P0751 and 1-2 Neutral Symptom

[LSBoostedModular]

Need some help please. I’m going to tackle the valve body my self. Having issues when in D leaving from a stop light it will act like it’s in neutral and rev out, then eventually will pop in gear. Only code I get sometimes is p0751. I took to a transmission shop and they put in a shift kit. Did a relearn. Said it was fixed, It’s not! It’s a very intermittent issue but it still does happen and it’s annoying! So I’m ordering a trans go tcc and clutch select valve kit, new .250 check balls and o ring plugs. Im going to do this my self as I can turn wrenches but have never went inside a 6l80e or any transmission. So my questions are.

Do I use the 7 check balls or do I use 8? Looks like they added the 8th on later.

Sonnax zip kit or just the cs/tcc kit. I won’t be putting pressure regulator in pump housing because I don’t want to go that far in. Just want to drop valve body.

Do I get a separator plate or reuse my old one, I’ve read it’s good to replace because the gasket is molded on. Not a problem but there is updated ones available. I have a 2007 Denali 6.2 awd. And I believe version 2 is used with a transgo kit. So I’m getting the valve body kit does anyone know which part number plate I use with the transgo/sonnax valve body parts.

Do I have to replace techum and/or seals when splitting the case. Do I have to replace the wiring harness as well. So confusing on what’s required to replace when just taking out the valve body. Also ordered a autel mx808s to do the transmission adapt learn. Also got the torx plus socket coming! Any info would be greatly appreciated or if there’s someone on here that sells everything needed to upgrade valve body parts. Thank you in advance.

Jason

 

[Joseph Garcia]

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

 

[LSBoostedModular]

Thank you, appreciate it. I just want to do it right the first time! If I need to replace other parts I’m not upgrading I will.

Right now from the info I can gather from the search I believe it’s the plate part number I listed with cs/tcg kit. End cap plugs with orings, new check balls, new seals for the tehcm, trans boost valve, tranny pan gasket and filter. Tool wise I ordered the autel scanner to do relearn and torx plug socket.

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.

 

[swathdiver]

Check out what one of our members did as preventive maintenance:

6L80 Sonnax ZIP Kit, Pressure Switch rebuild, remote filter install, and fluid flush in 2013 Escalade ESV (Pic heavy)

Hello Gentlemen, Over the past few days, I have completed the following work to the 6L80 transmission in my 2013 Escalade ESV: -rebuilt the TECHM pressure switches using Sonnax parts -installed most of the Sonnax ZIP kit in the valve body -replaced the filter -installed a new pan with a drain...

www.tahoeyukonforum.com

Nick will be along when he comes back online. @NickTransmissions

 

[NickTransmissions]

Need some help please. I’m going to tackle the valve body my self. Having issues when in D leaving from a stop light it will act like it’s in neutral and rev out, then eventually will pop in gear. Only code I get sometimes is p0751. I took to a transmission shop and they put in a shift kit. Did a relearn. Said it was fixed, It’s not! It’s a very intermittent issue but it still does happen and it’s annoying! So I’m ordering a trans go tcc and clutch select valve kit, new .250 check balls and o ring plugs. Im going to do this my self as I can turn wrenches but have never went inside a 6l80e or any transmission. So my questions are.

Do I use the 7 check balls or do I use 8? Looks like they added the 8th on later.

Sonnax zip kit or just the cs/tcc kit. I won’t be putting pressure regulator in pump housing because I don’t want to go that far in. Just want to drop valve body.

Do I get a separator plate or reuse my old one, I’ve read it’s good to replace because the gasket is molded on. Not a problem but there is updated ones available. I have a 2007 Denali 6.2 awd. And I believe version 2 is used with a transgo kit. So I’m getting the valve body kit does anyone know which part number plate I use with the transgo/sonnax valve body parts.

Do I have to replace techum and/or seals when splitting the case. Do I have to replace the wiring harness as well. So confusing on what’s required to replace when just taking out the valve body. Also ordered a autel mx808s to do the transmission adapt learn. Also got the torx plus socket coming! Any info would be greatly appreciated or if there’s someone on here that sells everything needed to upgrade valve body parts. Thank you in advance.

Jason

Go to your local GM dealership's parts department, give the counter guy the last eight digits of your VIN and he will sell you the correct parts you need. You will use 7 check balls as you have a gen1 spacer plate...a 2nd design plate was introduced in 2010 and third design with the 8th check ball was put into production for the 2014 model year. For anyone else reading, you can retro the 3rd design plate to all valve bodies in 2010-2013 as long as you install the 8th check ball in those valve bodies.

My video covers spacer plate differences and how to ID a given plate:

P0751 can also be triggered by a clogged or cracked filter, leaking clutch select valve bore plugs (lower valve body), sticking 4-5-6 clutch boost or regulator valve (upper valve body) or worn/shrinking check balls (valve body)

 

[LSBoostedModular]

Go to your local GM dealership's parts department, give the counter guy the last eight digits of your VIN and he will sell you the correct parts you need. You will use 7 check balls as you have a gen1 spacer plate...a 2nd design plate was introduced in 2010 and third design with the 8th check ball was put into production for the 2014 model year. For anyone else reading, you can retro the 3rd design plate to all valve bodies in 2010-2013 as long as you install the 8th check ball in those valve bodies.

My video covers spacer plate differences and how to ID a given plate:

P0751 can also be triggered by a clogged or cracked filter, leaking clutch select valve bore plugs (lower valve body), sticking 4-5-6 clutch boost or regulator valve (upper valve body) or worn/shrinking check balls (valve body)

Appreciate your reply nick! I Watched video, thank you. I will have to pull mine out first I believe because before I bought the truck previous owner replaced transmission. I def don’t want to order wrong parts. I will pull mine and count the notches and replace with the same version. Yukon is a 2007.So with that code and symptoms I should replace all parts you mentioned, which I will. Couple questions. I found the 4-5-6 regulator valve sonnax part #104740-50
I can’t find the 4-5-6 boost valve anywhere. Is there a kit with them? Also I got the sonnax .250 check balls (10) but I’m only using 7 correct? Got the o ring end plug kit from sonnax. Also got the cs/tcc kit part #6L8 CS-TCC. And compensator feed regulator boost valve part # 6L80-CFR. I will also replace with new tranny filter like you mentioned might be an issue. Besides the parts you mentioned you recommend anything else in valve bodies to be replaced or a kit while I’m in there? Is there a 1-2-3 regulator valve I should replace since I’m doing the 4-5-6? Also when doing all this I can reuse the tehcm and speed sensor etc harness correct? I just need to replace tehcm diaphragms and separator plate then I can slap it all back together tq @ 71inch lbs, a new filter and pan gasket? Then complete a relearn with autel or am I missing anything? Sorry for the questions, just getting mixed answers all over the place so figure I come here and ask the people that have done it and know. I appreciate all the info and advice!

 

[NickTransmissions]

Appreciate your reply nick! I Watched video, thank you. I will have to pull mine out first I believe because before I bought the truck previous owner replaced transmission. I def don’t want to order wrong parts. I will pull mine and count the notches and replace with the same version. Yukon is a 2007.So with that code and symptoms I should replace all parts you mentioned, which I will. Couple questions. I found the 4-5-6 regulator valve sonnax part #104740-50
I can’t find the 4-5-6 boost valve anywhere. Is there a kit with them? Also I got the sonnax .250 check balls (10) but I’m only using 7 correct? Got the o ring end plug kit from sonnax. Also got the cs/tcc kit part #6L8 CS-TCC. And compensator feed regulator boost valve part # 6L80-CFR. I will also replace with new tranny filter like you mentioned might be an issue. Besides the parts you mentioned you recommend anything else in valve bodies to be replaced or a kit while I’m in there? Is there a 1-2-3 regulator valve I should replace since I’m doing the 4-5-6? Also when doing all this I can reuse the tehcm and speed sensor etc harness correct? I just need to replace tehcm diaphragms and separator plate then I can slap it all back together tq @ 71inch lbs, a new filter and pan gasket? Then complete a relearn with autel or am I missing anything? Sorry for the questions, just getting mixed answers all over the place so figure I come here and ask the people that have done it and know. I appreciate all the info and advice!

Just buy the Sonnax Zip kit for the 6L80/90 - it will have everything you would want to install into the valve body...There will be a couple parts for the pump but you won't be able to install those unless you pull the trans, remove and partially disassemble the pump.

If the vehicle is a 2007, it should have a 2007-2009 valve body assembly. Look at the year of the valve body, which is casted into the upper and lower valve body. Should see something '07'...

I would test your TEHCM since you have p0751; as mentioned it could be caused by the valve body but it could be a bad solenoid. If it's the latter, you're purchasing a new TEHCM.

 

[LSBoostedModular]

Just buy the Sonnax Zip kit for the 6L80/90 - it will have everything you would want to install into the valve body...There will be a couple parts for the pump but you won't be able to install those unless you pull the trans, remove and partially disassemble the pump.

If the vehicle is a 2007, it should have a 2007-2009 valve body assembly. Look at the year of the valve body, which is casted into the upper and lower valve body. Should see something '07'...

I would test your TEHCM since you have p0751; as mentioned it could be caused by the valve body but it could be a bad solenoid. If it's the latter, you're purchasing a new TEHCM.

Ok I will get the sonnax zip kit. I’m assuming that comes with the 456 regulator and boost valve. I read the parts list and it just says regulator but assuming that’s what you’re talking about! I’ll pull pan and body in the am and get back with you if you don’t mind. Appreciate your help so much! So to get it right. Install zip kit and check balls. And test tehcm. I’ll check some videos so I can test that correctly. Supposedly the mechanic last week swapped the tehcm, it didn’t fix the issue. So uninstalled and put a shift kit in instead and said it was fixed. But to be honest I just jacked it up so I can work on it in the am took a quick peek and doesn’t look like a socket got used on any of those bolts in years lol. So he took 700 from me just to give my truck back with the same symptoms ‍ Fun starts in the am. Can’t wait to take it apart and see what I find. Thank you nick. All info is very much appreciated

 

[LSBoostedModular]

 

[LSBoostedModular]

@NickTransmissions Looks like this check ball might be the culprit. When I split the case it was stuck in the separator plate. So I’m still going to change all of them with the sonnax ones, test tehcm and change diaphragms, install the zip kit minus the pump parts. Should I still get the transgo cs/tss kit to install as well and the cooler bypass valve. From a search the 456 comes with the zip kit so that’s good.

 

[LSBoostedModular]

Here’s the plate

 

[LSBoostedModular]

And these numbers on other half

 

[LSBoostedModular]

Not normal for a little material of some sort on body where tehcm was attached too?

 

[LSBoostedModular]

And this fell right out when I took valve body out of transmission

 

[LSBoostedModular]

Does anyone know if these marks are a reason for concern? I could definitely notice the discoloration but they are still smooth and round. Not sure what they’re wearing on.

 

[Fless]

Does anyone know if these marks are a reason for concern? I could definitely notice the discoloration but they are still smooth and round. Not sure what they’re wearing on.

Why not converse with @NickTransmissions about it?

 

[LSBoostedModular]

Why not converse with @NickTransmissions about it?

We have been chatting on here but I don’t have his personal number or email. I don’t want to bother him at all. He’s been a super help already! That’s why I posted all pics and questions on here. He’s probably super busy!

 

[LSBoostedModular]

So everything’s installed. Watched nicks video and followed every direction and put in a new ims and input output sensors. Torqued to spec in correct sequence. Filled her up with fluid and tried to do the adapt relearn with the autel and it doesn’t offer it for that vehicle! Do the 2007 Yukon require an adapt relearn? Tried an outdated snap on scanner and that wouldn’t work either. Should I hold throttle down for 15 sec to reset it all. Or take it to the dealer? Don’t want to drive it as everywhere I read said to do a adapt relearn

 

[LSBoostedModular]

@NickTransmissions does a 2007 Yukon require an adapt relearn? Ive tried a autel mx808s, older snap on scanner, and a launch431 and none of them offer an adapt relearn for that particular year/mode! Is mine too old? What do you recommend? Does a tech2 offer it for a 2007 or would a pedal reset/disconnect battery for 30 mins be the way for my old Yukon. I want to do it the right way so I haven’t drove it since I finished the install because I want to do it correctly but don’t have much action on this forum. Also appreciate your videos I came across on YouTube made the install super easy and straight forward. Thank you