2013 NAG1 transmission will not engage any gears

[PapaGut]

I've run into some trouble in my 13 Wrangler where it slipped out of gear, then shortly afterward refuses to go into any gear forward or reverse at all. Its behaving as if it's in neutral. Its a NAG1 transmission. Its not the shift linkage, that's secure, not fluid - levels are good. I did find historical codes: P0732 and P2784, which made me suspect sensors, so the contact plate has been replaced. Fluid is clear, no debris in pan, filter is seated. Wiring appears to be in good condition.

The torque converter was just replaced, by me - went in fine, and car was driving nicely with no issues till now.

It's got me stumped, the only thing i'm hanging onto at the moment is that since it will not go into gear, the fluid appears to be high, but I can't get it into neutral, which would be needed to engage the pump and have a realistic fluid level to test.

Perhaps the pump is not engaging?

I do have a scanner and can pull live information from the transmission. Does anyone have suggestions on where I might start to troubleshoot this further?

Cheers, mark

 

[tJKrider]

I've run into some trouble in my 13 Wrangler where it slipped out of gear, then shortly afterward refuses to go into any gear forward or reverse at all. Its behaving as if it's in neutral. Its a NAG1 transmission. Its not the shift linkage, that's secure, not fluid - levels are good. I did find historical codes: P0732 and P2784, which made me suspect sensors, so the contact plate has been replaced. Fluid is clear, no debris in pan, filter is seated. Wiring appears to be in good condition.

The torque converter was just replaced, by me - went in fine, and car was driving nicely with no issues till now.

It's got me stumped, the only thing i'm hanging onto at the moment is that since it will not go into gear, the fluid appears to be high, but I can't get it into neutral, which would be needed to engage the pump and have a realistic fluid level to test.

Perhaps the pump is not engaging?

I do have a scanner and can pull live information from the transmission. Does anyone have suggestions on where I might start to troubleshoot this further?

Cheers, mark

Maybe a longshot but could it be the brake on/off switch? If that failed the trans would not get the proper signal to allow movement of the shift lever.

 

[PapaGut]

Maybe a longshot but could it be the brake on/off switch? If that failed the trans would not get the proper signal to allow movement of the shift lever.

Thanks - I can move the shift lever, and can hear the shift lock disengage when I touch the brake. Dash shows it going into D or R as well.

 

[tJKrider]

Thanks - I can move the shift lever, and can hear the shift lock disengage when I touch the brake. Dash shows it going into D or R as well.

Got it. I was thinking that you couldn't move the lever as well... I'm not that familiar with the Jeep/Daimler trans. On Some Ford vehicles there is a solenoid separate from the shift lock. I know I'm reaching but thought I would just throw some ideas out there... Good luck!

 

[PapaGut]

So after some time with the battery disconnected and cables touching, there are no active codes, just the same two historical ones, no change in the transmission - no gears at all. To further diagnose I removed the return line at the transmission, and with the engine running and in neutral, there is zero fluid flowing. So I'm highly suspicious of the pump at this point. That seems to be consistent with what I experienced I think as well. My next step will be to open it up and check the engagement of the torque converter to the pump.

 

[PapaGut]

All solved now, but i'll post the details here should anyone run into something similar - classic error. I pulled the return line for the transmission and ran it in neutral to verify if fluid was circulating at all - not a drop. That suggested the pump squarely as the culprit. Short version is that when I previously replaced the torque converter, which by the way solved my initial issue which was the Jeep going into gear from park so aggressively that it would stall the engine until it warmed up, I failed to seat it correctly. When reattaching the transmission to the engine with the TC not fully seated, I managed to break the two small tabs off that drive the gear in the transmission pump. This did not come to mind right away as the Jeep drove fine for a 1000 km or so, but I am thinking now that this was just dumb luck. Maybe a tiny piece of the tabs remained, enough to drive the pump for a while. When I took the TC back out, there the tabs were. Seems from the shops I spoke to, it's a rookie error for sure: TC should slide onto the shaft, then a second click as it seats on the tabs correctly. The wisdom also bestowed on me is that when you reattach the transmission to the engine, the TC should be slightly away from the flexplate, enough that it spins freely, and that the bolts should pull the TC and flexplate together.

Here's a couple of images of an intact pump beside my "modified" one, and the tiny broken tabs that disabled the whole car.

 

[tJKrider]

All solved now, but i'll post the details here should anyone run into something similar - classic error. I pulled the return line for the transmission and ran it in neutral to verify if fluid was circulating at all - not a drop. That suggested the pump squarely as the culprit. Short version is that when I previously replaced the torque converter, which by the way solved my initial issue which was the Jeep going into gear from park so aggressively that it would stall the engine until it warmed up, I failed to seat it correctly. When reattaching the transmission to the engine with the TC not fully seated, I managed to break the two small tabs off that drive the gear in the transmission pump. This did not come to mind right away as the Jeep drove fine for a 1000 km or so, but I am thinking now that this was just dumb luck. Maybe a tiny piece of the tabs remained, enough to drive the pump for a while. When I took the TC back out, there the tabs were. Seems from the shops I spoke to, it's a rookie error for sure: TC should slide onto the shaft, then a second click as it seats on the tabs correctly. The wisdom also bestowed on me is that when you reattach the transmission to the engine, the TC should be slightly away from the flexplate, enough that it spins freely, and that the bolts should pull the TC and flexplate together.

Here's a couple of images of an intact pump beside my "modified" one, and the tiny broken tabs that disabled the whole car.

View attachment 125824

View attachment 125825

Congrats! Glad you were able to solve it. Appreciate the details so, hopefully, we don't follow the same path...