Community Forums

hrt · 08-16-2020, 12:56 PM

I have a 2017 Dutch Star on freightliner XCR450. Been having some low DEF warnings, despite tank being between 1/2 full and full. First time I had this, Freightliner support suggested there was some crystalization in the lines, and I should keep driving until it went out. I did, it did. But since then it has been coming back. Yesterday it added 'very low def' and engine torque derate.

When I talked to Freightliner this morning, at the end of the call he suggested that there are a few fuses or circuits for the DEF system in the power distribution module (PDM), and I am still subject to the recall for that, and seemed to suggest that it might be related. Does anyone have diagrams showing the location and layout of the PDM, or have any information about whether that could be the cause? It's not too long a way to the nearest dealer, but I'm not excited about driving there in limp mode if I can possibly avoid it.

Dutch Star Don · 08-16-2020, 01:24 PM

On my 2014 DS, I diagrammed the fuses that are in the PDM. There is one DEF Gauge fuse and one DEF Heater fuse. I haven't diagrammed the 2019 PDM yet, but I'm guessing it will have the same fuses.

That PDM powers....Tag, Towing- RH, LH, Markers, Reverse, and Ignition (I'm guessing hot line to trailer plug), Air dryer, Fuel Heater, ABS, ATD, Fan Clutch, DEF Gauge, DEF Line heater.

I will find out in two weeks, on our next trip, but I think my failed module was affecting my fan clutch, forcing it to high. I was also losing A/C at the dash.

hrt · 08-16-2020, 01:52 PM

Thanks - yeah, I wonder if that's my problem. The dash gauge (the four light bars) is right about the DEF quantity. So if the 'DEF gauge' fuse in the PDM is for a separate gauge for the engine, that could be the cause

Rd1 · 08-16-2020, 02:21 PM

Quote:

Originally Posted by Dutch Star Don

.....(I'm guessing hot line to trailer plug),.....

on XCPs the hot line to the trailer is certainly the case.
On the original PDM (Prior to 18v recall), did not have any issues with the DEF. Since 18v, I had a couple of times issues with DEF, but it cleared out. have not experienced that since.

Bobschle · 08-16-2020, 10:19 PM

I had similar problems. It turned out to be a bad DEF header. Replacing it was an endeavor

hrt · 08-17-2020, 01:14 PM

Quote:

Originally Posted by Bobschle

I had similar problems. It turned out to be a bad DEF header. Replacing it was an endeavor

Is the DEF header the whole thing that sits on the def canister and has 4 wires/tubes coming out of it?

GoRed · 08-20-2020, 07:46 PM

My Spartan chassis 2020 Dutch Star with 5K miles gave me DEF concentration level low with emission check engine light on. Checked with Cummins and Spartan. This code will NOT put your engine into limp mode. I finished driving it home from vacation and took it to my Cummings service center and they replaced the sensor on the DEF head. Have only drove it 100 miles since replaced and no codes.

hrt · 08-20-2020, 11:20 PM

Quote:

Originally Posted by Bobschle

I had similar problems. It turned out to be a bad DEF header. Replacing it was an endeavor

Oh yeah - the Cummins roadside tech and I were looking at what that would take. Did you drop the whole def tank down?

hrt · 08-23-2020, 01:28 PM

Quote:

Originally Posted by Bobschle

I had similar problems. It turned out to be a bad DEF header. Replacing it was an endeavor

How did you go about it? Do you have any pictures? It seems on my coach as though there'd be no way to get the thing out without raising the whole coach.

I'd hoped to have freightliner service do it, but then I'd have to leave the coach with them for several days while it waits in line. We full-time, so that's not a good option.

hrt · 11-12-2020, 11:23 AM

Quote:

Originally Posted by Bobschle

I had similar problems. It turned out to be a bad DEF header. Replacing it was an endeavor

Do you have any pictures or instructions based on your experience?

I just had a mobile tech out here who basically said he couldn't do it, because there was no way he could do it without pulling the tank out and it would have to be laid sideways to do so. Which is also what it had looked like to me, which is why i wanted a pro to do it

hrt · 11-12-2020, 11:26 AM

Quote:

Originally Posted by Dutch Star Don

On my 2014 DS, I diagrammed the fuses that are in the PDM. There is one DEF Gauge fuse and one DEF Heater fuse. I haven't diagrammed the 2019 PDM yet, but I'm guessing it will have the same fuses.

That PDM powers....Tag, Towing- RH, LH, Markers, Reverse, and Ignition (I'm guessing hot line to trailer plug), Air dryer, Fuel Heater, ABS, ATD, Fan Clutch, DEF Gauge, DEF Line heater.

I will find out in two weeks, on our next trip, but I think my failed module was affecting my fan clutch, forcing it to high. I was also losing A/C at the dash.

The mobile tech who was out here to replace the DEF header, said he could not replace the PDM because it requires doing a software update he didn't have the tools for. I had previously thought the PDM was just a simple replacement. Did you replace it yourself?

(While the mobile tech could not replace the def header in the field, based on his - and my previous - failed attempts to reset the codes so i could drive to the shop, it really seems likely that the PDM is the actual root of my problem)

Rd1 · 11-12-2020, 02:35 PM

The PDM recall, is just replacing the PDM box. I have had 2 different PDM recalls and niether required any software update. Just remove the old box, beware, some of the wires behind it are hot. then move all the fuses and relays from the old to the new box

hrt · 11-13-2020, 08:02 AM

Quote:

Originally Posted by Rd1

The PDM recall, is just replacing the PDM box. I have had 2 different PDM recalls and niether required any software update. Just remove the old box, beware, some of the wires behind it are hot. then move all the fuses and relays from the old to the new box

Thanks! I think I'll just order one and do it myself then.

This whole situation has gotten absurd.

ptw · 11-15-2020, 08:40 AM

Do you keep your DEF tank full? Just curious since we had the same problem two years ago. Since then I fill the DEF tank when we get to our final destination and always store the coach with the DEF tank full. We have not had the problem since.

Don't know if this is why the problem stopped. Someone on this group suggested to do that and it seems to be working for us. I also bought a refractometer to test the DEF, all tests have been good.

See attached, not sure if this is the right part number for you.