Will not start unless I plug in a scan tool?

HAMED SRATH BOUKARI

MEMBER
2014 FORD MUSTANG
3.7L
V6
2WD
AUTOMATIC
48,000 MILES

So, basically when I get into my car and try to start it with just the key it won't start, but when I plug in a scan tool the car starts and runs just fine. I have no idea what could be the problem. I'm trying to see if anyone has ever run into this problem before or know what I could do to diagnose this problem and find the root of my problems.

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

The scanner must be acting as a power or ground source, I would check the ground and the fuse# 20 in the smart junction box under the right kick panel and the grounds at the right side of the dash and the right side of the engine compartment. Here is a wiring diagram that shows you how the system works. Check out the diagrams (below). Please let us know what you find. We are interested to see what it is. Also, are there any codes?

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Thursday, August 11th, 2022 AT 9:46 AM

HAMED SRATH BOUKARI

MEMBER
3 POSTS

Okay, thank you very much. I will check that out. At one point I had a code show up for p025b, but it went away. I looked into that and ended up replacing the fuel pump control module, but that didn't do anything to it.

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Thursday, August 11th, 2022 AT 5:47 PM

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

Okay, yep, let me know after checking the fuse and wiring.

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Friday, August 12th, 2022 AT 10:33 AM

HAMED SRATH BOUKARI

MEMBER
3 POSTS

I finally got some time and looked at the fuse and the wiring and everything looked good.

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Monday, September 12th, 2022 AT 5:07 PM

KEN L

MASTER CERTIFIED MECHANIC
42,949 POSTS

It sounds like the PCM is out and is using the scanner to help the engine run, I would try replacing it with a rebuild unit you can find by searching google, have your VIN number ready, here is the location and how the job is done in the images below. Please let me know what happens.

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