transmission issue troubleshooting

[uhlhazard]

The vacuum switch has a ball that protrudes just beneath the surface of the 233 tcase, the electronic switch protrudes a good 3/8 inch beneath. The threads are the same but after looking inside of the 241, the arm that hits the switch would never reach it.

There is almost no information available online for the swap I'm looking for so I'm guessing its not done or there is some fundamental issue. I know a lot of guys hate electronic tcases and vacuum actuators. I like them personally and will stick with the 233 if the 241 swap won't work.

Ooh I also forgot to mention. I read on zr2.net that you can swap in the 6 pinion planetary from the 4 series into a 3 series BUT evidently they changed the design of the gears 95/on and my 4 series is a 96 with my 3 series a 94 so I didn't want to risk it.

[buddrow]

Buddrow, on the log file, do I need to log it with a "trans" adx file or does that matter? - I assume it does matter.... There are two different trans adx files if so... so I am not sure which one to use really. This is for $0D 6395 PCM. I'll try to figure it out but in case you have a comment off-hand... thought I'd ask.

Kevin,

Log with the trans adx. http://www.tunerpro.net/download/dat...rans1_v250.adx

Buddrow

[buddrow]

The vacuum switch has a ball that protrudes just beneath the surface of the 233 tcase, the electronic switch protrudes a good 3/8 inch beneath. The threads are the same but after looking inside of the 241, the arm that hits the switch would never reach it.

There is almost no information available online for the swap I'm looking for so I'm guessing its not done or there is some fundamental issue. I know a lot of guys hate electronic tcases and vacuum actuators. I like them personally and will stick with the 233 if the 241 swap won't work.

Ooh I also forgot to mention. I read on zr2.net that you can swap in the 6 pinion planetary from the 4 series into a 3 series BUT evidently they changed the design of the gears 95/on and my 4 series is a 96 with my 3 series a 94 so I didn't want to risk it.

Look at the full size dodge trucks, they used vacuum acutated diffs. maybe a vac switch from one will have enough reach. Also, check the driveshaft yoke and make sure it is the same spline as well. Some were 27 spline, some 31 spline.

Buddrow

[kevinvinv]

Hey Buddrow, sounds like you have had a long day. What were you coding for? Curious.

Attached is my log.

Basically this is the sequence:

Truck stopped,
accelerate up to 4th gear,
TCC Locks
Cruise for a few seconds,
Let off gas (note TPS)
shift to D3
RPM DECREASES slightly ??
Now shift do D2
RPM stays low
Slowly pulse the throttle (note RPM increasing and decreasing with TPS as I gently pump the pedal)
Finally give the pedal a pretty good press and then let off
You will notice the RPM stays high but the TPS goes back low again... indicating that the tranny is now engine braking.

I cant seem to find what field shows if the PCM is commanding this behavior or not... sure welcome your thoughts... later

[buddrow]

Kevin, Looked at your log after making a new dash in the adx with a few pertinent parameters. Transmission is doing what its told to do. Ive attached the adx so you can see what I'm seeing. Open the Diag Dash(drop down menu upper left corner of Main dash).

While playing back the log, watch the current gear, it is the commanded gear from the pcm. Notice the "Drive 2", Drive 3", & "Drive 4" params, this is position of the shift lever.

Buddrow

[kevinvinv]

buddrow, thanks for that. Cant look at it until tonight. Can I clarify something?

The "current gear" -- is that as reported by the transmission then? I do think I recall seeing that "current gear" followed my shift lever position nicely. It is just that when I went to D2, the dang thing didn't shift down until I rev'd the motor up to about 2500RPM. You can see that in my original log if you watch the RPM towards the end. When it goes up and stays up... that is b/c the engine braking started to happen.

Looking forward to checking out your adx tonight.

BTW- do you know how I can find out which things the QDM controls in this PCM (6395) ? I still am worried b/c the datastream is showing QDM faults (although there is no trouble code posted).

[buddrow]

Kevin,

I'm not sure, as 1project2many and Billy Graves posted, what they actually connect to or where. All I know from my exp with the code is that it seemed to always correlate to a loss of power/short to ground in the circuit. It may be time to find a good used pcm to try out if the circuits from the pcm to the trans check out OK. I think the last time I saw a ODM code was in an early 90's front wheel drive car but that's been a minute lol.

As for "my" adx, I just used the existing adx and added another dash screen with only the items I would use in such a case as yours to demonstrate how the computer shows the commanded gear versus what the trans is actually doing. The current gear status is the commanded gear from the pcm, When you pull the manual lever down to 2nd above a certain mph it will the trans will freewheel until a certain rpm is reached and then it "latches up" into that gear. same for first. It does this to prevent overrevving the engine.

Buddrow

[kevinvinv]

Cool... thanks... will look more tonight when I get a minute.

One question... lets say I want to probe the wires in the trans harness. Is that do-able with a meter or a test light? I know the pins are labeled like 1-2 clutch and 3-4 clutch or somthing like that... how do I make sense of this? Is it something like when the line is pulled to ground, the shift happens or something?

I called the place I got the tranny from today over in Chicago- he thinks the overrun clutch drum is bad... but before I pull this sucker out for the second time- I want to make sure there is nothing electrical jacked up....

Thanks!

[lionelhutz]

I can't see the solenoids being bad if it's up-shifting fine. The 4L60e uses 2 solenoids to select the 4 forward gears. Solenoid A is energized for 1st and 4th and solenoid B is energized for 1st and 2nd. If you lose solenoid A you can only get 2nd and 3rd gears. If you lose solenoid B you can only get 3rd and 4th gears.

If you unplugged the transmission connector or blew the transmission fuse it would default to 3rd without any power to the solenoids. Kind of a limp-home mode.

The transmission has power applied to the solenoids and then the PCM grounds the solenoid to complete the circuit.

[buddrow]

I can't see the solenoids being bad if it's up-shifting fine. The 4L60e uses 2 solenoids to select the 4 forward gears. Solenoid A is energized for 1st and 4th and solenoid B is energized for 1st and 2nd. If you lose solenoid A you can only get 2nd and 3rd gears. If you lose solenoid B you can only get 3rd and 4th gears.

If you unplugged the transmission connector or blew the transmission fuse it would default to 3rd without any power to the solenoids. Kind of a limp-home mode.

The transmission has power applied to the solenoids and then the PCM grounds the solenoid to complete the circuit.

If solenoid B fails you get 1st and 4th, Solenoid A fails, 2nd and 3rd only. Sequence from 1st thru 4th Solenoid A/B = on/on, off/on, off/off, on/off.

You don't see the overrun clutch fail very often, like maybe 1/1000 units and it's usually accompanied by the forward clutch and input sprag failure as well.

Buddrow

[buddrow]

Cool... thanks... will look more tonight when I get a minute.

One question... lets say I want to probe the wires in the trans harness. Is that do-able with a meter or a test light? I know the pins are labeled like 1-2 clutch and 3-4 clutch or somthing like that... how do I make sense of this? Is it something like when the line is pulled to ground, the shift happens or something?

I called the place I got the tranny from today over in Chicago- he thinks the overrun clutch drum is bad... but before I pull this sucker out for the second time- I want to make sure there is nothing electrical jacked up....

Thanks!

Yes you can probe the wires in the trans harness with either a test light or DVOM or analog meter. They aren't labelled as 1-2 or 3-4 shift but as Power, Sol A, SOL, B, TCC, TCC PWM, MPS, etc. Power wires(there are 2) are Pink or Pink/Black.

Power is supplied at Key On, pcm controls the ground circuit to the respective solenoid.

If you're in doubt as the the trans operation, take it to a reputable trans shop that does free or low cost diag. I wouldn't tell them anything other the actual problem you are concerned with. I don't trust anyone no matter how nice they seem, Ive worked around way too many crooks.

If you wanna pull it out and tear into the trans I'll walk you through the process, it's not hard.

Buddrow

[lionelhutz]

If solenoid B fails you get 1st and 4th, Solenoid A fails, 2nd and 3rd only. Sequence from 1st thru 4th Solenoid A/B = on/on, off/on, off/off, on/off.

Ummm, look at the 2 "off" gears for solenoid B - 3rd and 4th??

You get 3rd when the controller fails to energize any solenoids (goes to a limp-home mode) so 1 of the choices for both solenoids failing has to be 3rd.

[kevinvinv]

OK thanks. Where can I get a pinout of the connector at the trans end

-- strike that... I'll just find it with google. Thanks (too early for me yet!!) :)

[buddrow]

Ummm, look at the 2 "off" gears for solenoid B - 3rd and 4th??

You get 3rd when the controller fails to energize any solenoids (goes to a limp-home mode) so 1 of the choices for both solenoids failing has to be 3rd.

You are correct but, the trans will never default to 3rd and 4th, only 3rd. If sol B has failed off but sol A is still functioning you will have 1st and 4th, no 2nd or 3rd. If solenoid A fails you will have 2nd and 3rd, no 1st or 4th, since sol B is still turning on and off allowing for the gear change. If you look at the sol state chart, you will see that in 1st, both sol A and sol B are on. In 2nd, sol A if off, B is on. In 3rd, both solenoids are off, in 4th, sol A is on, sol B is off.

Not trying to get into a pissing match Lionel, just tying to clarify things a bit. I've been in the transmission sector for about 20 years, currently building a trans controller for the 4L60E, L80e, Ford AODE, E4OD, etc. I know quite well how they work. :)

Buddrow

[lionelhutz]

You're confusing the failure modes of solenoid A (fail to open vs not closing or leaking) with the failure modes of solenoid B.

If the A solenoid fails (electrical or mechanical) then you either get a 1-1-4-4 or 2-2-3-3 shift pattern depending on the failure being the solenoid failed open or failed closed.

If the B solenoid fails (electrical or mechanical) then you either get a 1-2-2-1 or 4-3-3-4 shift pattern depending on the failure being the solenoid failed open or failed closed.

If the solenoid B doesn't open (no electrical command to it) then the transmission won't select 1st or 2nd gear, with the shifter in OD (or highest gear selected).

I can read the service info directly from GM and follow the shift solenoid logic quite well. The failure of solenoid B to open (the PCM not commanding the solenoid) will not cause the transmission to only give gears 1 & 4.

The above all assumes the PCM thinks the solenoids are OK and tries to normally shift the transmission. Typically, the PCM will have circuits to detect that the shift solenoids are open circuit or don't have power applied to them.

Still, my point was that when you have the transmission in OD (or highest gear selected) it won't properly upshift through the 4 gears if the 2 main shift solenoids are not being controlled properly.

There is a 3-2 solenoid. If you're concerned about electrical issues only when downshifting to 2nd gear then that would be the place to focus. As I understand it, this solenoid modifies the 3-4 clutch release to 2-4 band apply timing. It seems to be for PCM commanded downshifts and not manual downshifts.

The info I have says that all manual downshifts except the 2-1 are initially hydraulic and then the PCM plays catch-up with the shift solenoids.

The 2 shift solenoids are often labelled as 1-2 and 2-3. The 1-2 is the same as A and the 2-3 is the same as B.