED box, as reported by another member.


If it is like the Aux Box below
Then you may be able to get the BJB apart and check for damaged wiring
If so (BE VERY CAREFULL - Pulling it Apart)
These 2 locations would be a fairly quick check, without a meter or wiring checks.

 

[sandy_koufax]

Thanks for everybody’s help. I was putting off checking the pins/wiring until this weekend but it looks like ol’ Henry Ford had other plans for me. I unlocked this cool little light on my dash today. I really like how it matches the colors of my vintage california license plate. Really ties the whole car together.

Airline Tech, I appreciate everything you’ve done so far. I’ll relay this info to the dealer. I’m going to drop it off in a few hours.

 

[airline tech]

Thanks for everybody’s help. I was putting off checking the pins/wiring until this weekend but it looks like ol’ Henry Ford had other plans for me. I unlocked this cool little light on my dash today. I really like how it matches the colors of my vintage california license plate. Really ties the whole car together.

Airline Tech, I appreciate everything you’ve done so far. I’ll relay this info to the dealer. I’m going to drop it off in a few hours.

Just curious, if the dealer found and fixed the issue

 

[sandy_koufax]

Just curious, if the dealer found and fixed the issue

I told them I think it’s the BJB or harness. They believe it’s the PCM. Its getting installed monday so we’ll know more then.

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