NEED HELP 04 4L60e Shift Issues

[Flarph]

This is a new to me 04 trailblazer i6. Mileage is 151000 and the transmission is supposedly at 60k. Purchased it a couple of months ago and it has more or less ran fine with the exception of some of the common HVAC gremlins and it even performed great towing my 2200# popup trailer a couple hours out for a camping trip in August. No performance issues noticed until the issue cropped up.

The Issue:
About a minute after performing a spirited pull from stop to highway speed the vehicle seemed to have shifted into and stuck in neutral. I was able to limp it off of the highway by putting it into 4hi and got it into a parking lot. After being towed it would not move in 4hi or 2 hi. I saw a post where a user had tracked the neutral issue down to a clogged transmission filter so I replaced that and viola! It shifts now. Sort of. It will come out of neutral and go into reverse which seems to operate normally however in 1,3,D it will only get to a couple of miles in hour, as in 2-5MPH before all power is gone and revs just = noise. I suspect this is because it is actually just starting in 1st. 2nd gear seems to operate just fine and the engine sounds normal. Note that this is all when manually shifting to these gears. It will not shift automatically any more.

I read up on a lot of the common issues with these and can’t find anything that sounds right. There are no engine codes, so maybe it’s a clutch? I am not sure if that would cause it to not auto shift. I am thinking that this is a problem with the shift solenoids and would like to see what everyone's opinion is on this before I commit to dropping the transmission pan again. The fluid was fairly dark with just a faint pink hue when I replaced the filter. I also have a code for the encoder motor that pops up in 4wd however I don't think that would have anything to do with this.

Let me know what you think!

Thanks

 

[Flarph]

This is the closest thing I could find to how it is behaving.
“”
12. Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it’s moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: A wiring problem from PCM to transmission or PCM.
“”
I haven’t been able to try to see if switching to D after speeding up in second will allow it to go 3-4. It starting in 4 could make a lot of sense since I don’t think 1 is so short that it would be topping out at 5MPH. It is a new vehicle to me though so really I don’t know.

 

[Reprise]

I do think the 1-2 solenoid (aka: 'A') could be a factor, here.

The nice thing is, they're interchangeable - so you could actually swap them, and see if the problem follows, before spending the $ for the replacement. But that requires a second pan drop, of course. They don't cost a fortune, so if you wanted to just get a new one, you'd save some time / effort.

If you find dirt / residue on them, that may be why the one wasn't working. In that case, clean them, as it may restore their functionality (brake cleaner is fine.)

The solenoids are on the 'front' edge of the valve body (facing forward, toward the engine), and you should be able to get them out without touching the VB otherwise. You will need a pick tool, which you can also use to gently lift on the clip ends for the wire harness. These can turn brittle, so use care when lifting / pulling back.

Remove the filter, carefully disconnect the harness, and then use the pick tool to remove the wire clip holding the solenoid in (there's a little elongated slot that the clip goes into.)

If the ends of the clip are facing down, spin them around so that they're facing up, and you can then pull downward to release them through the slot.

Examine the o-rings after you pull them out, too - make sure there's no cracking / breakage. No, I don't know the size for replacements, but they should be a fairly standard size. Use EPDM or, even better, Viton -- those types are resilient to fluids.

Also, I'd take some brake cleaner and spray throughout the VB, if you found the solenoids to be excessively dirty. Wear safety glasses for this, of course.

Use an inch-pound torque wrench on the pan bolts, and tighten them in at least two steps to the proper torque. Alternate sides when doing this. Don't forget to put the filter back in, first!

 

[TJBaker57]

I will say right off that I have never worked on an automatic transmission internally. But I have some knowledge of the PIDs and such displayed by a Tech 2. Like the Fluid Pressure switch. So a question here for those that know..... If a solenoid is not working right would that not show in the output of the fluid pressure switch? The switch is acted upon by fluid pressure and the ouput can indicate the various positions of 1st, 2nd, 3rd, drive, and reverse. It cannot differentiate between Park and Neutral however.

 

[Flarph]

Okay, I will replace the solenoids this weekend and update on how its running. Thank you!

 

[Flarph]

Well, I replaced the A, B, 3-2 downshift, and PWM solenoid and still have the same issue. The only thing I did not change was the pressure control solenoid because it was blocked by the 1-2 accumulator and I did not have a gasket and did not want to risk it. The wiring harness also looked okay.

Unfortunately it is experiencing the same behavior as before. Not sure where to go from here.

 

[Mike534x]

Was the fluid burnt? If its just free revving in the other gears they could be toast....because if it got a little better with a new filter then there is definitely something up with that tranny.

 

[6716]

When I started having issues with my transmission I messed around with the valve body and got a little more life out of it but I think it kinda just postponed the inevitable rebuild. I chose to pull the transmission myself and give it to a rebuilder thinking I would save some money. By the time I installed the torque converter wrong and had to get that fixed again, I probably spent as much money as taking it to a shop and having them do all the work. Plus it took me a lot longer to do it.

 

[TJBaker57]

IF you do take it for a rebuild, AND you travel a lot, consider the warranty. I had my Yukon 4l60e rebuilt in northern Indiana while travelling. Three months later it failed and the warranty was essentially worthless as I was over a thousand miles from there. Had to pay again to have it pulled and rebuilt again!

 

[Flarph]

Alright, looks like a tranny shop is in my future. Thanks for the help diagnosing.

 

[Reprise]

2nd gear seems to operate just fine and the engine sounds normal. Note that this is all when manually shifting to these gears. It will not shift automatically any more.

You mentioned you had no codes. We'll assume you have a decent scan tool; if not, you can try another, and see if you have any codes not present previously.

Check the following fuses in your underhood box:
#10 - Powertrain Control Module 'B'
#25 - Automatic Shift Lock Control System (this is the brake <> shifter interlock; doubtful)
#28 - Powertrain Control Module 1
#29 - Oxygen Sensor (there's a reason for this one, so check it)

In addition, there's an auxiliary fuse box under the rear D/S seat. None of the fuses / relays here should affect the trans until 2005 (the TCM module fuse); it's #35 and should be blank in your truck. But check through these, too. There are no PCM fuses in this box, but there are a few Body Control Module fuses here.

If you find any of these blown, replace with the proper amperage fuse and test. If it blows again, check to see if you have any issues like an O2 sensor harness grounding (maybe touching exhaust & burning through the insulation, etc.) The wiring schematics supposedly show shared connections between the trans and a couple of things like O2 sensors (the schematics are available on our site; easiest way is to look for the sig area in any of Mooseman's posts)

Since yours is an '04, you don't have the separate Transmission Control Module (TCM) mounted on the side of the trans. The PCM controls both the engine and trans.

If all your fuses / relays look OK, then the only things I can think of from here are:
- 1-2 accumulator might be cracked or spring broken
- Forward accumulator issue (same as above)
- Forward clutch gone
- Forward sprag issue (but I don't think you'd have second, here

The accumulators are in the VB; it appears you're fairly savvy, mechanically, so you could check these if you wished. But the VB has to come out for both.

For the other two, the trans comes out (e.g.; it's rebuild time). Looks from your last post like you're heading this way, anyway. Good luck; hopefully you can find the issue.

A rebuild will cost between $1200-1800 or so, depending on the area you're in, rebuilder you use.
(with this option, you should get some sort of warranty)
A replacement from a junkyard will run $500-800 (again, depending on source)
Cheaper, but you don't know what condition it was in before you got it (other than the yard maybe saying it was working before they dismantled it)

 

[gmcman]

When you said you had to use 4HI to limp it off the road, would it only drive in 4HI?

If that's the case, perhaps the issue is in the transfer case. I thought that regardless of the transfer case's state of health, you would always have 2HI and could lose 4WD, but not sure on that.

You also mentioned a code for the encoder motor. Maybe the transfer case is getting stuck in Neutral, which is a position for the transfer case if the vehicle needs to be towed with the rear wheels on the ground.

Neutral is not visible on the selector switch, it's a spring loaded position beyond the 4LO position.

The "N" light will illuminate when in Neutral.

 

[Flarph]

Checked the fuses and they are all in good shape. I may try replacing the encoder motor before I go any further since its been having issues anyway to see it it is playing a role before I go any further. I will have to shelf this for a bit until I have some more troubleshooting cash at hand though. Ill update if I run across a solution.