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Grant34
Novice
Dec 23, 2012, 12:53 PM
Post #1 of 12
(2552 views)
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4l65hd trans code read bad shift soloniods I replaced both solonoids but still reading shift solonoid b trans shifts smoothly in 1 &2nd no 3 4 and kickdown is smooth could it be pcs or valve body or ?? Please help thx
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nickwarner
Veteran
/ Moderator
Dec 23, 2012, 2:07 PM
Post #2 of 12
(2530 views)
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what vehicle is this in? Which engine? What is the exact code number coming up?
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Grant34
Novice
Dec 23, 2012, 2:33 PM
Post #3 of 12
(2523 views)
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1998 Pontiac grand prix 3800v6 supercharged code 303099 cleared then po756 returned
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nickwarner
Veteran
/ Moderator
Dec 23, 2012, 4:59 PM
Post #4 of 12
(2506 views)
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303099? There's no such code my man. By the way, this is a 4T65E trans. The T stands for transverse mounting, L is longitudinal mounting like a RWD uses. Got some info on that code for you below. How many miles are on this?
P0756 - Shift Solenoid B Performance or Stuck Off
Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty shift solenoid B valve
- Shift solenoid B valve harness or connectors
- Shift solenoid B valve circuit is open or shorted
Help with this
Tech notes
When the a transmission solenoid is stuck off, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is very dirty, it is recommend changing the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a transmission mechanical failure and that the transmission will need to be rebuilt or replaced.
Help with this
When is the code detected?
The P0756 code is detected when the ECM has detected a mechanical fault with the solenoid energized, valve stuck off
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission will not shift gears.
P0756 Description
Shift solenoid valve B is turned ON or OFF by the Transmission Control Module (TCM) in response to signals sent from the park/neutral position (PNP) switch, vehicle speed and Engine Control Module (ECM) (throttle opening). Gears will then be shifted to the optimum position.
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Grant34
Novice
Dec 23, 2012, 5:27 PM
Post #5 of 12
(2494 views)
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Ok oops on the 4l I meant 4t and according to autozone there is three trans which also has three different shift solonoids there's a 4t60e, 4t65e, and 4t65hd trans hd stands for heavy duty which they list solonoids for all three and there all different. And the one code was just from a dealership code.. So there is a trans control module? Do u know we're it is located on this vehicle? Mileage is 130,000 I just don't think it needs rebuilt or changed everything else shifts way to good what would be ur best opinion
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nickwarner
Veteran
/ Moderator
Dec 23, 2012, 5:46 PM
Post #6 of 12
(2491 views)
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Tranmission control and engine control are integrated into the PCM as one unit. 130,000 miles is more than enough to need a rebuild. If you have never changed the fluid, its quite likely this is why you're getting the code. It wouldn't take much clutch lining debris to plug the filter screen of the valvebody and set this code. The PCM on these newer vehicles is quite good at compensating for issues over time. You'd be amazed at how bad parts can get before the driver notices any issues. I'd be looking at this closely. Sometimes the code will set simply from a wiring harness issue. There are electrical checks that will need to be made to find out if that is the case. But I wouldn't leave this be just because you aren't noticing driveability issues right now. If the diagnosis is outside of what you feel comfortable with, it may be worthwhile to swing into a transmission shop and pay them for a diagnosis.
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Grant34
Novice
Dec 23, 2012, 6:03 PM
Post #7 of 12
(2483 views)
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Ya that's the thing I bought the a month ago the trans fluid was bad I mean bad but there was no metal shavens or anything which was surprising and I've changed the fluid and screen naturally when I changed both shift solonoids was told the pressure control solonoid could cause it or the valve body I'm just trying to get more opinions to decide to ter it back apart or put another trans in it
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nickwarner
Veteran
/ Moderator
Dec 23, 2012, 6:23 PM
Post #8 of 12
(2480 views)
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I'm talking about a small screen inside the valvebody of the transmission. Not the one you changed when you dropped the pan. The passages of that are very small and hard to get cleaned once fouled up without diassembly. Remember that fluid doesn't just get itself dirty. It gets dark as it gets contaminated by clutch lining material. So something heavily loaded with clutch lining doesn't get better by changing the neglected fluid if its gone too far. That material isn't coming back to those discs.
One of our regulars, Marine Grunt just wrapped up a full rebuild of this trans in his minivan. He may have a few pics of that valvebody he could post for you when he comes across this thread.
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Grant34
Novice
Dec 24, 2012, 8:43 AM
Post #9 of 12
(2461 views)
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Oh ok thought u were talking about the big screen, ya that would be great if I could get some pics of that, cause after Xmas here I'm gonna ter it all back apart, that pressure control solonoid in there u think I should change that since I'm there? And I thank you and merry christmas
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nickwarner
Veteran
/ Moderator
Dec 24, 2012, 9:15 AM
Post #10 of 12
(2460 views)
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I would change the EPC solenoid too. They were known for failures. If you're going to get this deep into the your trans it might be a good idea to get an ATSG manual and the update book to be certain everything is done properly.
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MarineGrunt
Enthusiast
Jan 5, 2013, 12:07 PM
Post #11 of 12
(2406 views)
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I took a BUNCH of pictures during my rebuild. Let me know what pictures you want and I can post them. I ended up having to rebuild ours because the tranny completely went. A week or so prior I lost overdrive. When I tore it apart I found all kinds of damaged parts. When one thing goes it tends to affect about everything else. I'm not saying yours has any internal damage, but if the fluid was as bad as you said, who knows what could be going on inside.
Here's a link to my rebuild. There are a lot of posts. This was my first and only tranny rebuild so I had a lot of questions. I eventually plan on doing a "final wrap up" on the rebuild but haven't had the time.
http://autoforums.carjunky.com/...nny_Removal_P127528/
I'm no pro when it comes to trannies, but if I can be of any help, just let me know. One thing I know I can do is get you pretty much any picture you want to look at.
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nickwarner
Veteran
/ Moderator
Jan 5, 2013, 3:21 PM
Post #12 of 12
(2399 views)
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He's not exaggerating details on how many pics he too either.That thread set a new site record here as the longest one we've ever had.
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