Has anyone ever experienced a GPS unit causing the CEL to illuminate? I've got a 2016 KW T-800 that seems to be very sensitive to GPS units. We plug the unit into the data port, and within a few minutes the CEL lights up. One time the error code was for a DEF dosing sensor of some sort, the next time the error was for the fuel level sensor. If we unplug the GPS unit and clear the error, everything is fine. If we plug it back in, the error comes back and the CEL illuminates again. We've tried two different brands of GPS units, and both cause issues. We have the same GPS unit in a newer truck and it experiences no problems at all. I'm wondering if the 2016 era KW ECM is susceptible to this for some reason.
Has anyone else seen this happen?
GPS Unit causing Check Engine Light on 2016 KW T-800
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by TankerJim, Dec 31, 2020.
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Right around 2016 is when trucks started coming out with higher data speeds datalinks. If you have a black coloured datalink plug in the truck, then it is older, slower 250K baud rate datalink. Green plugs are the newer high speed datalinks at 500K. Most modules do work with backwards compatibility, other times it causes problems like this. So check for this possible conflict.
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Yup....your introducing something to the CAN line that the truck doesnt recognise or like. Most "reporting tools" take a snapshot or sample the data and will cause problems to the info on the line.
Moral of the story....dont plug in things to your data ports that are not supposed to be there.....if you want telemetry order it with the truck that way its engineered to be there. -
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All reporting tools, other than real time, are "snap shot tools" and they randomly sample "all data" on the CAN line, they do not filter, the filtering is done by the receiving software you run on your PC [or other device] or imbedded in the GPS EPROM......so in other words, its just a logger.
I can't tell you how many times per week i deal with this kind of cr*p...........so in order to be more helpful to you.....
You failed to mention if this was a new unit you were adding to the trucks or if it already had the units and "all of a sudden" it started making the trucks act up so i'm going to assume that it is a new addition.
You have a compatibility issue as it works on one but not the other.....so lets start with the basics:
1- What CAN protocol is that truck running? 250k or 500k [green or black 9 pin connector?
2- Did you check the pin out of the device "bus" connector verse the truck to make sure they are correct?
3- When the codes appear what is the "reported" possible fault correction [ie: short to ground, open load etc].
4- Is their a "generational" difference between the 2016/17 and the newer trucks [ so did they change ECMs, CAN arrangement, etc]spsauerland and AModelCat Thank this. -
In addition to what @6cuda6 mentioned, does this same GPS unit run fine on a different truck?
I have had issues with some CAN modules for aftermarket accessories spam up the datalink when they fail/become corrupted. I actually had it out on the phone with the tech support guy one day when he claimed it cannot happen. He didn't really have an answer when I told him it works just fine when I replace the module and when the old one gets plugged back in it spams up the datalink again.spsauerland and 6cuda6 Thank this. -
I suggest you start with wiring the unit to the truck as Paccar instructions tell you to, instead of how the GPS unit does.
Every plug and play unit out there will tell you to just plug and play inline at the 9 pin diagnostic connector. This is where 90% of the problems occur.
The incapatabilty lies with the changes to the baud rate from 17-19 as others have suggested. Pin locations changed at the 9 pin and then went back at 2020.
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Just want to echo this quote, since I can only thank it once:
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