Move ECM to firewall or inside cab?

[the7t7]

Can anyone think of a reason why I shouldn’t move my ecm to inside the cab or the firewall? My engine harness is out of the truck getting improvements and I have a second wiring harness that I was using to help diagnose my ecm issue. I realized I could use the second harness to extend the length of my current one. There is room on the firewall under the brake master cylinder or in the cab under passenger dash. Only alterations besides splicing I can think of is I would have to make more twisted pairs of the water in fuel(not used) and oil pressure sensor wires since they are the shortest and exit right by ecm. There are also 2 shielded pairs (vp44 and Cummins bus). The Cummins bus (which the Quad uses) l wouldn’t have to extend. It would just end up in a different place. For the vp44 pair, I could just wire both harnesses wires end to end, and run one shield power wire to both shields. Only worry is if ecm is expecting a resistance range on that wire, since increasing the shield length would make the resistance go up. Ecm on the engine is obviously not the best place.

[Mopar1973Man]

Leave it on the block nothing gained by moving.

[dripley]

I would agree. A good while back placement of the ECM got a bad rap and blame for failures. To many folks out there with alot miles with the ECM on the block. Cant hurt to move it if you want, but I dont think there is anything to gain from it.

Edited January 17, 2020 by dripley

[kzimmer]

I think it's a great idea. The only reason it is where it is, is because Cummins supplied the motor as a running package. No one in their right mind would design it like that on purpose as a whole. The motor is its own entity, it's brain comes attached to it. 

 

The only thing I'd be concerned about is the quality of splices and shielding on any analog sensor wiring, and communication bus wiring. If you don't have confidence in that part, I wouldn't do it. If you do, I say go for it.

[AH64ID]

My initial thought is can the wiring handle the added distance without voltage issues? As sensitive as ECM's are to voltage a huge increase in wiring could lead to plenty of issues. 

 

The ECM is designed to be on the block, so I am not sure you will have any appreciable benefits from moving it... and it may cause issues. 

[Bullet]

I think it's a bad design in the first place and definitely should be somewhere else...preferably in a cooler, dryer and less vibrative (new word) environment.  However, being as bad as DC current is at losing resistance on longer runs I would be afraid lengthen any wires to/from it.

 

There have been several examples of trouble free operation for hundreds of thousands of miles in its current location (me included).  But there have also been many ECM failures too.  Might there have been much fewer if it were originally located in a more comfortable environment?  Hmm... 

Edited January 17, 2020 by Bullet

[Mopar1973Man]

Better look at other Cummins engines most all of them are on the block. All the Cummins engines used in Dodge and Ram truck are on the side of the engine block. Heat, vibration never been an issue. 

 

Biggest issue is the AC noise from the alternator and the ground wiring which there is a W-T ground wire mod. I'm at 407k miles and still rolling. @dripley is nearly 500k miles and still rolling. 

Edited January 17, 2020 by Mopar1973Man

[the7t7]

Those are some good opinions and that’s what I asked for. I’m leaning towards keeping it on the engine. I don’t think the extra distance would cause any issues but I can’t be sure. Since I was just hunting down an ecm failure issue, I don’t want to add any more variables to sort through in case it doesn’t start with the new ecm and vp44 (which I’m mostly sure is the culprit since old one had a bad psg). It would add around 50 new splices that could be a source for failure. I did add some rubber bushings and some reflective insulation on back side of new ecm just to help a little with heat and vibration.

[wil440]

Most all large diesels I see ( up to 32litre) ecm is on the block but everyone is fuel cooled  even before aftertreatment which do run very hot

[AH64ID]

6 hours ago, wil440 said:

Most all large diesels I see ( up to 32litre) ecm is on the block but everyone is fuel cooled  even before aftertreatment which do run very hot

 

I have heard the fuel:air heat exchanger in the ECM go both ways... to heat the fuel, or to cool the ECM. Granted it can do both, but what is the primary goal?

[kzimmer]

11 hours ago, AH64ID said:

My initial thought is can the wiring handle the added distance without voltage issues?

 

Yes.

 

11 hours ago, AH64ID said:

As sensitive as ECM's are to voltage a huge increase in wiring could lead to plenty of issues. 

 

A few feet of wire added can't hurt anything. The only thing that can hurt it is a bad splice/termination or improper shielding causing noise.

 

10 hours ago, Bullet said:

I think it's a bad design in the first place and definitely should be somewhere else...preferably in a cooler, dryer and less vibrative (new word) environment. 

 

Agreed.

 

10 hours ago, Bullet said:

Might there have been much fewer if it were originally located in a more comfortable environment?

 

It's an interesting thought.

 

10 hours ago, Mopar1973Man said:

All the Cummins engines used in Dodge and Ram truck are on the side of the engine block.

 

Yep. Again, like I said, because the engine is supplied as a package. Just because it's designed that way doesn't mean it's the best way for longevity. 

 

10 hours ago, Mopar1973Man said:

Heat, vibration never been an issue. 

 

For anyone? Ever? There is no possible way that you could ever know this. This is a made-up statistic.

 

9 hours ago, the7t7 said:

It would add around 50 new splices that could be a source for failure.

 

Absolutely. That's why I mentioned it; you would want absolute confidence in your splices and good wiring practice. Without that, it's risky.

[wil440]

40 minutes ago, AH64ID said:

 

I have heard the fuel:air heat exchanger in the ECM go both ways... to heat the fuel, or to cool the ECM. Granted it can do both, but what is the primary goal?

Only to cool the ecm as far as I know as fuel in modern engines passes through the head in a common passageway anyway so it picks up more than enough heat but I only do large diesels now, well Cat C7 up to C32, sililar size volve,komatsu etc

[int3man]

Well if you want to do something nice for your ECM, next time the batteries are disconnected, remove it and clean all the ground connections, mounting points and the electrical plugs.  Just a suggestion.

 

Michael :- )

[the7t7]

8 hours ago, int3man said:

Well if you want to do something nice for your ECM, next time the batteries are disconnected, remove it and clean all the ground connections, mounting points and the electrical plugs.  Just a suggestion.

 

Michael :- )

Yes that’s the plan plus a bit more. My truck had fried it’s second ecm and nothing obvious was the culprit. (I have a recent post about the details). I had already done the w-t mod. So out came the wiring harness and the vp44. The pump was working but since I had to do a tappet cover gasket,  the pump had to come out. I sent it to Oregon Fuel Injection to test. Ended up it had a rare issue where it had a bad chip in the psg with codes there but still continued to work. The wiring harness was fine, so I think the psg was the culprit and took out the ecm on the data link wires. While everything is apart, I’m improving the crappy factory splices in the harness and putting new connectors on all the weathered pdc and engine grounds and battery cables.

Edited January 18, 2020 by the7t7
Grammar

[Great work!]

The wires that have any significant  current are the positive  non switched wires and the lift pump. If the lift pump is upgraded with it's own power and relay like many aftermarket pumps then the wire size is not an issue 

[Mopar1973Man]

ECM does not ground through the body. ECM is grounded to the passenger side battery directly. Hence the WT ground wire mod,