Hello all,

I have a 2001 4l80e that I just rebuilt. It has 220K or so on it, rebuilt a couple months ago by me.

I've been having issues with it. It skips 2nd gear, gives me a p0752 (shift solenoid A stuck on) DTC and runs warm (around 170-200). I tried everything I could find on the internet and this forum, and finally discovered the AFL valve wear issues and associated problems. I had the AFL bore drilled out by a local shop, and I installed the sonnax kit yesterday.

For the most part, it works great now. The problem is that it will randomly skip 2nd and throw the p0752 code (as opposed to ALWAYS skipping 2nd) The biggest issue is that now my 4th doesn't work. I have never had this issue before, it has always been a strong engagement and held well with no issues. Now, it shifts to 4th, and then acts like its in neutral. Shifting to 3rd and it works perfect, will even lock the torque converter after a little bit.

As far as the 2nd issue, I know that 2nd works. (manually shifting 1-2-3 and it works fine, and downshifting 3-2 works fine) but for some reason it skips. Mind you its not always skipping anymore like it used to, it just does everyonce and a while.

This is a bone stock 80e with the sonnax boost valve and AFL fix. Rebuilt using the raybestos super kit. I'm running valvoline Dex/merc fluid, which I just changed yesterday (I even blew the lines and cooler out with compressed air. I added about 7.5 qts which the dipstick confirms is the right amount) There are no special tunes or anything. I'm at my wits end here, so I really hope someone has some insight.

Thanks!!

 

Could it be related to your band and/or servo?

I lost 2nd and 4th in my 4L60E and after doing research I found that the culprit was likely a worn or broken band. Have you checked the end play of the servo?

 

The rear band on the 80e controls 1st and reverse. There is another band that is applied for 2nd, but like I said, it works sometimes and manually.

 

This is an 80e not a 60e. Your experience with the band in a 60 is totally irrelevant to the 80e

the 80e has 2 bands. A low/reverse band...I hope I don't have to explain when that comes on, but I'll do it anyway...This band is used to keep the low roller sprag from overrunning. You need the band to engage reverse OR to provide engine braking when in Manual 1st

Then there is the intermediate band. This provides engine braking in 2nd by also not allowing a sprag to overrun. This time the intermediate sprag.

As for trying to identify OP's issue, can you tell us if you have hooked up a scanner, or a pressure gauge. The scanner will tell you if it is commanding 2nd gear and the trans just wont do it, or if the computer just never even commands it and it goes straight to 3rd because that's what the computer tells it to do.
Are there any codes? Bad speed sensors can cause some funky action.

The pressure gauge will help determine if the trans seems healthy inside.

 

Thanks for the reply!

I have an actron CP9690 scanner. If anyone could tell me how to see what the computer is up to with that particular scanner, that would be awesome. However, I don't think that my actron is extremely comprehensive.

Do you have a recommendation for a lower-priced gauge? It sounds like this may be my next step. The pump looked great inside when i had it apart. There was no wear on the gears or races, and the bushings were replaced along with the boost valve.


I do have some more info for you, too. I tried putting the truck in tow/haul mode. When I did that 4th sort of worked. Basically, you can go 40 mph at 2000 RPM in tow/haul as opposed to no motion without it. One other funny thing that i noticed is that in tow/haul, starting from a dead stop, it absolutely refuses to shift. It just revs up higher and higher. Revving up and letting your foot off the gas to try to make it shift will only make it fell like its stuck between gears. Turning off tow/haul will make it shift like usual. I never had this issue before the rebuild, btw.

 

The first hit on amazon for transmission pressure gauge (red case) has worked great for people in the past. Its roughly $30
OTC has a nicer kit for about 65 that has 0-100 and 0-300 psi gauges.
tow haul mode really bumps line pressure...that may be why you're getting 4th a little bit before it slips.
Not personally familiar with your scanner, sorry...but I *think* with Actron you go to the view data or live data tab, and scroll until you see what you need. The PID you are going to want is probably called "trans current gear" or "current gear" "commanded gear" etc...something like that.
FYI the commanded gear usually leads the actual shift by a little bit, so don't let that surprise you.
Lastly, if you find a PID on the scanner for line pressure...ignore it. That is commanded pressure in the AFL circuit...not at all indicative of the actual line pressure

 

Thanks for the recommendation. I tried with my scanner to look at the datastream for any transmission PIDs. I also looked in the manual, but apparently my scanner doesn't have capability for transmission PIDs. By the way, I believe that my scanner is basically a Bosch 1200 with a different name on it, and runs bosch software.

Not sure if this is related or not, but there is no transmission module showing up on the list of available modules. The p0752 has always been under the 'engine' module when clearing it, so maybe they are integrated somehow...?

Anyway, I ordered the gauge from amazon- Thanks for the suggestion! Since my scanner isn't really suited for trans work (lack of PID capability), do you have a recommendation for a relatively inexpensive one? i would love a tech 2 or the autoenginuity system but the cost is pretty high. I would also like to stay away from PC based systems if at all possible.

 

I have used a BafX scanner with the Dash Command Pro app.
The scanner itself is about $25
The app is like 5-10 bucks then you can buy the "extended parameters" set of PID's for your car for another $10 (fyi if you buy the parameters for prettymuch any 411 pcm car it will work...you'll get a message that says "vin doesn't match selected car" but it doesnt matter...you'll still see the data you want)
I have personally used this to monitor trans temp, commanded gear, and TCC status. Easiest way to do it is to just set up a gauge panel in the app for all your trans parameters.

 

Thanks for the info! I looked into the scanner you suggested, and it looks like it'll do the trick.

This morning i had a short spell were it was working correctly. As in shifting 1-2-3, and then it would shift to 4 for a few seconds and then fall out, engage, and fall out, and then back to 'problem mode'. A few miles later, it did the same thing, except it held for a few hundred yards. During that time, it operated at the proper RPM/MPH ratio (about 1500 rpm for 45-50 mph) and had proper lockup. Temp was at 145 or so.

I love magic fixes, but I don't believe in magic, so there must be something strange going on. Maybe some assembly lube hasn't dissolved yet? I used some to hold the checkballs in place when reinstalling the valve body, and some in the 2nd servo bore to hold it in, as well as a little on the manual valve. I used standard blue assmblee goo. I have checked the grounds and repaired the ground strap that goes between the hood and firewall, the others look alright.

Truck is a 2001 silverado 2500HD 4x4 shortbed crew cab with a 6.0 vortec and 4l80e, by the way.

 

Asemblee goo will be well melted at 145. Don't think that's your issue

 

OK, so I hooked up that app and scanner like you recommend. I drove it a little this morning, and got some interesting data.

The computer is commanding all gears like it should, but the trans is not physically shifting. When it commands 2nd, it continues in 1st until the computer commands 3rd, and then it shifts fine with a small flair. If the computer commands 2nd and you manually shift to 2nd at the same time, it shifts perfect.

On the tow/haul mode thing, I found that in drive with tow/haul ON, the computer commands 3rd. This tells me that 4th definitely doesn't work at all, which is weird because it worked great before the AFL fix. Also, it will not shift 1-2 in tow/haul, even though it commands 2nd.

After the truck cools off i'm going to hook up a gauge and see whats going on there.

 

Time to update this thread!

I got the gauge mentioned above, but unfortunately the gauge doesn't work. I ended up grabbing a nice 0-300 oil-filled one from napa that can be used with the hoses and adapters in the kit.

Anywho, here are the results. please excuse my crappy handwriting;



According to my check chart, this looks about right. The chart says to use a 400 psi gauge, and that reverse max pressure should be 330 MAX. My gauge only goes to 300, so obviously I pegged the gauge at WOT in reverse.

whats next? Thanks!!!

 

bump.

 

Annd bump again. i really need this this going again so if anyone has any insight, that would be great.