ok unlike most My converter does not unlock most of the time. I have replaced and checked new  alt. with new method, replace control solenoids,  when I come to a stop it stays locked ,shifting to neutral does not unlock it. when I put back in gear will kill engine. when I restart it is unlocked. all though when I started it today after sitting all nite it was locked, shout it off when restarted it was unlocked.it seems to work fine when cold after warm up it fails to unlock. most of the time.also it was rebuilt about 10000 miles ago with new half billet converter.truck has 220000 miles

Guessing the converter is shot,  it should unlock as soon as trans pressure goes down if it is anything other than the converter.

 

sounds like the clutch is binding

Edited October 10, 20177 yr by Me78569

I was looking for a cheaper answer but was afraid of this have any suggestions for a replacement the engine is stock but  I do tow a 7000lb rv.

Dpc sells good quality good priced units

Be sure that the orange/black wire at pin #C2-11 on the PCM is not shorting to ground or the torque convertor clutch solenoid is hanging up.

. 

 

 

Possibly valve body?

I would strongly suggest checking line pressure but it does sound like the converter may be done. You do not have a lock up switch do you???

thanks guys I have replaced valve body and solenoids, I have no switches on truck , considered the unlock switch found on this site but after it was still locked after siting all night don't think that would help . sounds like new converter all though it only has about 10000 miles after rebuild with new half billet converter if the shop actually put in what they said. have checked or/bk wire seems to be good

I personally feel you roll the dice in a sense when getting a converter rebuilt by anyone other then the like of Goerend, DPC, Cascade etc... and most of those companies will only rebuild their own units. 

 

Although i don't know all the details of your converter, when I see half billet, I immediately start thinking a shop is blowing smoke up your a** and it's a quick way for them to make some extra money and do little to no work. I hope that's not the case and just my opinion.

Iyea half billet doesn't really jive with me either.  

Well I mean if you actually look at a converter it is only half billet on the aftermarket units. The back side is welded to the cover lol

truth.     regardless still think the TC is shot.  The tc can't lock in 1st as a result of fluid pressure.  So it should not possible to be locked after sitting all night in 1st.

 

 

theory at least.

the converter was new  replaced at trans rebuild , my local shops think in electrical, what in that line could cause this problem?I have had connectors off and cleaned, checked alt and replaced and checked again with a .000 and .003 result. Iam lost on this. how do you all feel about the GM solenoid upgrade any good

It is the converter.

 

 

The lockup happens when there is fluid pressure applied to the lockup plate in the converter through the input shaft.  The fluid cannot physically get to the lockup plate in  "p" "N" "R" or "1" on a stock VB.  The path for the fluid is just not there.  Doesn't matter if you have the lockup solenoid triggered. 

 

@Dynamic   can you grace us with insight? 

Electrical doesn't make sense either. Has to be a fluid/line pressure issue, or the TC itself is done.

 

For example, when driving down the road coasting, I can hit my lockup switch and nothing with happen. Once I get back on the gas with the switch still being held, nothing will happen. It's not until I'm on the gas AND THEN hit the switch that it'll lock and stay locked until I let go of the switch. That's the reason why you can have a lockup switch and accidently hit it when at a light and not on the gas and it won't stall the truck. Has to happen in a certain order, so I'd personally say that the electrical checks out. I don't know if TC can become fused together or stators fail or something causing it to be locked constantly but sorta sounds what you have going on.

 

What brand torque converter was used in the rebuild?

 

3 hours ago, jlbayes said:

Well I mean if you actually look at a converter it is only half billet on the aftermarket units. The back side is welded to the cover lol

 

You just couldn't resist hunh?! lolol! While I agree with what you're saying, have you ever heard of a 'half billet' TC?!?!

Edited October 10, 20177 yr by notlimah

52 minutes ago, notlimah said:

You just couldn't resist hunh?! lolol! While I agree with what you're saying, have you ever heard of a 'half billet' TC?!?!

 

I tried and failed LOL. And never have I ever seen one advertised as such. Advertisers are quick to leave details out like that.

Exactly why it made me a little wary of 'half billet' when I read that.

5 hours ago, notlimah said:

For example, when driving down the road coasting, I can hit my lockup switch and nothing with happen. Once I get back on the gas with the switch still being held, nothing will happen. It's not until I'm on the gas AND THEN hit the switch that it'll lock and stay locked until I let go of the switch. That's the reason why you can have a lockup switch and accidently hit it when at a light and not on the gas and it won't stall the truck. Has to happen in a certain order, so I'd personally say that the electrical checks out. I don't know if TC can become fused together or stators fail or something causing it to be locked constantly but sorta sounds what you have going on.

 

Ok belay my last on this one. I was wrong. The TC WILL LOCK even without throttle input. I tried it out and it does work, it just takes a bit longner then it does when on the gas. Confirmed it while coasting down hill, then again with it in drive, which in turn stalled the truck. ?

 

It DID NOT work in park. So this does still make me this hydraulic issue or TC is toast. Sorry for any confusion. ?

If you only have 10k on the rebuild, why doesn't it have a warranty?

On 10/10/2017 at 11:30 AM, Me78569 said:

The lockup happens when there is fluid pressure applied to the lockup plate in the converter through the input shaft.  The fluid cannot physically get to the lockup plate in  "p" "N" "R" or "1" on a stock VB.  The path for the fluid is just not there.  Doesn't matter if you have the lockup solenoid triggered. 

 

@Dynamic   can you grace us with insight? 

 

Close... Lockup occurs when the "release" pressure in front of the lockup piston is exhausted via the hollow input shaft.

 

When the converter is unlocked, it is being charged by the VB through the hollow input shaft. When a lockup is commanded, the solenoid closes, which strokes the lockup valve against spring pressure in the lower VB, which then sends hydraulic pressure to the inboard end of the switch valve (which has been regulating charge pressure to this point). This strokes the switch valve against spring pressure to the "locked" position which then reverses the flow of fluid to/from the torque converter. The fluid that was charging the converter through the input shaft (and holding the apply piston in the "released" position via hydraulic pressure in front of the piston) reverses flow and exhausts out through the VB, and the converter now gets its charge through the hub at full line pressure. This forces the piston against the front of the converter, locking the clutch.

 

A dragging converter clutch is most often caused by a failed converter, but I have seen a stuck switch valve cause the same thing quite a few times.

Iam back busy .  so no warranty because of 12/12 work was 22 months ago. so if the converter is bad would I find any thing in the pan when I pull it off? could the pressure solenoid cause this problem? the valve body was replace with stock about a month ago. 

the converter will work fine driving around town as long as it don't lock up, once it does it don't unlock when I stop unless I turn it off and sometimes it still does not unlock. does this help ?