Will not start unless I plug in a scan tool?

Tiny
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.
Wednesday, August 10th, 2022 AT 5:00 PM

5 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,530 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?
Images (Click to make bigger)
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Thursday, August 11th, 2022 AT 9:46 AM
Tiny
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.
Was this
answer
helpful?
Yes
No
Thursday, August 11th, 2022 AT 5:47 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,530 POSTS
Okay, yep, let me know after checking the fuse and wiring.
Was this
answer
helpful?
Yes
No
Friday, August 12th, 2022 AT 10:33 AM
Tiny
HAMED SRATH BOUKARI
  • MEMBER
  • 3 POSTS
I finally got some time and looked at the fuse and the wiring and everything looked good.
Was this
answer
helpful?
Yes
No
Monday, September 12th, 2022 AT 5:07 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,530 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.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Tuesday, September 13th, 2022 AT 9:10 AM

Please login or register to post a reply.

Related Engine Not Running Content

Car Cranking but Not Starting? Try This
VIDEO
Car Cranking but Not Starting? Try This
In­struc­tional re­pair video
Engine Not Starting
GUIDE
Engine Not Starting
Over the past 20 years at 2CarPros we have iden­ti­fied the top prob­lems that are eas­ily fixed. This guide can save you a trip to the re­pair garage or call­ing a tow truck and...
VIEW MORE