LOWnEASY

iTrader: (1)

02 4l80e was popping code for shift sol b. Changed the a and b solenoid and still has the same problem also if I go wot it takes 10+ seconds to kick down to second or first. how probable is it that the wire harness is bad? 4>3 kick down does fine
also manually shifting makes no difference still takes over 10 seconds to engage
I can Clear the coded and still pops solenoid b stuck. P0756. I can clear the code, take off from a stop and get all the way to 4th gear and aslong as I dont go back below 3rd it wont trigger, but as soon as it commands 2nd it throws the code. I can watch the scanner command 2nd when decelerating or when it needs to kick down but it takes 10+ seconds for it to get in 2nd and then throws the code.
I have not checked the pressure. Still need to find a pressure gauge

brandon6.0

iTrader: (32)

I think the harness are pretty common about being bad in the 80e. Did u have this issue just out the blue? Any tune changes?

LOWnEASY

iTrader: (1)

Just showed up out of the blue. No changes when it first presented its self. I have had the transmission out, got a 3400 stall, done dual feed, line to lube hole, new a and b solenoids, afl valve sleeved, VB cleaned and inspected by trans shop, new VB gaskets. every thing inspected and all looked well. I did unplug the harness from the case (external from internal harness) and cleaned with brake clean cause it did have some trans fluid in it but I'm yet to test it out due to starter problems.

MaroonMonsterLS1

I replied to your other thread over on performance trucks...if it's still throwing a code...and you can see it being commanded in the scanner...then you either need to start tracing the harness (power, grounds, and signal from PCM) or you need to start checking pressures.

Manual downshift making no changes leads me to believe there is a pressure issue or mechanical issue.
Start looking into the pressures and check out the 2-3 shift valve. If it's spring is broken or installed wrong, it won't stroke the valve and won't downshift to 2nd.

The interesting part of your trouble is that downshifts should be no-problem on a 4l80e. Because when in 3rd gear...you have 3 clutches applied. FWD, INT, and DIR.
for 2nd gear...you only have 2 clutches engaged. FWD and INT.

So for a 3-2 downshift...all you need to happen is for the direct clutch to dis-engage.

Things that can cause this are mechanical issues...wiring issues not signaling the 2-3 solenoid properly...or a faulty solenoid

performabuilt

iTrader: (25)

The PCM has no means to actually really know if the b solenoid is stuck it uses the engine RPM compared to the output speed to make this determination, I see if I understand correctly this started after a converter change, I would disable turn off that code first in tuning as it may just be setting a false code causing limp mode resulting in the downshift to second once limp mods is set,
Basically the converters stall is confusing the TCM .

LOWnEASY

iTrader: (1)

It started before the converter swap, along with the converter lockup engaging at idle and 4th gear neutrals. Line to lube hole and afl valve fixed those, it also got new pump gears, and front bump bushing i have already disabled the code, and it still does it. Also 2>1 seems a little sluggish as well

LOWnEASY

iTrader: (1)

Update: swapped in a known good valvebody with new valvebody gaskets and seperator plate along with new accumulator gasket. Still didnt solve the problem. one trans builder is telling me it could possibly be the boost valve?
I'm yet to get a pressure gauge that dosnt leak, although I did get to see the pressure at idle in park before shutting the truck off and it was at 190 psi.
what leads me to believe it isn't an electrielectrical problem, is both a and b solenoid need to be "off" for 2nd to engage. Going to try and get a gauge Friday and update again with the numbers.

LOWnEASY

iTrader: (1)

Update: finally got the pressure gauge on it, with trans harness unplugged from trans
Idle rpm is 850
P/N=80 psi at idle and 120psi at 2k rpm
R=60-80psi at idle and 240-250 at 2k rpm
1/2/3/D= 60-90 psi idle and 150-160 at 2k rpm.
with trans haness plugged in, all results are within ~10psi of the above pressures
also when I shift my rpms usually dip to 600 and the gauge goes down to 30 psi in all gear positions until rpms recover

My pressure gauge is too short to see the gauge wile going down the highway, but with the vehicle on Jack stands, selector in d, every time it shifts it drops to 30 then rebounds to the 90 range once the gear is engaged, as for my problem of the slow 3-2 kick down, it seems to be non existent wile on the Jack stands, all this done with light brake pressure to keep a little load on it.

LOWnEASY

iTrader: (1)

Any one have some ideas? Bad pump? Bad ecp? Internal cross leak? Any more test I can do?

Jays_SSZ28

iTrader: (2)

If you clear a code and it comes right back thats usually the problem area.

LOWnEASY

iTrader: (1)

The only code that was thrown was solenoid b stuck ON so I replaced both a and b solenoids and the problem was still there. In order for the 4l80e engage 2nd, both solenoids are to be off. it shifts fine from first (solenoid A ON, B OFF) to second but doesn't from 3rd to 2nd. For 3rd gear to work, solenoid a is off, and solenoid b is on, then when second is commanded solenoid b must turn off. This is what I dont get, is why isn't solenoid b shutting down when commanded (or the shift valve stroking like it should) First thought would be sticking or stuck shift valve, but it still doing it after a fresh valvebody install.

LOWnEASY

iTrader: (1)

Update, pulled the connector from the trans to see if ground was being switched off when commanded, with hpt. Scanner commanding second (both solenoids OFF) I still have ground on both solenoids causing them to be on. (10.8v)

Switch to command 1st (A on, B off) I have 11.9v at A and 10.8v at B.

Command 3rd (A off, B on) I have 10.8v at A and 11.9v at B.

command 4th (both A and B on) I have 11.9v at both.

Obviously theres a problem there, now to figure out if it's a short, ground problem or bad pcm.

Jays_SSZ28

iTrader: (2)

If you pulled the connector from the transmission and the solenoids still have ground That takes the vehicle wiring and PCM out of the picture.

But then again you go on to explain what voltage you get with each solenoid commanded so it's unclear when the trans got plugged back in.

LOWnEASY

iTrader: (1)

This is with the trans unplugged and testing the computer/engine side of the harness. I unpinned the A and B solenoid wires from the pcm conector, with the harness plugged back in to the trans, vehicle on Jack stands, I took a pice of wire and grounded it, connected the wire to the b solenoid to command 3rd gear, as soon as I disconnect the ground from the b solenoid it down shifts to second,

So its narrowed down to my segment swap failed, the pcm failed, or I have a ground problem some where.
I now have a thread going on hptuners forum since this seems to be a pcm/segment swap/tune problem

Thanks for every one that's chimed in (I'll update this with the problem for any future searchers)

LOWnEASY

iTrader: (1)

Turns out it was the computer, it wasnt shutting the ground off very quick at all causing the b solenoid to stay on for the 10-15 seconds. Swapped in new pcm and all is well.