21 Rd is a phenomenal trail. We hit it earlier this year. Is one of my new favorite trails
Looks like a really fun/cool trip
Looks like a really fun/cool trip
CK5
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One Piece at a Time: My 1985 Diesel Suburban
- Thread starter AgDieseler
- Start date
Roadkill moment. We’re in Holbrook, AZ with a 4L80E that refuses to shift past 2nd.
With the shifter in OD, the trans will shift to 2nd, and freewheel at the 2-3 shift. The PCS monitor, however, shows the trans shifting into 3rd and 4th while the engine free wheels. If the VSS reads low enough, the trans will return to 2nd, and we again have forward control.
With the shifter in D, the trans will shift into 2nd and hold that gear, not allowing any additional upshift. The PCS monitor continues to show 2nd as the current gear.
@Greg Ducato - any thoughts?
I data logged, but PCS is already closed. We found a trans shop that can test the switch and solenoids, and have checked into a backup hotel. I’ll hit it early with PCS tech in the am.
Living that old truck life.
David
With the shifter in OD, the trans will shift to 2nd, and freewheel at the 2-3 shift. The PCS monitor, however, shows the trans shifting into 3rd and 4th while the engine free wheels. If the VSS reads low enough, the trans will return to 2nd, and we again have forward control.
With the shifter in D, the trans will shift into 2nd and hold that gear, not allowing any additional upshift. The PCS monitor continues to show 2nd as the current gear.
@Greg Ducato - any thoughts?
I data logged, but PCS is already closed. We found a trans shop that can test the switch and solenoids, and have checked into a backup hotel. I’ll hit it early with PCS tech in the am.
Living that old truck life.
David
Hopefully you’re not dealing with a dead trans. Good luck!
Old trucks are awesome, they're so full of stories and character that you just can't get in a new ride. And sometimes they character it up right there on the highway and leave you with a story to tell.
The internet feels your pain, in meme form.
Fortunately, we have beer.
David
David
Hooray beer!
@willomet_motor_and_fab
Disaster averted!
Good morning, y’all.
We’re about to head to the transmission shop, and drop the pan to check A and B shift solenoids. After conferring with the resident expert (@Greg Ducato) and reviewing the datalog with PCS, that’s the next step.
We still have a strong reverse, first, and second - all good indications that this could be electromechanical. Certainly that’s what I’m hoping for.
David
We’re about to head to the transmission shop, and drop the pan to check A and B shift solenoids. After conferring with the resident expert (@Greg Ducato) and reviewing the datalog with PCS, that’s the next step.
We still have a strong reverse, first, and second - all good indications that this could be electromechanical. Certainly that’s what I’m hoping for.
David
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good luck
Bummer on the breakdown. Sounds like you got a good plan of attack. Good luck with the fixin and here's to an easy rest of the way home.
Solenoids A and B.
David
David
Done and back on the road?
Solenoids checked out. After checking continuities and forcing the trans to shift in manual mode, we found that the TCU has dropped an output driver, and we’re repinning the connector and reprogramming solenoid control so we can command a 2-3 and 3-4 upshift.
Just need to get home.
David
Just need to get home.
David
That's an out of the box way to go after it. Crossing fingers.
Abandoned repinning because we don’t have the exact AMP tool to do it, and without that it’s 50/50 whether we solve a problem or create a new one. PCS will have a new TCU here first thing tomorrow.
David
David
