Hard shifting, codes PO133, PO781, and P1336

Good afternoon,

I attached the flow chart for the 781 code. There are several possibilities and one of them has to do with the crank sensor. It looks like it was replaced but never relearned. This must be done to make sure the correct signal is being sent to the module.

https://www.2carpros.com/articles/automatic-transmission-problems

I also attached a wiring diagram of the transmission for you as well.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Roy

Thank you so much for the help, it means a lot.

Also I am going to have the dealer check it out and see what's going on. When I installed the PCM, I brought the car over to the dealer to get it flashed and after he was done, I got the blinking wrench right after. Do you think that since the PCMs are set to Crankshaft Relearn Procedure "No" when they are brand new; he tried to do the relearn procedure but failed at doing so? I was reading the diagrams attached and saw that if there are any misfires, the CKP procedure will not work. I haven't replaced the CKP sensor yet and wondered if this would cause any misfires due to it giving information to the PCM.

I tested the solenoids with voltage but I am going to see if I can get them audibly tested as well. The thing is is this is my second valve body from the same seller and there is no change at all. If you all want I can post the original codes from my stock valve body, and the codes from the 2 valve bodies I bought.

Now that I remember I did notice that when I put the valve bodies in, the car would begin to shift normally after a few hard shifts but then degraded back to the usual hard shifts again. Does this seem like an electrical issue, I even tested the voltage on the valve body that I bought and the solenoids looked good

I'm just a college student trying to get by and I am very grateful for your responses.

I appreciate the help.

Okay, that relearn has to be done. As long as there is no code for the crank sensor, it should run the relearn. If it does not, then you may have a bad ECM. Was the replacement new or used?

Roy

I bought the new one from Summit Racing, it's the one located behind the car battery on the firewall.

It still could be bad if it will not do the relearn procedure.

Is the check engine light on?

Roy

Yes it's still on.

Does it have a 335 code? If it does, it will not perform the relearn.

Roy

You think the dealership doesn't know how to flash it? Does the misfires during the relearn procedure come from the PCM?

It has the PO781 and P1336.

As well as the PO133 Oxygen sensor error.

Okay, it should run.

What did the dealer tell you about it not working?

Roy

I'm going to go Monday morning again and talk with the head technician because the last guy messed it up I think because he said he put in my VIN number and now it all lines up with the system. But I am going Monday for round 2 it only goes 35 MPH ow without doing a huge clunk. So I go slow on the road.

Maybe he does not know how to do the crankshaft relearn procedure and that's what caused all of this mishap. Do you think so? Thank you, you are really helping me out with this.

The scan tool is what tells you what to do for the relearn. It is hard to get the procedure wrong.

Roy

I agree with you, just trying to understand why I keep getting the code. Do you think the downstream exhaust heated O2 sensor will cause the PCM to have wrong codes and shift wrong? Because I also have the PO133 Oxygen sensor code as well.

Before the 781 will go away, the crank relearn has to be done. It is part of the flow chart for the 781 code.

Roy

Oh, I see so basically the 781 1-2 shift error is caused from the failed crankshaft relearn procedure, are there other people besides the dealer that can perform this crank relearn. And what system would be used so I can ask around? And if it fails again there's something causing a misfire.

No, it contributes to the hard shifts. You need that finished first so the ECM sees the correct signal for the shifting.

Roy

So should I take it and have the relearn procedure done again or should I still figure out what's causing the 781 code? Thanks. Sorry I am completely new to all of this. What would you do in my situation?

You need to have the relearn done and verified it is complete before proceeding on the 781. It is possible it will help it substantially.

Roy

Thanks, I will head on out and get the relearn procedure going. Do you have a recommended tool that I could look out for? Can I have a non-dealership shop do it?

Any shop with an advanced scan tool can perform this procedure. It takes about 30 minutes.

Roy

So I took it to a shop and the car wouldn't pass the crankshaft relearn procedure. Said there could be internal pressure, transmission pump problems, clutch pack issues, electrical, or even the solenoids might be stuck because we got another "Solenoid B stuck on or off" error code. He was a cool guy, doesn't deal with transmissions. Don't know where to go from here. I'll go to the dealer Monday and will keep you posted.

It still needs the relearn completed before you do anything.

What was the new code?

Roy

The guy said it was the error code associated with Solenoid B being stuck on or off and during the process they said it wasn't giving any misfires but then said it was registering as a misfire and the crankshaft relearn failed. I took a picture of the codes and the message the scanner gave.

It was a Snap on Titan and gave a PO756 and PO789 error codes and the guy said it did the relearn. The message on the scanner during the process said: "Crankshaft Position variation not will not learn this ignition cycle because the Total Misfire Failures test did not pass. Turn engine off, exit test and try again."

Thanks

Okay, did it complete the relearn? You said it did and then you said it did not. I am confused.

I attached the flow chart for both codes. This looks to be electrical. You will need an advanced scan tool to monitor the action of the solenoids when commanded open and closed.

Roy

Sorry I may have worded things wrong, I've been out in the heat all day. When I went in, it took three different mechanics to try to get the crankshaft relearn going, during the first two attempts is when they got the message of it failing.

The last guy working on it said it gave those two error codes and that it did complete the relearn procedure but then discussed the potential causes of the hard shifting. I personally don't know if it learned or not, I might have to plug it into another OBD to see if that DTC shows up again.

I appreciate the diagrams, I am starting to think it is an electrical issue.

You are welcome.

Always glad to help.

Roy

Just to keep you updated, I got the car scanned again with a OBD II Innova 5300LaT and the PO756 and PO789 error codes disappeared while the PO781 and P1336 came back again with the PO133 gone. The car only does the reverse slam once it heats up and doesn't hard shift in third gear. So weird.

Anyways, just letting you know what's going on so this thread could possibly help someone else out in the same situation.

Okay, they will be back. When you clear the codes, all that does is make the ECM forget the codes. Without repairs, they will be back.

1336 is the key once again with the crank relearn. I attached the flow chart for 1336.

Roy

Yeah, you are right that's why I'm going to take it to the dealership tomorrow, they have all the software these shops don't have. Everyone is saying you are right and I'm going to have them perform the crankshaft relearn. And they don't have the machinery GM has. I will keep you posted.

Sounds good.

Keep me updated.

Roy

So I took it to the dealer and they successfully passed the crankshaft relearn. You were right all along. The dealer went through the flowchart and determined the white wire B4 is the one that is causing an open circuit short to the solenoid. He even had the same diagram you gave me too! He circled on the diagram where to replace it on the transmission wiring harness.

Nice. Glad to hear it.

Once you replace that, hopefully, everything will return to normal.

Roy

Hello, I had a few questions, means a lot. So I asked around and the auto shops are too busy or are too scared to work on the car lol. I am debating if I should do it on my own here. On the white B4 transaxle wire, it runs from the wiring harness on the valve body all the way underneath the fuse box?

I also saw on the diagram you gave me and saw that it had a .5 on it which has led me to determine that it is 20 gage wire, hope I'm right. I am planning on cutting the wire from the harness and at the end of the fuse box and then crimping some automotive wire from a hardware store to it (or from a pick apart) and putting the heat gun on it. I found this out from an old GM guide and am hoping I can do this. Is there a way to find the exact wire from the end of the fuse box? It looks a bit tricky since it connects to the fuse box as Circuit 1523.

Much appreciated.

It is an 18 gauge wire. Not a 20. You need to solder and shrink wrap for the repair.

Roy

So, I had an auto shop repair the wire and the check engine light came back on and there was no improvement. Had the codes cleared by the dealer too when I had it do the relearn procedure. Just keeping you updated.

Okay, did anyone verify power through that wire to confirm the repair?

Roy