After it was turned off it did not start again?

Tiny
2001 EXPLORER
  • MEMBER
  • 2001 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 138,000 MILES
My vehicle started to act up on the way home (loss of spark or fuel). I made it home, but then the truck would not start. I towed it to the mechanic, and it started and ran for a while. After it was turned off it did not start again. So, the problem seems to be intermittent. We spent a little time together diagnosing and there were no trouble codes or check engine light. The fuse/relay box in the engine compartment did not have ground turned on from the PCM. Is this a known issue with older Explorer? Could this be caused by the PATS? (Drained battery in the key fob?) I had read that PATS would not disable a running vehicle, only prevent it from starting.
Friday, June 30th, 2023 AT 11:50 AM

13 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

You are correct. PATS (passive anti-theft system) will prevent it from starting and not shut it down.

As far as a ground turned on, I need more info on that one. I'm not familiar with such a thing.

Has the crankshaft position sensor been checked? If can fail and not set codes.

Try this. See if it starts using starting fluid. If it does and then stalls, we know it's a fuel-related issue. If there is no change, chances are there is no ignition spark. In this case, I will need you to check for spark.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-for-ignition-spark

One other thing. Have you tried resetting the inertia switch? The Inertia Fuel Shutoff (IFS) switch on the RH toe board. You can reset it. (See pic 1 below)

Let me know.

Joe

See pic below.
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Friday, June 30th, 2023 AT 10:57 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Thanks Joe, it has spark. I can hotwire the fuel pump and it will run so the fuel pump works but the relay in the under-hood fuse box is not getting ground. Several relays are not getting ground. Weirdly, the ground is turned on and fed by the PCM. My understanding is that this is how PATS works, it shuts off the ground. Yes, I have checked the inertia switch. The intermittent part is what gets me and no trouble codes and the fact it started acting up when driving. I will check the crankshaft position sensor. Is that common to be intermittent when it goes out?
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Saturday, July 1st, 2023 AT 8:59 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Interestingly, a failing crankshaft position sensor can work, get warm and stop working, and not allow the vehicle to restart for a period of time or not at all. However, if the sensor was bad, you wouldn't have spark.

Take a look at this link:
https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

Just for curiosity, will it start and then stall if you use starting fluid? Also, is the security light staying on that could indicate the PATS is activated?

If the fuel pump relay isn't getting ground, you are correct. A ground path is provided via the PCM to complete the primary side of the relay. See pics below.

So, if you are not seeing ground from the PCM, the next thing to do is check at the PCM connector.

Keep in mind, the PCM has a ground as well. It is on the left side of the radiator support.

Let me know.

Joe

See pics below.
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Saturday, July 1st, 2023 AT 7:11 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Thanks Joe. I haven't tried starter fluid but I can jumper the fuel pump to hotwire it and the truck will start. So, I’m getting spark. I've checked and rechecked the PCM ground. I feel like it's down to the PCM going bad or something in the wiring harness or the fuse/relay box itself. Is there a way to “open up” the fuse box under hood? It looks pretty sealed and one-piece plastic. I would like to get into it and trace the grounds and look for anything wrong before swapping the PCM and having it reprogrammed to pats.
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Sunday, July 2nd, 2023 AT 7:35 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Okay, that leads us back to the power supply at the pump. We need to check at the PCM for a ground path for the relay. Also, have you confirmed there is power to the primary side of the relay? If there is power to the primary side and we have a ground path, that should actuate the relay.

Sorry for so many questions. Not being there makes wiring issues a little more difficult. Also, have you checked for power to and from the inertia switch? Maybe it's failing.

Let me know.

Joe
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Sunday, July 2nd, 2023 AT 1:41 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Yes, electrical is not my favorite to chase down especially when it is intermittent. And yes, I have positive power to the relays. I should say that this is a project vehicle, and I stopped my diagnosis when I discovered the PCM controlled the relays by turning on the ground. That was new to me, and it looked like I would need to start unwrapping the wiring harness to trace the ground distribution wires and connections. I don't have time this weekend to dive back into it, but I am trying to get sage advice from more experienced people to help me formulate a logical game plan when I do have time to go back to it. I was hoping this was common and there was a known culprit and remedy. But it sounds like I need to just continue with the logical progression through the harness. Do you know if there is a way to open up the relay box more and get to the bottom of it where all the wires come in?
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Sunday, July 2nd, 2023 AT 2:28 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

I totally understand. When you get back to it, check for a ground path right at the PCM. You won't need to take the wiring apart. As far as the relay box is concerned, I believe it is bolted in place.

Let me know.

Joe
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Sunday, July 2nd, 2023 AT 2:36 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Thanks Joe, from your earlier diagrams it looks like I need to look at pin 103 with a black/white wire? Number 570 in the diagram? Is that your understanding of the ground to the relays that is controlled by the PCM?
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Sunday, July 2nd, 2023 AT 2:45 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

That is the PCM's ground. Using that ground, the PCM provides a ground for the relay via pin 80 (light blue wire with an orange tracer).

Let me know if that helps.

Take care,

Joe
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Sunday, July 2nd, 2023 AT 10:53 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Joe, where do you get your wiring diagrams? Haynes and Chilton manuals don't have the detail they used to. I have tried a couple subscription services but wasn't satisfied. What do you recommend?
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Monday, July 3rd, 2023 AT 5:23 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

I have access to both Prodemand and Alldata. Both are good. Have you ever used one of them?

Also, please feel free to let me know if I can get something for you. It's no problem.

Take care and Happy 4th.

Joe
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Monday, July 3rd, 2023 AT 9:26 PM
Tiny
2001 EXPLORER
  • MEMBER
  • 7 POSTS
Thanks Joe,

It has been over 20 years since I ran an automotive shop and we had AllData for the shop. I didn't use it much as a manager and I remember it being too expensive for personal use but I see now they have DIY for the home user, but it is single vehicle specific. Still not a bad cost if you have a long project and want a one or even three-year subscription. I haven't used Mitchell in a very long time, used to go to the library in high school to look at the manuals there and get answers and copy diagrams. I will look at Prodemand. I did find a 2000 4.0 OHV PCM PIN Out online. I assume 2001 would be the same. And how different is the SOHC engine as far as PCM and wiring harness? Besides worrying about PATS, the PCM's wouldn't be interchangeable from OHV to SOHC would they? How about the wiring harness? Is the harness specific to the engine? Different sensors? I ask because I have a SOHC parts car available to me if anything were compatible with my OHV.
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Wednesday, July 5th, 2023 AT 9:54 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

As far as Alldata is concerned, you should have access to any vehicle they have online. It's my go-to.

As far as the wiring harness and PCM are concerned, they will be similar, but there will be differences. Since you have a parts car available, compare the two. You may find them the same for your needs.

Let me know.

Joe
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Thursday, July 6th, 2023 AT 8:43 PM

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