Engine/Transmission (1994 - 1998) Torque converter wont unlock

[Jschafer]

Turned the corner tonight and the truck luged came to a stop and it stalled.

If I start the truck it stalls when i put it in gear.

I played with the ovetdrive button no help, traced my converter lock up switch no problems there. Is there a selenoid that controlls lock up or what does.

Thanks in advance for the help

Joe

 

[DBraunig]

The lock up/overdrive solenoid assembly is inside on the valve body. you will have to remove the valve body to replace it. Try disconnecting the plug on the trans 1st and see if it still stalls when you put it in gear. you should lose lock up and overdrive with the connector unplugged, but it will let you know if the solenoid is stuck, or you have a wiring/pcm problem forcing lock up. If it still stalls when the connector is unplugged then the solenoid is stuck and will have to be replaced.



Hope this helps,



Dave.

 

[Jschafer]

Dave, I unplugged the three wire plug just above the pan in the area of the temp plug after un plugging the truck wouldn't start so I plugged back in and started the truck then un plugged while running and it still stalled when I put into gear. If I read you correctly then it should be the solenoid.



Thanks again

Joe

 

[DBraunig]

Joe,



i think you unplugged the neutral safety switch, it plugs in horizontally on the case right above the pan. Right above that switch and to the rear a little bit, there is another connector that plugs down vertically in the case. This is the lockup/od connector. try unplugging it instead. the truck should still start with the lockup/od plug disconnected.



Dave

 

[CSchafer]

Dave

Thanks again I will check that this morning

Joe

 

[Howard Durand]

Joe,

If the solenoid in the valve body is defective, I have one you can have real cheap.

I removed it from a working VB that I returned as a core replacement after installing a new, enhanced valve body several years ago.

I would be more inclined to think you have a ground somewhere in the TC circuit. If you have a volt-ohm meter check the cable. One of the wires will have 12 volts on it with the switch on and the other two are the ground wires. One for OD and the other for TC lockup.

The PCM grounds them when calling for OD and or TC lockup. Check them against ground with an ohm meter. Neither of them should be grounded.

 

[biggy238]

could the relay have failed?

 

[Howard Durand]

The relay could fail and either cause the TC to remain locked up all of the time or never lock up. Depending on what actually happened.

Whatever happens when he disconnects the control cable from the transmission will determine where to look for the problem.

He said this happened when he turned the corner which would lead one to think that something moved and caused the problem.

There is also the possibility that the PCM failed but I would think it is more likely a cable problem. The cable runs from where it connects into the transmission, straight forward and up into the loom that runs across the firewall,then on to the PCM.

If you are using a switch to lock the TC, make sure there is no problem there.

Switches have been known to fail too.

 

[Joe G.]

The trans is a 47RH. It should not lock up at all in 1st gear. Turning the switch on or having a short should not lock it up when the truck is stopped. That will lock up a 47RE. I and flip my lockup switch with the truck stopped. It won't lockup until it shifts to 2nd. I suspect that there is some sort of mechanical problem. I hope it's just something electrical but don't think so. If something is wrong with the trans so it starts in 2nd it might lockup at a stop.

 

[Jschafer]

I unplugged the wire from the plug this morning and it still did the same thing. The torque converter seems to be locked in when running it will stall if put in reverse or forward. When my mystery switch gets turned on by accident the converter wont lock until after the truck is moving. First thing I did was to take the mystery switch out of the system, I didn't check the plug for a short to ground but I think with it unplugged it would be unlocked if the wiring or computer was at fault. I think (that usually gets me in trouble) :-laf



After I pulled the plug this morning and it didn't change anything it went to the trans shop to have the solenoid changed the new one will be here in the am I will let you know what happens.



Howard

I wish I would have got your post earlier as i would have taken you up on the sale.



Thanks again guys this is a great site

Joe

 

[Howard Durand]

Pulling the control cable should answer a few questions. As far as being locked up when coming to a stop, mine would be shaking so bad I would be shifting into neutral before it ever had a chance to get to 1st.

Joe G, you know these things pretty well, what would be the occasion that would cause it to mechanically lock independent of the electricals? Would it be in the valve body?



PS



The answer came while I was writing this reply. Hope a new set of solenoids solve the problem.

 

[Joe G.]

Once you manually lock it, it will stay locked and kill the engine when you stop if you don't unlock it. However, it will not lockup just sitting there in gear if it was not already when you turn on the lockup switch. Also, as far as I know, there is no way a bad solenoid could cause that. This behavior was explained to me as being because of the switch valve. It has three lands in a 47RH and four in a 47RE. That appears to cause the lockup fluid circuit to share pressure or something like that. If you turn on the switch in a 47RE it will kill the engine just sitting there in gear. I don't think a VB problem could cause it unless something got plugged up. Maybe. I suspect something broke and jammed the TC clutch so it can't disengage. Hopefully I'm wrong about that. Maybe a transmission guru will chime in here with a better opinion than mine.

 

[CSchafer]

Well it is not the solenoid, the trans will be on the bench by morning, at guess we think the tc took a crap I will know tomorrow.



I will start a new post but I need to have some suggestions on a new tc

The one in the trans I think is a Dunrite I am not sure it was sold to the trans shop in 2000 by TST if any body knows what they were using back then please chime in. I will send mark an E-mail but no idea if I will here back.



Joe

 

[Jschafer]

The problem was a worn out spool (valve) in the valve body, fluid would leak past and lock up the converter.

After looking inside, the trans was due for a rebuild anyway

Thanks for all the help

Joe

 

[MPlunkett]

J Schafer...



My truck is doing something very similiar..... When at a stoplight, the truck wants to go forward with my foot on the brakes. Then it gets kinda jumpy and stalls. It will start no problem... ... When you put it in drive, it dies... ... Does this sound like what your truck was doing?... ... I sure hope I don't need a new VB or a new transmission :{ If this sounds similiar please let me know, I'm taking my truck to the shop on mon after a week at the dealer with no luck. Ps my transmission fluid is nice and purple, not burned at all ... ... Dealer tried to sell me a new ECM... .....

 

[Jschafer]

Yes it is the same thing mine was doing. Your transmision is different than mine if it is on your 98 you have a RE more of the trans is controlled by the computer on yours. But one of three things is happening, (1)the trans is getting a signal to lock up be that a short a computer - something electrical, (2) the valve body spool (valve) is stuck (3) the TC is messed up.

Joe