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.

  1. TankerJim

    TankerJim Bobtail Member

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    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?
     
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  3. Heavyd

    Heavyd Road Train Member

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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.
     
  4. flood

    flood Road Train Member

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    My question....

    What gps do you have that required to plug into the truck
     
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  5. TankerJim

    TankerJim Bobtail Member

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    We've tried several GPS units. Azuga and Geotab are a few. Along with reporting GPS position, they also provide remote telemetry such as on-board error code information, so if a check engine light comes on, we see the error code right away at the office. It's pretty helpful, up until the time we started seeing the #### check engine light come on and it seems to be tied to the fact that the GPS unit is plugged in. We tried unplugging the unit, and the problem went away. The odd thing is that we've run these GPS units for years without any problem. Now, all of a sudden two of our trucks will throw a random error code as soon as we plug in the GPS units. Some of our newer units are running the same GPS units with no problems. Seems to effect our 2016/2017 Kenworths, but not the newer ones.
     
  6. 6cuda6

    6cuda6 Light Load Member

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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.
     
  7. TankerJim

    TankerJim Bobtail Member

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    Actually, all modern PACCAR products are designed especially for this. There is a body-builder data port installed in each of the trucks at the factory for just this reason. Most GPS units are fairly cheap and do not talk to the bus at all anyway. They just sit there and listen, filter out the garbage and report back the essential data via their Bluetooth or cellular connection. Believe me, if the factory offered a decent OEM telemetry unit, we would all be buying it, but they don't. Even their limited function telemetry unit is a joke. It doesn't provide even a fraction of the data that is need. That's why the majority of the major trucking companies do it this way. Sadly, PACCAR can barely support their own products. PACCAR is decades behind in technology and doesn't want to risk selling something that might be outdated before it is released, so they have historically relied on the aftermarket environment for the high tech. It's easier for them to point the finger at someone else. There is no way they're going to add high-tech to the list of things they do poorly. They don't even offer TPMS in most of their vehicles. For christsakes, I have a 15 year old pickup that has TPMS. Anyhow, thanks for your comments. They were of no help whatsoever. Happy New Year.
     
  8. 6cuda6

    6cuda6 Light Load Member

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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]
     
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  9. AModelCat

    AModelCat Road Train Member

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    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.
     
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  10. Goodysnap

    Goodysnap Road Train Member

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    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.

    These people are taking thier own time to try and help resolve your issues. If you dont like the responses a simple "thank you" will suffice. Otherwise go ask for free help somewhere else......
     
  11. God prefers Diesels

    God prefers Diesels Road Train Member

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    Wow.

    Just want to echo this quote, since I can only thank it once:
     
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