0751 code

[lint]

I have the code 0751 on 2004 trailblazer 159000 miles on always had good fluid and changed does not smell . lost first gear and 4th or over drive sometimes goes in 4th till stepping on the pedal then back to 3rd . It didn't slip when this first started just tries to find different gears checked all fuses all good next step to buy shift solenoid 1.2. haven't taken pan off yet to see if and metals in it. says there are two solenoids 1-2 and 2-3 but cant find the difference on rock auto, Are both solenoids the same I know there are two beside each other in the tranny I am going to replace both does anyone know the part numbers or if they are the same or if something else may be wrong , any help would be appreciated thanks

 

[Mooseman]

Try looking up an online microfiche, like GMPartsdirect, and check the part numbers if they are the same. I'd use an ACDelco or GM part from the dealer.

 

[Reprise]

Those solenoids are actually considered interchangeable - you can swap them, if you suspect only one is blown - and see if the problem follows the swap (the one controls 1-2, while the other controls 2-3).

If it shifts the issue (no pun intended) to the other side - then you've found the fix, and for cheap. If it doesn't - then you don't have to worry about dropping the pan again and swapping them back.

Just be careful when you remove the harness clips from them. If the release clip has the ends facing down toward you - not to worry. Just use a pick tool to swing them around 180", so that the 'flat' end on the top faces you; you can then use the pick to unseat them from the solenoid body, and finish taking them out w/ your fingers. IIRC, you can take them out with the valve body in the case. If not, you can loosen the bolts enough in the VB enough to drop it down enough to remove the solenoids.

Try not to take the bolts out completely - and if you do - note exactly where they go, as they are 4 different lengths - put a 'long' bolt in a 'short' hole, and you'll lock up the trans (rebuild time). Tightening sequence is CCW, from center outward, in a spiral pattern. Use a torque wrench to tighten to 9-10 ft. lbs in 2-3 passes.

When you get the solenoids out, give them a good spray with brake cleaner, especially in the screen area. If you have compressed air, see if you can feel the air flowing through on the other side. Also, there are 2 (?) O-rings that seat the solenoid to the VB, and prevent leakage of fluid past their seats - if any of those are worn / bad / missing, just get a new solenoid to replace it - they're not really expensive, and they're readily available (GM built a lot of 4L60's over the years). They should seat in the VB with a little resistance, and take a little bit of effort to remove.

Being a 2004, you may or may not have a separate TCM; if you do, it'll be on the passenger side of the case. Carefully pull the harness from it for 30min or so, so that when you prepare to drive the truck again, it's in a relearning mode. Or, disconnect the battery (but be aware that the PCM will also lose its memory and go into relearning mode as well).

 

[Mooseman]

Those solenoids are actually considered interchangeable - you can swap them, if you suspect only one is blown - and see if the problem follows the swap (the one controls 1-2, while the other controls 2-3).

Although they are interchangeable, I'd just replace both of them to avoid having to drop the pan again. If one of them is dead, might as well replace both and be done.

 

[Reprise]

Although they are interchangeable, I'd just replace both of them to avoid having to drop the pan again. If one of them is dead, might as well replace both and be done.

I'd probably do the same, especially since the code reported relates directly to the 1-2 solenoid. But if the OP wanted to test before shelling out the money for the parts, he could. If that made no difference, I don't think I'd drop the pan a second time w/o having a good idea of the 'real' issue.

 

[lint]

Thanks Moosman and Reprise I needed good advice . When taking the pan down in the driveway on ramps with no drain plug you like to be a little more confident that your going in a good direction '' less work'' This will be the 4th time taking the pan down in 5 years '' should have got a pan with a drain plug'' I found the solenoids on Rockauto for 10.31 I think the first Acdelco ones are good . http://www.rockauto.com/en/catalog/...,transmission-automatic,control+solenoid,8476

 

[Mooseman]

To avoid the mess, you can pump out the fluid by disconnecting the cooler line, putting a hose on it and put the other end in a bucket then start the engine. Let it run until it starts to sputter and shut off the engine. Check for May03LT's video on YouTube on doing a tranny flush:

 

[lint]

lol Already have the hose and bucket, its no fun lying in transmission fluid ,been there to many times ,I should have wised up long before I did Thanks Mooseman