jfw432

I have an 02 4L60E transmission that I rebuilt maybe 2000 miles ago attached to a 99 5.3L engine. I drove around today about 100 miles and everything felt normal. After taking a break, I started my engine back up and it felt like it wasn't going into gear since I'm used to the vehicle lurching a bit as the transmission loads up the driveline. It feels more like a new Honda going into gear with just the slightest notion of an rpm drop and a hint of driveline load. This happens in both 1st and Reverse but 1st and reverse seem to work fine now... I actually had to give the vehicle a little gas to get moving initially rather than just letting off the brake and having it roll though. 1st and Rev seem to be doing better now but the lurch when shifting is still not there.

When I got onto the road, it became very obvious something was really wrong. The vehicle shifted into 2nd and just revved like crazy. I can't tell if it's slipping or if the gear is just gone. When this happens, I can smell something that smells like hot fluid but it's hard to describe. Regardless of the what the smell is, it's only present when revving in 2nd. When I let off, it shifts into 3rd and seems normal except that it won't go into 4th. I had to limp home about 55 miles using only 1st and 3rd gear.

Fluid level is fine and the fluid doesn't appear to be burned. I'm guessing this is either a 2-4 servo or 2-4 band but is there a way to check either of those without yanking the transmission? If it sounds like something else, I'm all ears.

MaroonMonsterLS1

Have you done a pressure test?

It does sound like the 2-4 band is toast.
Drop the pan and have a look

jfw432

I'd have to borrow or build a pressure tester. What would I be looking for with it though? I looked up normal pressures once before but I'm not sure I know what a pressure that's too high or too low would be telling me.

PBA

You most likely lost the 2-4 band, and probably the reverse/input drum with it. Do the pressure check as suggested, and solve this first. DO NOT let it slip anymore, (just in case you have not burned the band), you don't want to finish it off.

jfw432

Thanks. I did everything I could to prevent slipping. As I said above though... What am I looking for on the pressure test? I'm not against it at all but I don't know what I'm looking for in terms of pressures. Looking at the pressure check procedure, acceptable range is between 55-189psi in P, D, and N while Reverse is 64-324psi. However, without a scan tool to give me the pressure control solenoid amperage, those ranges are extremely broad and I don't know what I'm looking for or what a bad reading would even tell me.

jfw432

So I haven’t had a chance to drop the pan or get a pressure check done but I did get a hold of a friends scantool. Some of these are redundant and others may be mis-represented but it gives a bit more information. I also discovered that it’s not really 2nd and 4th gear that are missing. Feels more like 1st and 4th are missing which could be more like an electrical problem rather than the band.

Here are the codes that I’ve gotten but not all of them show up every time I check. I’ve just compiled them all into one list.

P0756 2-3 shift solenoid (no 1st or 2nd)
P0751 1-2 shift solenoid (no 1st or 4th)
P0742 TCC stuck on (I’ve known this one for a while but it only lasts for ¼ mile and then it’s fine so I’ve been putting it off)
P0740 TCC solenoid circuit (probably the same as above)
P0713 Trans fluid temp sensor high voltage
P0706 Trans range switch (This appears to just be something that doesn’t make sense to the computer like driving in park or going too fast in a gear that can’t go that fast…might be the shift switch)
P1810 Trans pressure valve position switch
P1870 Trans slipping

mrvedit

With that many transmission codes, check that the trans connector is fully snapped into the trans. Perhaps it came loose.
You might be starting in "limp mode" which is 3rd gear with a 4L60E. (2nd gear with a 4L80E).

But to answer your other questions:
You can buy a trans pressure gauge on Amazon for $44; search for "ATD-5550"; it has a 5ft hose which lets you even hang it from your outside mirror while driving. It connects to the trans on the driver's side access port.
Generally you can do a stationary test. At idle the pressure should be in the 50-75psi range. When you blip the throttle it should jump into the 200 psi range. And it Reverse, it should be in the 150 psi range.

If the band is worn out, the servo end play will be excessive. You can check the servo end play by pressing with a crowbar on the servo cover while holding a ruler nearby. The spec is .075 (1/16) to .125" (1/8"). Somewhere around .175 the band may start slipping and by .250" it won't even engage at all. Usually 2nd gear is lost first, but some people report that 4th is lost first.
I have documented how to lengthen the servo pin to get a bit more life out of the trans and several members reported success:
Lengthened Servo Pin:
https://ls1tech.com/forums/automatic...t-trouble.html
https://ls1tech.com/forums/automatic...-gear-all.html
https://ls1tech.com/forums/automatic...ckup-help.html
Worked:
https://ls1tech.com/forums/automatic...cond-only.html
https://ls1tech.com/forums/automatic...e-2-fixed.html
https://ls1tech.com/forums/automatic...-4th-gear.html
https://ls1tech.com/forums/automatic...nd-only-2.html

Please keep us updated on progress or lack thereof.

jfw432

Well the new shift solenoids, wiring harness, TCC solenoid, pressure switch, and force motor were all swapped with zero change. I'm sure the new TCC did something but I won't know if that worked until the vehicle has been sitting for several days. I don't see any problems with connectors or damaged wires going to the trans or neutral safety switch. I measured the servo end play several times since it's tough to get that measurement and got everything between about 0.075" and 0.110" so it looks all of the different ways I checked appear in spec.

The problem is definitely losing 1st and 4th though. 2nd is fine until it gets to the shift point and then it either slips or just revs freely. Once I let off the throttle, it'll shift into 3rd and will act fine in that gear under normal driving. It'll shift back into 2nd when braking but downshifting with lots of throttle will cause it slip or rev freely (hard to tell what it's doing).

One thing that is super weird is my ECU. Using a scan tool, my engine throws so many codes at all times. A normal CEL code reader won't pick up on any of them and the CEL on the dash don't come on even though it works but the scantool will basically throw every code you can think of. Erase them all and without even starting the engine codes like engine misfire, come back even though the engine runs perfectly. All the sensors that have varying voltage readouts will throw both a high and low voltage code as well.

jfw432

Additional information that may be relevant that a friend had me check. Reverse does seem to slip but it works.

MaroonMonsterLS1

Just tear it apart. It needs a rebuild. Anything else is more than likely just pissing money in the wind at this point.

jfw432

That's basically where I am. I'm going to do a pressure check this afternoon and if I can't determine anything with that, I'll be pulling the tranny and digging in. I'm just at a complete loss on what could've worn out after less than 2k miles of light driving. Doesn't meet the criteria of any hard parts being broken from what I can tell.

jfw432

Line pressure was around 50- 60psi no matter what I did or what gear I was in. Reverse is clearly slipping because the vehicle will not move backwards uphill...only on flat ground.

I'm pulling the trans now so we'll see what is found but I'm not sure if I'll get to teardown tonight.

jfw432

I quit tonight just short of pulling the piston and output shaft. Everything internally is perfect so far.

I'm out of ideas short of only the transmission side of the ECU crapping out which is seems super unlikely...

jfw432

Anyone? I'm about to throw this thing off a cliff and just buy a re-manufactured trans.

The valve body is clean, new solenoids didn't fix the issue, all the clutches and tolerances are good inside the trans, all of the planetary gears are solid, and the pump isn't cracked or leaking. I thought about the torque converter being the problem but that wouldn't really explain why it still pulls great in 2nd and 3rd and the revs/mph match exactly what they should be in those gears.

01ssreda4

iTrader: (96)

Code 756 will start in 2nd, shift to 3rd and thats it. You will have no 1st, 4th or lockup. High stall converters throw this code often if not turned off. Not saying your trans is not internally fuckered, but those codes will cause some of the conditions you are experiencing.

mrvedit

Normally I would suggest checking line pressure with the trans connector disconnected as this will cause max line pressure, but since you are slipping in Reverse, it does sound like you have an internal pressure problem. (The Reverse circuit presses on the boost valve to increase line pressure.)

Since you are reporting really low pressure, and the typical "minimum" pressure, my guess is that there is a problem with the boost valve (which increases the minimum pressure) and you can check that without removing the trans.
==> Make sure you have the correct boost valve installed. It should be 1.907" long; if using e.g. the Transgo boost valve, make sure the aluminum spacer is on it. (The late model short boost valve is 1.810" long.) And confirm that the boost valve is not sticking in its bore and not overly loose.

If you are willing to try one more thing, remove just the pump and examine it for the following problems:
1. Make sure the yellow pump screen is installed on the side of the pump. (Part # 231 and #232 on page 106 of the ATSG manual)
2. Make sure the o-ring (#201) is installed under the pump slide seal (#202).
3. Check for any other obvious problems in the pump area.

These are the most common pump problems people have reported here.

jfw432

Thanks for the help. I was optimistic but the boost valve sleeve is the 1.907" version and slides nice and smooth with both springs inside. I checked orientation, condition, and proper configuration of all of the valve body shuttle valves and springs to make sure I didn't have a brain fart when I rebuilt it and can't find anything wrong there either. There is a spring that's stuck inside of the valve bores but it offers spring tension on the valve so hard to tell if it's causing any problems.

I don't have the ATSG manual. I did find one online but it doesn't line up with the same page numbers and doesn't have a section on the pump that I can cross reference. However, I do have the screen on the pump and the giant o-ring around the main body is intact and seals well.

mrvedit

Glad you checked the boost valve; sorry that my best guess wasn't it.
The o-ring I was referring to sits under the pump slide; it acts as both a seal and a spring to force the metal seal against the slide. I have no idea how much pressure would be lost with a broken or missing o-ring here, but it is a part that could easily be missed.

jfw432

No problem. Thanks for trying. I'll research a little to better understand what the pump slide and o ring are before I completely give up.

jfw432

Turns out the transmission had nothing to do with this problem. Got a rebuilt transmission and it's doing the same thing.

Guess that leaves me with the ECU that somehow is messed up in the transmission but not the engine. I went over all of the electrical connectors and can't find any issues.