How Do I test PCM signals to Coil Pack 5/2?

[eloudon123]

2011 Jeep Liberty Limited 3.7L 4WD 203,000 miles

Code: P0302 misfire on 2

I have done spark plugs, spark plug wires, replaced the coil pack that fires 5 and 2, and made sure it's not a fuel injector or fuel injector wires.

It's time to check if this is caused by PCM communication to the coil pack. Replaced the PCM with a plug and play 2 years ago because of alternator issues. It's under warranty. If I can confirm that the PCM is causing the issue, I can get it replaced for free.

Does anyone have a diagram showing the connectors and pins of a 2011 Jeep Liberty PCM? I don't even know which pins control which functions, and no amound of googling has helped me find this.

How do I test the PCM to make sure it's not causing the misfire? Please be very specific. I am new to electrical testing, so this is a big learning experience.

 

[John P.]

I know this is an older post but did the PCM end up being your issue? I'm chasing a similar issue with mine. I don't know if the PCM issue for misfires persisted into the 2011/2012 model years. In the KJ years it usually resulted in a complete failure of coil ignition due to an internal ground burning out.

 

[dtennes]

2011 Jeep Liberty Limited 3.7L 4WD 203,000 miles

Code: P0302 misfire on 2

I have done spark plugs, spark plug wires, replaced the coil pack that fires 5 and 2, and made sure it's not a fuel injector or fuel injector wires.

It's time to check if this is caused by PCM communication to the coil pack. Replaced the PCM with a plug and play 2 years ago because of alternator issues. It's under warranty. If I can confirm that the PCM is causing the issue, I can get it replaced for free.

Does anyone have a diagram showing the connectors and pins of a 2011 Jeep Liberty PCM? I don't even know which pins control which functions, and no amound of googling has helped me find this.

How do I test the PCM to make sure it's not causing the misfire? Please be very specific. I am new to electrical testing, so this is a big learning experience.

Did you ever get this resolved? I have the same apparent problem (p0304) on cyl 4.

 

[dtennes]

I've got what sounds like the same problem as yours. Please look here if you have a minute and share your thoughts, thanks!

2003 Liberty 3.7L sport, Reman engine from Tri-Star, p0304 code

I'll share what's going on, and if anyone has anything to contribute I will be most grateful. Back ground: 1. 2003 Jeep Liberty Sport 4WD 3.7L 2. Blew a ring and trashed the engine 3. Had a Goodyear shop (excellent credentials, and past personal experience with them so I trust them) install a...

www.jeepkj.com

 

[dtennes]

Did you ever solve the problem?

 

[LONGJEEPOWNER]

I have had the same issue with my 2010 Liberty. When it throws the code there has been probably 2 to 3 months in-between. I changed the plugs, coils and wires to no avail. I was thinking it might be a fuel issue. We have been getting some bad gas here! (water).