The 5 Transmission p codes

[drivewayguy]

I seen the video on this subject from GMTnation, I cannot find anything on it here to help me I am new to the site.

I have the five P0740 p0753 p0758 p0785 p1860.

I tested fuse 47 it has power both sides.

I swapped an ignition switch from my 02 envoy that I had smashed up. Reset codes and still got no power from vehicle.

I short test drive around the block and all 5 codes where back.

In the video it said to come here for the best help.

That's exactly what I am looking for. You help.

If there is a topic open on here already, please direct me to it. Vehicle is an 04 trailblazer LS 4x4.

Thank You all.

Don

 

[MAY03LT]

So yeah fuse 47 is the key on power feed to the trans solenoids. The pcm grounds the solenoids as needed.

If you got power on both sides of 47 with the key on, next thing I do is to go to the connector at the transmission. It is #10 in the second pic. It is hard to get to. With the key on, the pink wire in that connector should have good voltage. It might help to wiggle the harness 6-8" back from the connector and see if your voltage fluctuates.

In the first diagram you can see (if diagrams are your thing) that the circuit runs from the rear fuse box, up through the firewall, to the front fuse box, and back to the transmission (makes perfect sense). If no power is found at the pink wire and the wiggle test got no results, next would be the wiring at the front fuse box. But let's see the results of the trans connector first.

 

[djthumper]

Do you have power up to the front fuse box?

EDIT: Nevermind... May)3LT beat me to it.

 

[drivewayguy]

Thank You for the info.

You are not kidding. I crawled around under my Trailblazer for about 30 minutes. I could not find the connector. I thought I read it was on passenger side of the transmission. I only se some wires going down the driver side. All I could see was one rectangular looking connector. I am looking for the round one though correct?

I just had my blazer up on standard ramps in the front. Maybe I need to get it up hire.

Thanks again,

Don

 

[AtlWrk]

It is on the passenger side of the transmission but it's hidden above the oil pan towards the rear, pointing up. Do a Google image search of "4l60E" and you'll see the grey circular connector (a few pics even specifically point out the connector).

 

[drivewayguy]

this may seem stupid question. I have never test electrical back in there. would the tranny itself be a good known ground? it is tight in there for my hands, I may be able to get it off, but it does not look like I can pull it down much if any to be able to see any wires. What pin would the pink wire be? is there anywhere else I can test that wire? I have always enjoyed working on vehicles, but this tranny stuff could be so many things. Wow.

I may have to admit defeat and take it to the garage. As a guy who loves learning to fix things.

Thanks Again

Don

 

[drivewayguy]

Alright, took off the little heat shield and got to the connector. Tested the pink wire, actually tested them all and only one give some voltage. Started at 4V wiggle wiggle 12.3V wiggle wiggle 6V. There is no doubt fluctuation in the voltage on the wiggle test.

Oh man thanks for the help so far. Where do we go from here? Harness?

 

[drivewayguy]

Can anybody help me to what I can try from here.

Ignitions switch did not fix it, Power both sides fuse 47 key, Got to the Trans connector and tried the wiggle test. There is fluctuating voltage there, every time I moved the harness at all it gave me a different reading. I need to get this truck back on the road.

Please help if you can.

Thanks

Don

 

[Sparky]

Did you test the connector disconnected from the trans or was it still plugged in?

Try pulling the battery and spraying all contacts with good contact cleaner. If it is still sketchy you may need to replace the harness there.

 

[drivewayguy]

UPDATE!!!!!

Hey guys i have been out of town at work for a while. Back to try and see what is wrong with my truck.

I was wrong in my last post

I purchased a better multi meter, mine was an old cheap one. I checked again the pin E on the trans connector and i am getting between 11.5 and 12.2 volts there now.

Now i do not know what the heck to try.

I had taken to a garage also and they said they cannot find out what's wrong either.

I cannot afford to just take it to a different shop until someone finds out whats wrong.

If any one can lead to try other things. I am open to suggestions.

Thanks

 

[Texan]

What is the mileage on the transmission?
Has the transmission oil and filter been changed?
Can you drive it? How does it shift? We need more information.

 

[drivewayguy]

230000 kilometers, now sure on the filter change. Just recently got this trailblazer. Tranny fluid has great color and no burnt smell. yes I can drive it. It is in limp mode in third gear. Does not shift, very low power especially on take off or on hills. Just to get it on ramps I had to give it a lot of gas. If I put it in reverse and punch it. it has a ton of power, fuse 47 good, changed out an ignition switch out of an envoy I have here that I smashed up. checked the pin E at trans connector. voltage between 11.5 and 12.2. 2004 trailblazer 4.2l.

 

[drivewayguy]

Please folks, I know there is a ton of knowledge out there and I could really sue some if it.

Thank You

 

[Texan]

When it is in "limp mode", is the REP (reduced engine power) light
on at the instrument cluster?

 

[drivewayguy]

No REP light.


should there be voltage on any other pins on the trans connector?

 

[Sparky]

Wish I could help more but I'm out of ideas...

 

[Mounce]

I thought limp mode is REP mode. Has your tranny possibly just messed up so it decided to spew codes?

 

[drivewayguy]

I have no idea, it was running fine, went and got coffee one morning, went back out a couple hours later and it had no power, scanned it with obdii, got the five codes and you see everything else I have tried, Thanks guys guy, even to it to a garage and they could not help me either. Frustrating.

Is there I way to tell if the tranny itself is poached|?

Is there a chance there could be a short in the internal wire harness?

 

[Mooseman]

I have a feeling it's a wiring issue inside the transmission, possibly to those solenoids. Could be a particular connector inside that connects to those solenoids (on the left of the wiring schematic) otherwise you might also get codes for the other sensors (on the right). I doubt your tranny is pooched because it wouldn't throw 5 codes all at the same time. It's obviously a wiring issue. My bet would be the connection of the red wire inside to the pink wire outside is broken since you're getting 12V at the pink wire/pin E. To check that red wire, you'll have to drop the pan. you'll be able to check for 12V power in the ACC or RUN position without having to start the engine.

 

[drivewayguy]

Thanks again,

Maybe someone could help with this question? The P0785 Shift/timing solenoid. I can not see that solenoid in any of the transmission diagrams I look at. Is the shift control solenoid the same thing?

Also can some one direct me to link to be able to test following for both power and Ohms, 1-2, 3-4 shift solenoids, TCC, shift timing solenoid or what ever the p0785 code is and the tcc/pwm?

I am very grateful for all your help folk's really thank you so much, great site I will recommend it to all my DYI friends.

 

[Mooseman]

I don't know what the ohms should be but they shouldn't be open. Come to think of it, you should be able to test at the connector for that.

 

[Sparky]

Most solenoids ohm out at almost no resistance. As Moose said if they test open then they are definitely bad, and if you have one that ohms out significantly higher than the others I'd suspect it of being bad as well.

Moose also has the service manuals linked in his sig, might be the info you're looking for there.

 

[drivewayguy]

Awsome!!!

Thanks, that manual will most certainly come in handy, I will check the red wire from the pink wire inside and go from there. Another thing I just noticed today is. I do have second gear if I go to it manually.

Will that manual tell me how to test solenoids for opens at the connector. External connector or internal?

Thank Again,

 

[Texan]

I would suggest that you goggle 4L60E and look for information
and instructions about this transmission.

 

[Mooseman]

Found this in GM-SI:

TCC Solenoid: Between terminals T and E, should be between 21-33 ohms. Between terminal T and ground or E and ground should be greater than 250K ohms.

1-2 shift solenoid: Between terminals A and E should be between 19-33 ohms. Between terminal A and ground or E and ground should be greater than 250K ohms.

2-3 shift solenoid: Between terminals B and E should be between 19-33 ohms. Between terminal B and ground or E and ground should be greater than 250K ohms.

3-2 downshift solenoid: Between terminals S and E should be between 20-32 ohms. Between terminal S and ground or E and ground should be greater than 250K ohms.

TCC solenoid: Between terminals U and E should be between 10-15 ohms. Between terminal U and ground or E and ground should be greater than 250K ohms.

 

[drivewayguy]

Texan, I have read and done a ton of research on this, I mean a lot, really .I have googled my fingers. I could not find much on what else to try after testing fuse and connectors. I also took it to a garage in Sudbury Ontario.
he told me he has never seen this before and could not help. I would not be on here looking for help if I could find the information I am looking for. I take a lot of pride in researching and learning to fix thing over the years. The electrical stuff I am getting better at, but still learning, researching and reading.

Mooseman,

Thank You very much that is going to come in handy.

Only 1 more question. May sound stupid, like I say I am fairly new at figuring out more about electrical beyond just a test light. Is it the external connector I am testing or am I dropping the pan and testing inside. I have never heard the term before to test for opens.

Thank You All once again.

 

[Sparky]

It says terminals so I am assuming that is at the plug.

Testing for opens is just that, looking for open circuits. If you are supposed to get a resistance value (20 ohms for example) but you get infinity ohms then that is an open circuit.

 

[Mooseman]

You can test at the connector before dropping the pan and you'll need an actual digital multimeter rather than a test light.

 

[drivewayguy]

Thanks again,

Both off you great information, and I just purchased a new digital multimeter.

 

[Texan]

I have never had a problem with my transmission (knock on wood).
I do not know the answer to your question about P0785 in post #20.
I would suggest dropping the pan to ohm the solenoid coils. You
can disconnect the wires (terminals) at each solenoid and measure
the ohms of the coil with your DMM. This would be the time to change
the filter and add new transmission fluid. Just a suggestion.

 

[Mooseman]

I'm still putting money on the 12V+ red wire that feeds all those solenoids, whether at the connector or inside the tranny.

 

[drivewayguy]

Finally got around to testing the harness leading into the transmission. From Pin e to any other pin or ground I got absolutely nothing. The DMM was at 1 for all tests, key on and off.
Funny though today when I went to put it up on the ramps, I blew a tranny line, think this is related maybe.

Looks like I am going into the pan.

 

[Sparky]

Ouch. Good luck man. I'm curious what you'll find in there.

I'm assuming you had it on ohms mode not voltage testing mode right?

 

[drivewayguy]

Yes it was on ohms, tested it on a coil pack I have here, worked fine. Blowing a line did not make my day. Been without a truck for a month now, it is pickerel season 2 weeks ago and still have not been able to tow my boat to go fishing. Arrrrg!

I will make sure to post anything I find, especially a solution.

 

[drivewayguy]

Ok thanks everyone who helped me. Problem found but not solved. Got the pan off and the tranny fluid was like mud, and full of all kinds of metal parts and shaving, as it turns out,

I am going to look for a used tranny, can anyone tell me if all 4L60E transmissions are the same. Or what years and vehicles I may be able to find one from. My trailblazer is an 04 LS 4x4.

Thanks again to everyone.

 

[coolasice]

Need one from a 4x4 trailblazer or envoy with 4.2 as the bellhousing is unique

 

[Sparky]

^ What he said ^

 

[Mooseman]

If you look up transnational on car-part.com, it should give you a good idea of which years will work. Off hand, I think anything from 2002 to 2005 for an I6 4x4 will work.

 

[Sparky]

Did the transmissions change at all from 2006-2009?

 

[Mooseman]

Possible. I know the shift kits for these only go to 2006. Car-part.com only lists 2004 as compatible for 2004, 2002 and 2003 as compatible to each other, 2005 to 2007 as compatible, 2008 by itself with two different transmission models, and 2009 by itself.