4L80 No 1st Gear

[NickTransmissions]

That's not a question here, time is the constraint.

What's not the question?

Are you wanting to fix it yourself today?

 

[Supercharged111]

What's not the question?

Are you wanting to fix it yourself today?

No, was hoping for some long distance troubleshooting to reassure me I could deal with it on the other end just by dropping the pan and replacing some solenoids, but nothing electrical logically explains what's happening here. We're moving and this is really screwing things up and it's not the first thing that's gone wrong so extra frustrating.

 

[NickTransmissions]

No, was hoping for some long distance troubleshooting to reassure me I could deal with it on the other end just by dropping the pan and replacing some solenoids, but nothing electrical logically explains what's happening here. We're moving and this is really screwing things up and it's not the first thing that's gone wrong so extra frustrating.

Sorry to hear, man - I know that sucks....Here's a few things you can do in the meantime, if you have a couple hours to work on it:

1. Drop the pan, filter and valve body; remove the intermediate manual 2nd band servo to see if it's somehow wedged inboard into the case, applying the manual 2nd band or if the incorrect servo assembly was installed...If this is the situation, you'll start out in 2nd gear in all range settings, no matter what else is happening.

> 1999+ 4L80Es received an updated, wider int. band and longer servo pin..If the longer pin is mated with a first design band, it's possible it may be applied mechanically at all times (just a guess at this point)

2. Continuity test shift solenoids A & B - real long shot but perhaps one is dead or intermittently failing (not likely at all since you have 4th gear)

3. Remove the accumulator housing from the valve body (6 x 8mm long bolts) and, using a flat blade screw driver, work the 1-2 shift valve back and forth to see if it's stuck in the open position (i.e. where it's enabling 2nd clutch apply oil to enter the intermediate clutch circuit, causing 2nd gear starts

4. Air check the case with compressed air when the valve body is off - charge the low reverse band apply port (right next to the servo cover facing the worm tracks), intermediate clutch (center support feed bolt), direct clutch (hole to the left of the cs feed bolt) and high reverse (hole to the right of the cs feed bolt)...Another super long shot but maybe you'll notice anomalies though you won't be able to do anything about it without taking the trans out and tearing into it

All of the other 'no first gear' direct causes are inside the case...

 

[NickTransmissions]

No, was hoping for some long distance troubleshooting to reassure me I could deal with it on the other end just by dropping the pan and replacing some solenoids, but nothing electrical logically explains what's happening here. We're moving and this is really screwing things up and it's not the first thing that's gone wrong so extra frustrating.

Did you flush your lines and transmission cooler(s) prior to re-stabbing the transmission back into the truck?

 

[Supercharged111]

Did you flush your lines and transmission cooler(s) prior to re-stabbing the transmission back into the truck?

No, I didn't have a catastrophic failure. It was just quirky and I wanted it gone through. Fluid was clean and recent, though admittedly it would have been better to have flushed it. I dropped the truck back off with him and switched my vehicular configuration for this trip. Had first gear today until the trans hit 160.

 

[NickTransmissions]

No, I didn't have a catastrophic failure. It was just quirky and I wanted it gone through. Fluid was clean and recent, though admittedly it would have been better to have flushed it. I dropped the truck back off with him and switched my vehicular configuration for this trip. Had first gear today until the trans hit 160.

Interesting...I wonder if the trans builder did vacuum testing on the pump stator hydraulic circuits and those in the valve body as it sounds like the problem could also be in one of those places...I've not known a one-way clutch to work some of the time and not others...Anytime a transmission functions correctly when cold but not when at op temp is almost always worn or compromised seals/o-rings/sealing rings, applied elements and the like. It's usually not hard parts or electrical but stranger things have happened.

Let us know what he says...

 

[NickTransmissions]

No, I didn't have a catastrophic failure. It was just quirky and I wanted it gone through. Fluid was clean and recent, though admittedly it would have been better to have flushed it. I dropped the truck back off with him and switched my vehicular configuration for this trip. Had first gear today until the trans hit 160.

Super stupid question but are you 100% sure it has enough/proper amt of fluid?

Transmissions will exhibit odd behavior if low on fluid or has too much fluid

 

[Supercharged111]

Super stupid question but are you 100% sure it has enough/proper amt of fluid?

Transmissions will exhibit odd behavior if low on fluid or has too much fluid

I'm sure as of the last time I checked fluid level which was after running it up on the lift through all the gears and then after an actual test drive.

 

[NickTransmissions]

I'm sure as of the last time I checked fluid level which was after running it up on the lift through all the gears and then after an actual test drive.

Have you heard anything from your transmission builder?

 

[L31MaxExpress]

Failure with heat sounds electrical in nature. Think heat soaked starter or alternator here. Works when cold, fails when hot. I would think a roller clutch would just outright fail and be done once it failed. Been wrong before though. I just went into a 4L80E that would not shift above 2nd and it was corrected by addressing a sticking 2-3 shift valve, replacing the solenoids and internal harness. From memory 1-2 solenoid has to energize to have 1st gear and de-energize for 2nd gear and the shift valve has to move forward and away from the solenoid when it applies pressure to obtain 1st gear. If the electromagnetic coil in the solenoid is failing with heat you will not get 1st gear. In theory a failed solenoid would also make 4th disappear as well as it re-energizes 1-2 for 4th. Does it still have 4th gear after 1st disappears? Even after driving it 20+ miles around town up to as much as 60 mph in 2nd gear with the shifter in Drive the unit I was working on never set a single code.