Emergency DEF bypass

[WinePress]

I saw a post, can’t find it now, that linked to a website that laid out a kit to build that would bypass the sensor issues. Can someone direct me to this? I’d like to have one in case I get stranded on my journey to Hawaii.
Thanks in advance……

 

[CaptainGizmo]

To do this right, it’s not cheap. Additionally, the components can be hard to obtain currently.

Depending on your DEF system, I may be able to you a DEF Head Emulator from Custom Coach Products.

Feel free to drop me a DM and I’ll get info from you.

 

[redbaron]

defsim.myervin.com

 

[Rich W.]

RB’s link is correct ( DEF Sensor Simulator ), its about $150 to build, but it will only work on 2016 and later chassis (my 2016 coach is on a 2015 chassis so not compatible) and as designed, it is only compatible with Spartan chassis coaches and some Tiffin (Powerglide chassis?) models with solid-state DEF level, temp, and quality sensors.

To make it work with 2016 and later Freightliner coaches you have to acquire the correct 4-pin (CAN-bus) connector (now also detailed on the website).

Pre-2016 Freightliner coaches have a float for sensing DEF level and the signal can be emulated with the correct resistor, but I don’t have that information readily available. Easy to figure out though (see TSB below).

So while an excellent adjunct for compatible units, its pretty limited. It also only overrides the sensors in the tank, so you still have to run DEF or you will get SPN codes from your SCR telling you your NOX levels are too high, and still be derated.

Also it appears that as of around late 2020 Freightliner DEF headers (TE connectivity) nearly eliminated the false low DEF failures. DEF heads from Shaw Development used in Spartan and Powerglide chassis are said to be more reliable as of Gen 7 but that remains to be seen.

So to get a more specific answer on what you can do both as preventative measures, and for contingencies, list your coach chassis year, make, and model. But don’t just buy the parts and build the DSS without confirming that it will work for you.

There’s a lot you can do on your own to increase the reliability of your coach and your confidence in your emissions system. I’ve had three parts failures resulting in derates, but my last trip (7700 miles) was completely emissions-trouble free. Had my share of other issues, but not a peep from the emissions side.

This TSB: https://static.nhtsa.gov/odi/tsbs/2013/SB-10054667-8295.pdf has a lot of useful information on keeping your system working and correcting problems, and includes the correct resistance reading for pre-2016 DEF level sensors if you want to go that route.

 

[WinePress]

Thanks for everyone’s input. I’m on a FL chassis so I will do more research on the adaptability from the Spartan connector to the FL. I did disconnect, clean and reconnect all the connections, including the PCM. Problem cleared, but I would like to be proactive with a solution to solve a potential non drive issue.