P0601 code 2003 Jeep WJ

[dlundblad]

This is on my 2003 Jeep WJ. P0601 internal control module memory checksum error. Supposedly this means a failing ecm. My Jeep had the CEL last week. Ran fine, but battery voltage read low when I checked that evening. (12.6 or so.) Topped it off overnight with a maintainer and she was good the next AM.

CEL came back today. Once again, ran fine. Got home and let it idle outside while I took care of the dogs as I had to leave right away and came out to it surging. Tried moving it out of the way and it died. Restarted no problem, but wouldn’t idle. I held the peddle at 2000 rpm or so and it was fine. Ran okay immediately after. Parked it and there she sits.

I’m guessing alternator seeing how it ran fine while cruising down the road. What say you all? Thanks in advance.

 

[jeepman3071]

Have you checked the voltage with the jeep running to verify the alternator is charging?

 

[dlundblad]

Have you checked the voltage with the jeep running to verify the alternator is charging?

It’s been idling just fine for about 10 mins and I’m getting ~13.75v.

*just now turned it off. Had it idling 30 mins and still at ~13.75v.

 

[K2K2]

My '04 had weird stuff happening, turned out there was corrosion in the cables extending about 8" under the insulation. Once I replaced the bad cables, all was well.

So check the cables, AND the battery with a load test.

 

[grasscutter]

Is that the Chrysler Pentastar V6? That thing is famous for wearing out camshafts and cam followers. Causes all kinds of codes.

 

[clinebarger]

Those are known for failing ECM's, But modules in general need good voltage & don't like A/C Ripple from a bad diode/s in the Alternator.

 

[dlundblad]

Those are known for failing ECM's, But modules in general need good voltage & don't like A/C Ripple from a bad diode/s in the Alternator.

Is this something that can fail intermittently? Going to be hard to get it tested/ warrantied if so.

 

[BC1]

My '04 had weird stuff happening, turned out there was corrosion in the cables extending about 8" under the insulation. Once I replaced the bad cables, all was well.

So check the cables, AND the battery with a load test.

Same story with me on a 00 WJ. I changed both battery cables but I think the real cause was the ground end on the block.

 

[Chris142]

Is that the Chrysler Pentastar V6? That thing is famous for wearing out camshafts and cam followers. Causes all kinds of codes.

Wrong engine

 

[K2K2]

Is that the Chrysler Pentastar V6? That thing is famous for wearing out camshafts and cam followers. Causes all kinds of codes.

Like Chris said; this is either the 4.7 V8 but more likely the venerable 4.0 inline six.

OP has not said... @dlundblad

 

[clinebarger]

Is this something that can fail intermittently? Going to be hard to get it tested/ warrantied if so.

The PCM is known for random stalling from solder joints & they just starting acting up & throw internal death DTC's.

On the other hand, It needs to be diagnosed first. Above 12vdc & no elevated grounds at the PCM.

 

[jeepman3071]

It’s been idling just fine for about 10 mins and I’m getting ~13.75v.

*just now turned it off. Had it idling 30 mins and still at ~13.75v.

That sounds like the alternator is working okay. I would definitely clean all battery cables and connections and make sure they are tight. I remember my dad's 99 WJ being sensitive to the battery cables being clean/tight.

 

[dlundblad]

That sounds like the alternator is working okay. I would definitely clean all battery cables and connections and make sure they are tight. I remember my dad's 99 WJ being sensitive to the battery cables being clean/tight.

I will double check them.

Made the mistake on Friday of taking her to Menards. OD off, AC on. Pulling a 6x12 trailer with a big beaver tail. Lost OD and cruise while going 65. Died at the next light. I was able to get it home, but it definitely seems like an ECM.

I think the ultimate fix is a used 5th gen 4Runner. *I kid. I’ll check grounds, but will likely get ahold of Wranglerfix for a rebuilt ECM. It’s tied to the vin so my 04 parts WJ won’t work.

 

[jeepman3071]

I will double check them.

Made the mistake on Friday of taking her to Menards. OD off, AC on. Pulling a 6x12 trailer with a big beaver tail. Lost OD and cruise while going 65. Died at the next light. I was able to get it home, but it definitely seems like an ECM.

I think the ultimate fix is a used 5th gen 4Runner. *I kid. I’ll check grounds, but will likely get ahold of Wranglerfix for a rebuilt ECM. It’s tied to the vin so my 04 parts WJ won’t work.

WranglerFix has a great rep on the TJ forums so I wouldn't hesitate to contact them.

 

[BC1]

Pulling a 6x12 trailer with a big beaver tail. Lost OD and cruise while going 65.

Did you get the transmission hot light and OD light flashing? I had a WJ when living in Abu Dhabi and that was a regular occurrence. Happened when trying to keep up with traffic (140kmph) in the hotter months. Cycling the ignition and slowing down would correct it.

Point being, pulling that trailer in the heat might be a separate issue unrelated to the P0601.