Transmission issue

[Mezz519]

Hello everyone, and thank you Rawze for the invite.

2017 Peterbilt 579 with 16 speed automatic eaton. ISX15.
Recently I started having a very random issue with my Pete.
It started at a truck stop in the fuel isle. I came to a stop and put my tranny into neutral and set my brakes like I always do. After fueling I go to start my truck and the transmission gear select box shows service light flashing and on dash showing N for neutral then switching to F. Back and forth. After a few attempts it started.

It didn’t do it again for a while. Then at the booth at the border in Detroit/Windsor it did it again. I almost got towed but last minute got it started.

Then on my way back into USA again at the booth same thing happened. Officer gave me 25 minutes to get it started and it just wouldn’t start. Constantly flashing service and showing F/N on dash where the gear number usually is.
This time the tow did come and towed me out costing me 1400 USD. While out of the booth the truck started.

Has anyone had this issue before and where should I start diagnostics. Friend of mine said the harness would be a good start but with so many things possibly affecting it I was wondering if someone here had a better idea.

Thanks in advance.

[Mezz519]

I would also like to add that it seems to happen mostly at the booth at the border. Not sure if it’s pure unlucky timing or if it’s because the way we come to a stop there. Slowly driving into the booth, putting it in neutral and not releasing the brakes.. and is there a way to bypass it in case it happens again before I get it fixed. I’m almost home!

[Rawze]

how old is the truck?.. tranny?. Some history, etc?.

I do not own or work on auto-s#itters trannies ..but there are some basic things to check for...

Make sure the battery connection going from the batteries to the XY shifter are not loose or corroded. If it is not getting full electrical power to that shifter then it will act up like that.

Maybe others will chime in with better advice.

[ktblogistics]

had very similar issiue ( exacly same sysmptoms ) with endurance transmission, it was damaged wiring at transmission plug, when you disconnect it it is really difficult to pull it down for inspection but when i removed some zipties i was able to pull it down enough to have a closer look, had rubbed wires that caused intermittent loss of communication, wiring rubbed against plastic cover at 90 degree bend,
plug looks non serviceable but you can disassembly the plug and remove pins and change wiring, i replaced the total of 4 wires there,

[Mezz519]

Thank you for the replies.
Truck is 2017 with roughly 800k miles.
I did read about XY shifter as well.
Will start with wiring. Feel free to add any other suggestions.

[Btech]

Being it flashes fault on the display means there is a code stored in the transmission control module, you should be able to get a code on the gear indicator by starting with the key on, turn it off and back on 2x to get active codes, 4x to get stored codes, and 6x to clear codes.
these codes can give you a good idea of where to start, the 2 digit codes you get this way can be somewhat broad sometimes but its better than nothing.

[david24]

(03-02-2024 )Mezz519 Wrote:  Hello everyone, and thank you Rawze for the invite.

2017 Peterbilt 579 with 16 speed automatic eaton. ISX15.
Recently I started having a very random issue with my Pete.
It started at a truck stop in the fuel isle. I came to a stop and put my tranny into neutral and set my brakes like I always do. After fueling I go to start my truck and the transmission gear select box shows service light flashing and on dash showing N for neutral then switching to F. Back and forth. After a few attempts it started.

It didn’t do it again for a while. Then at the booth at the border in Detroit/Windsor it did it again. I almost got towed but last minute got it started.

Then on my way back into USA again at the booth same thing happened. Officer gave me 25 minutes to get it started and it just wouldn’t start. Constantly flashing service and showing F/N on dash where the gear number usually is.
This time the tow did come and towed me out costing me 1400 USD. While out of the booth the truck started.

Has anyone had this issue before and where should I start diagnostics. Friend of mine said the harness would be a good start but with so many things possibly affecting it I was wondering if someone here had a better idea.

Thanks in advance.

I had that issue a while ago. Had to replace clutch and the electronic clutch actuator

[Pete379]

I have seen issues like this with the ultra shift transmissions in a kw truck that has the stalk shifter. Our issue was in the stalk shifter itself. The problem was intermittent and we had a heck of a time figuring it out.

To sum up months of headaches we finally figured out that when the 3rd stage Jake was used on the stalk shifter it would short out the stalk control. Truck would still drive fine and shift fine but the stalk was dead. You could not shift manually and that included putting it in neutral or reverse. The truck would stay in drive and when the parking brake was pulled it would put it into auto neutral. If a driver did not notice the shifter was shorted out say for example pulling up to fuel pump throwing stalk into neutral and turning truck off it would be shutting off in gear and wouldn’t want to start back up. Dash would show F in gear display.

A few minutes with the battery cables disconnected and everything would reset and truck would start up and operate fine

We replaced the shifter, which was not cheap by any means, and the problem was fixed. If you have a stalk shifter they are known to have issues I would consider finding one that you know works and try switching them