my 4l80 was rebuilt less than a year ago. Ip went out and i quit driving it. while moving it around in the yard noticed no reverse. no pops or nothing. well now i got the ip fixed and figured oh well ill just drive it anyway. Now overdrive is out also. did a band check in low gear and truck still compression breaks so im sure band is good. I think its solenoid or valve body related but not sure any help would be appreciated

 

Pull the OBDII trouble codes first, see what you get (note the 1-2 shift solenoid column in the chart, I'm thinking "something" will show up in the DTC's).

If no codes, then check chart:



Other "no reverse" conditions:

REVERSE
NO REVERSE OR SLIPS IN REVERSE
• Low and Reverse Band Anchor Pin (81)
– Broken or mis-positioned
• Center Support (640)
– Broken
– Leaking at case
• Center Support Seal (639)
– Leaking
• Center Support Bolt (25)
– Loose or broken
– Feed hole is blocked
• Low and Reverse Band Servo Piston (65)
– Binding in case
• Low and Reverse Band Servo Piston Seal (66)
– Leaking, damaged or worn
• Low and Reverse Band Servo Gasket (63)
– Damaged or displaced
• Low and Reverse Band Servo Cover (62)
– Damaged
• #7 Ball Check Valve
– Stuck
– Missing
• #11 Ball Check Valve
– Stuck
– Missing
• Direct Clutch Piston (619)
– Leaking
• Direct Clutch Piston Seals (620, 621 & 622)
– Leaking
• Direct Clutch Ball Check Valve (537)
– Leaking

Lots of things it could be, figuring out what it is might be a bit more difficult.

That comes from the GM powertrain 4L80E manual by the way. I've got a copy here.

One last thing; please don't do a "band check" again.

That's a good way to "eff it up" even more.....

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Saw your post on another forum.

P0756 Shift solenoid B.

First, make sure the electrical connector on the side of the transmission doesn't have transmission fluid inside the connector. They have been known to weep and cause all kinds of weird problems.

If that's good then:

4L80E Shift Solenoid " B "

Or if your transmission is still under warranty, back to the rebuilder I would go....

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I should add it's worth you while to meter the solenoid before you start ripping things apart.

Info can be found here:

http://static.summitracing.com/globa...tci-377000.pdf

 

Does shift solenoid b sound like the of issue and low reverse solenoid or pin sound like my reverse problem. Trans fluid looks ok

 

I have no idea what you were trying to say there....

 

changed out solenoid b. Fluid looked good. Some very fine particles near magnet. Im hoping its something stupid with overdrive. Reverse im pretty sure is due to apply pin. driving it recently I have noticed no compression braking in 2nd and 3rd (goes down to idle as soon as i let off accelerator) I had od before I changed out ip. Could that be something