D6N XL 590-9 247-9 Codes No Communication to ECM

[86Marlboro]

This is my first post, so give me some grace.

I have a 2015 D6N XL LGP S/N: PBA02881. Had a steering rotary motor go bad and changed it Saturday. Fixed my steering issue, while testing it out cut it off to talk to another guy with me. Went to start it back and it would crank but not start. Started throwing 590-9 and 247-9 codes and putting it in derate with forced stop on the dash. Never had this problem before, and the steering harness/system is completely independent from the ECM.

Can't connect ET to it because of abnormal data rate refresh, but on the dashboard in the cab it shows no communication to the ECM computer. Initially checked all of the fuses and breakers in the cab, they were all good none blown. I have checked grounds, on both canon plug and ECM plug. Checked power pins on both, switched and constant. All is good. Checked J1939 Continuity and resistnace as well as the CAT data link too.

I'm sure it's a rubbed wire grounded out or a simple fuse but not sure where to go moving forward.

Thanks for the help in advance!

 

[Nige]

You need an electrical schematic. Check your message inbox.

 

[Smilly107]

Did this get resolved? I have a D8T with the same codes no communication with engine ECM. I can crank and talk to implement and powertrain. Powers and grounds are good to the Engine ECU but I keep blowing the ECU fuse when the ignition is turned on. If I disconnect J1 from the ECU the fuse doesn’t blow. I feel like I’m dealing with a bad controller…

 

[86Marlboro]

Did this get resolved? I have a D8T with the same codes no communication with engine ECM. I can crank and talk to implement and powertrain. Powers and grounds are good to the Engine ECU but I keep blowing the ECU fuse when the ignition is turned on. If I disconnect J1 from the ECU the fuse doesn’t blow. I feel like I’m dealing with a bad controller…

Possibly, mine was a bad ground connection on the engine block. That fixed my issue.

I tell you what you can do and I have done in the past. Create a harness that will power up the Engine ECU by itself and then start the machine. You'll get some wonky codes because the CAN data is disconnected but you'll be able to defer if it's a bad ECU or bad harness in between.

I can try to grab some pictures of the harness I have. An old times fixed it up for me and gave it to me. It's super helpful, will get you out of a bind.

 

[Smilly107]

Interesting definitely share if you find it! With your test harness are you powering it straight from battery?


I need to take the scope out tomorrow and hook onto it to see if the wave forms are matching on the high and low.

 

[86Marlboro]

Interesting definitely share if you find it! With your test harness are you powering it straight from battery?


I need to take the scope out tomorrow and hook onto it to see if the wave forms are matching on the high and low.

Yes, with an on off switch. The sell some on the internet I'll try to find one so you'll have an idea. I'm sure there's a thread on here on how to make one. @Nige is probably the guy to have that thread ready.

 

[86Marlboro]

Interesting definitely share if you find it! With your test harness are you powering it straight from battery?


I need to take the scope out tomorrow and hook onto it to see if the wave forms are matching on the high and low.

Diagnostic Cable for Cat 70pin ECM's On Road and Industrial Harness | eBay

Programming the ECM when not on the truck. CAT cables can be used for a variety of purposes, including Compatible with NEXIQ, CATCOM3 and most other common adaptors that use a 9 pin OBD connector.

ebay.us

Here's one that's similar. Obviously nicer than mine but exact same concept.

 

[Nige]

What you can also try is find the switched power wires (there will likely be more than one) for the engine ECM and unpin them from the 70-pin connector. Then turn the key ON. Does the ECM fuse blow.? if it doesn’t then try re-pinning the power wires one at a time, testing after each one.

 

[Smilly107]

What you can also try is find the switched power wires (there will likely be more than one) for the engine ECM and unpin them from the 70-pin connector. Then turn the key ON. Does the ECM fuse blow.? if it doesn’t then try re-pinning the power wires one at a time, testing after each one.

I’ll go through the rest of the power wires. I did try isolating the key switch, but I disconnected it at the switch instead of the ECM, and the fuse still blew.

 

[Smilly107]

Before I go too far chasing wiring—does this still sound like an internal ECM short, or am I missing something?

I’ll be building a diag cable for the 70-pin Tomorrow but I went through it a bit more today. I’ve got no communication with the engine ECM, and the engine ECM fuse blows immediately any time the master is turned on (key position doesn’t matter).

What I’ve checked so far:

• J1 disconnected → fuse does NOT blow
• J1 connected → fuse blows instantly
• ~170kΩ to load side of fuse with J1 connected (master open), OL when disconnected
• All powers and grounds checked, no shorts found
• Verified to both positive and negative, circuits look clean
• 24V headlamp in place of fuse stays lit until J1 is unplugged or master is off

At this point I’m leaning ECM, unless something is back feeding through the CDL or I’m overlooking a common failure point but from a just a few google searches that ECU seems pretty common.

 

[DieselFit]

For what it's worth, I've had several ECM's on different machines that decided to get a short internally & blow fuses. The Cat dealer wasn't able to get anything from the old ECM s for configuration of the new ones.

 

[Simon C]

Before I go too far chasing wiring—does this still sound like an internal ECM short, or am I missing something?

I’ll be building a diag cable for the 70-pin Tomorrow but I went through it a bit more today. I’ve got no communication with the engine ECM, and the engine ECM fuse blows immediately any time the master is turned on (key position doesn’t matter).

What I’ve checked so far:

• J1 disconnected → fuse does NOT blow
• J1 connected → fuse blows instantly
• ~170kΩ to load side of fuse with J1 connected (master open), OL when disconnected
• All powers and grounds checked, no shorts found
• Verified to both positive and negative, circuits look clean
• 24V headlamp in place of fuse stays lit until J1 is unplugged or master is off

At this point I’m leaning ECM, unless something is back feeding through the CDL or I’m overlooking a common failure point but from a just a few google searches that ECU seems pretty common.

One wire grounding out will blow the fuse with a new or old computer. Paper, pen, one test at a time recorded so you have not missed one, or gamble and buy a new controller. Depends on money and time.
Simon C

 

[Smilly107]

Got a new ECU ordered, after connecting to it externally it would still blow the fuse. Internal short inside preventing any communicatio.

 

[Nige]

A shame when that happens but sometimes unavoidable. Please update when you get the replacement ECM installed.

By any chance has there been any welding done on the machine recently.?

 

[Simon C]

Got a new ECU ordered, after connecting to it externally it would still blow the fuse. Internal short inside preventing any communicatio.

So you did get the new ECM and it blew the fuse or you are wondering if it does blow the fuse the same as the old one.
Not sure what you meant. Was going to look at schematic but in post #3 says this communication problem was for a D8T Dozer. Totally different schematic. Will see what the outcome of this is.

Simon C

 

[Nige]

I read it as he bought a new ECM and when the old one was removed and connected to power externally it still blew the fuse. I may be wrong….

 

[Simon C]

Well if you are correct and the ECM was removed and hooked to external power on a bench and still blows the fuse, obviously it don't need to be hooked to harness. If that is so, my only wonder is if the harness could of taken out the computer.
Will have to wait and see.
Simon C