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Robert R
Robert R, ASE Certified Master
Category: Dodge
Satisfied Customers: 4537
Experience:  Dodge Master Certified, Dodge Sprinter Certified
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The ecm on side of engine was replaced last night. had

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the ecm on side of engine was replaced last night. had original tested and tests fine. no voltage when running. when I hook up external voltage regulator everything works fine. again is there a fuseable link on the 2 wires from alternator to pcm or ecm on side of engine? I drove the truck with the external voltage regulator system for 2 months while waiting on the new pcm/ecm/ecu that was flashed for the vin and installed last night with same issue using the new pcm/ecm/ecu installed on drivers side of engine.

Hello, welcome and thanks for asking your question. My name is*****'m a Certified Auto Technician with 29+ years experience. I will do my best to assist you. please keep in mind that I may need to ask questions of you before I can answer. When you reply please feel free to add as much detailed information as possible pertaining to your concern.

I am researching this concern for you and will get back with you as soon as possible, Thanks for your patience while I gather the information needed for your answer. Your understanding is greatly appreciated.



Customer: replied 8 months ago.
wondering if there is a fuseable link on 2 wires from alternator to pcm/ecm/ecu on side of engine. if so I would guess it probably failed. truck has new alternator, had tested. works fine. new batteries and cables as well. that's why I/m wondering about fuseable link case when external voltage regulator is hooked up everything works fine.

No, there is no fusible link between the alternator and the ECM. It is likely, though that one of those wires is shorted or open somewhere. If you have a multimeter you will need to ohm out the two wires between the Alternator and the ECM C1 connector. You need to check the resistance of each wire and you need to check them for a short to ground and for a short to power..

For now, I'm posting the wiring diagram of the charging circuit so you can see that there are no fuse links and the wires run directly from the alternator to the ECM.

--->> Click Here to view <<---

If you need the connector pin charts for the ECM let me know...

Thank you,


Customer: replied 8 months ago.
that's what I figured. I was going to open up the wire loom and chase the 2 wires down for visual inspection then test them out and repair or replace if necessary.

It's probably easier to just ohm out the wires between the two connectors and if you find a bad one just run a new wire from connector to connector. The engine harness on a 6.7 can be a difficult challenge to open it up, then it can affect the integrity of the harness and cause other problems to crop up in a short time if you do open it up and don't get it wrapped back up properly. . Anytime possible I always try to not open up the wiring loom if at all possible.

Customer: replied 8 months ago.
Couldn't get a wire diagram thanks for that. I know its only about 3 ft of wire to chase out, but needs to be done. I have new wire loom to replace the old when I take it off. have had to do this in the past. will test wires firs though. I would rather troubleshoot and find the problem rather than be parts changing until I find the problem. dodge dealer hear already cost me $820 by doing that and then I had my original ecm tested and it was fine. pulled the new one and it tested fine as well. figured id give this a chance.

Here is the connector pin chart for the ECM so you can run the wiring tests..

--->> Click Here to view <<---

Keep me posted and let me know if you have any additional questions...

Thank you,



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Customer: replied 8 months ago.
dude you are awesome. will let ya know what I find. I'll get back with ya in about an hour with the results. thanks for the diagrams. big help.

Sounds good, I'm here for a couple hours more tonight...

Thank you,


Customer: replied 8 months ago.
from the 50 pin schematic you sent me and the wire diagram I need to test wire for field gen. at pin 40 and gen. sensor wire at pin 28 to plug on alternator. looks pretty easy pin 7 is for fan clutch on my truck.

You need to be checking pins 28 and 40. Notice the legend on the wiring diagram. The diagram shows both the 5.9 and the 6.7 diagrams. On the 5.9 engine, it would be pin 7 instead of pin 40. on the diagram look slightly above where it shows pin 7, there it shows 6.7 as being pin 40.

Hope I didn't confuse you

Thank you,


Please remember to leave a rating or accept the answer if you have no further questions! If you are unable or cannot rate, please let me know!

Customer: replied 8 months ago.
will do. almost done.

sounds good.

Robert R and other Dodge Specialists are ready to help you

Thanks for the positive rating. How did it go? Did you find the problem?

Customer: replied 8 months ago.
brown, grey wire at pin 40 ran jumper up tp generator and voltage was good to go. break or fault in that wire. wire loomed new wire from repair to alt/generator and all is well. still leaving external in place on firewall as a just in case of roadside emergency, got the wire harness for that in storage under back seat. good thing I have had to make harnesses before or this could have been very expensing. Thanks for your help. figured this was the case, but the diagrams helped tremendously. I appreciate all your help.

No problem, glad I was able to help you get this figured out..

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