2003 F150 PCM going bad - F150online Forums

Go Back  F150online Forums > Body > Electrical Systems
2003 F150 PCM going bad >

2003 F150 PCM going bad

Notices

2003 F150 PCM going bad

Reply

 
 
 
  #1  
Old 06-11-2018, 10:14 AM
Junior Member
Thread Starter
Join Date: Jun 2018
Posts: 5
2003 F150 PCM going bad

PCM, coil "a", and AC clutch, keep failing at the same time. Traced wires, found no problems. Truck runs, but only on 7 cylinders.
 

Last edited by Laurent; 06-11-2018 at 10:20 AM.
Reply With Quote
  #2  
Old 06-11-2018, 11:52 AM
Technical Article Contributor
Join Date: Jan 2007
Location: Vernon, NY
Posts: 7,261
What are you working on?
 
Reply With Quote
  #3  
Old 06-11-2018, 01:47 PM
Junior Member
Thread Starter
Join Date: Jun 2018
Posts: 5
Working on a 2003 F150 5.4L engine. Replaced computer, ran good for 2 days, then went bad again.
 
Reply With Quote
  #4  
Old 06-11-2018, 08:10 PM
Technical Article Contributor
Join Date: Jan 2007
Location: Vernon, NY
Posts: 7,261
Sounds like a short someplace.
 
Reply With Quote
  #5  
Old 06-12-2018, 05:57 AM
Junior Member
Thread Starter
Join Date: Jun 2018
Posts: 5
Could it be the AC clutch itself, I traced the wires from the coils to the PCM and found no problems. The truck ran good for a whole day before it went bad again. Now, as soon as I start it, it blows up coil A. (#1 cylinder). It runs good, but only on 7 cylinders.
 
Reply With Quote
  #6  
Old 06-12-2018, 06:50 AM
Senior Member
Join Date: Jan 2002
Location: Wilmington,NC
Posts: 4,150
Are you sure it's a coil failure? Have you swapped coils with another cylinder to see? What is the compression in that cylinder?
 
Reply With Quote
  #7  
Old 06-12-2018, 07:11 AM
Senior Member
Join Date: Oct 2002
Location: St. Louis (Out in the woods)
Posts: 6,387
What exactly do you mean by "blows up coil A"?

Did you verify that the clutch coil diode is present and good? It's there to absorb the transient (surge) when the clutch de-energizes.
 
Reply With Quote
  #8  
Old 06-12-2018, 07:22 AM
Junior Member
Thread Starter
Join Date: Jun 2018
Posts: 5
Coil A just blows up. Takes ten seconds after engine starts, then it blows up, literally.

Is the clutch diode right there next to coil A? I don't know. Connection looks corroded.
 
Reply With Quote
  #9  
Old 06-12-2018, 08:16 AM
Junior Member
Thread Starter
Join Date: Jun 2018
Posts: 5
If it were the clutch diode, would I need to replace the PCM again, or just the bad coil and the diode? I mean, can a bad a clutch diode also damage the PCM, or just coil A?
 
Reply With Quote
 
 
 


Thread Tools
Search this Thread
Quick Reply: 2003 F150 PCM going bad


Sponsors

Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: