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Ask Dodgerench Your Own Question
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3406
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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I have a 2001 dodge Dakota 5.9 with pcm issues I have two

Customer Question

I have a 2001 dodge Dakota 5.9 with pcm issues I have two pcms one gives code p0601 the other gives code p1686 it runs with the one that gives the 0601 code until it gets to operating temp then cuts off when I start slowing down to stop but it cranks back up. thanks for the help...
Submitted: 1 year ago.
Category: Dodge
Expert:  Dodgerench replied 1 year ago.

Hi, welcome to JustAnswer!. This is Ed.

A P0601 code is unfortunately the death knoll of a PCM. It's recognized an internal failure of the unit and produced this code. There's no other known reason for the code other than a bad PCM, so anything that happens beyond this point -- stalling, etc -- has to be taken in context. You will unfortunately be needing a third PCM.


Customer: replied 1 year ago.
what about the one with the code p1686
Customer: replied 1 year ago.
Customer: replied 1 year ago.
Expert:  Dodgerench replied 1 year ago.

Hi, Ed.

That's a communication issue with the instrument cluster. If the engine continues to run with this PCM, it's one way of telling us that the running problem is with the other unit, not with the truck. On the other hand, if the P0601 PCM never sets a P1686 code, it also suggests the P1686 isn't internal to THAT controller and may be related to the other one. It does get complicated.

Do you have cluster drop-out of the P1684 controller at times when the engine still runs?

And does the cluster ever drop out other than when the engine quits with the P0601 unit?

Customer: replied 1 year ago.
it cranks then shuts off with the 1686 one..
Customer: replied 1 year ago.
I don't understand about the cluster drop out
Expert:  Dodgerench replied 1 year ago.

That doesn't bode well for that controller. If you can't get it to run for more than a few seconds, yet the other one runs much farther, it shows there is a basic problem with that P1686 unit. If simply changing to the P0601 controller buys you even a minute more run time, I'm sure it's a very basic internal problem with the P1686 PCM or there wouldn't be any difference. This is one of those times when it's absolutely golden to have a different controller on hand.

Expert:  Dodgerench replied 1 year ago.

The code just describes a communication problem between the PCM and the instrument cluster. It can be caused by a number of things, but may not even have a physical manifest.

Expert:  Dodgerench replied 1 year ago.

That one controller sets this code and the other doesn't shows that the problem is internal to that controller once again.

Expert:  Dodgerench replied 1 year ago.

Plus, unless it's an exact replacement part number, you may have a mismatch of communication buses. We changed from CCD to PCI around this model year, so your PCM might not be on the same wavelength as the truck. Hard telling.

Customer: replied 1 year ago.
you got me.. so I need to send the pcm off to get repaired again then..
Expert:  Dodgerench replied 1 year ago.

Vehicle theft alarm is dependent upon communication between the theft module (CTM) and the PCM for it to allow engine start. Lacking that, it shuts down the injectors right away.

The P0601 controller (that sort of runs) is your best bet. No doubts exist in my mind that it's got problems with that code.

Customer: replied 1 year ago.
or just get another one from some were else..
Expert:  Dodgerench replied 1 year ago.

Yup. That code just plain can't be fixed.

Customer: replied 1 year ago.
what about replaceing the theft module
Expert:  Dodgerench replied 1 year ago.

You could do that, but it has to be done along with the PCM. Each one knows that the vehicle HAS theft and will tell the other if replaced individually. So if you do have factory theft, replacing the CTM without doing the PCM at the same time will result in the PCM snitching the CTM out and both will expect factory theft to be present. To completely remove factory theft, you have to replace both modules with ones that have no theft programmed -- NEW ones, in short-- and at the same time. That gets expensive and fast.

Customer: replied 1 year ago.
Expert:  Dodgerench replied 1 year ago.

You're welcome. Please remember to rate our talk and be assured I'll be available for followup with no additional charge later.