Understanding the 4 gear lockup switch

[78oldscutlass]

OK, I have an issue concerning the 4th gear switch.

I did the modification of wiring the lock up solenoid where it only works in 4th gear (power comming in through the case connector, grounding through the 4th gear switch.

The converter will not lock up in 4th at all. But I locks up in 2nd and 3rd. I thought the switch is suppost to ground then pressure is applied to the 4th gear circuit or something? I bought a new one and its grounded all the time untill pressure is applied to the switch. So how does the switch actually work?

 

[HOTTOGO]

What you have is a N/C sw. (normally closed) and you need a N/O sw. (normally open) With your setup tc is locked 'til you hit 4th and sw opens to ground, with a n/o sw. it will not ground 'til 4th gear pressure closes sw.to ground. Is this the dia. you used?
http://www.aros.net/~rbuck/tech/4thgear.html if so it should be edited to say that.

 

[78oldscutlass]

Yes, that is the diagram that I used.

Has anyone had this same problem before? Is there a switch I can buy that is opposite of what I have? The pan is off now and I dont want to go back into it again and again.

 

[HOTTOGO]

Yes that is what I'm running right now. I just went to a local tranny shop to get a good used one, but it helps if they are the type of place willing to help a guy out. If you can't find one give PTS a call and tell him HOTTOGO sent ya.

 

[Nordbert]

N/O pressure switch GM #8627332

78oldscutlass- Check out GM part#8627332. I saw it listed in a thirdgen.org post for lockup wiring today. I also sent the # in an
e-mail to you.

 

[78oldscutlass]

Thank you Nordbert!

 

[HOTTOGO]

$12 here, usually cheaper than your dealer even after shipping, paste part# in search box. http://www.gmpartsdirect.com/
I paid $3 from my local shop for good used.

 

[78oldscutlass]

I work for a GM dealer and I got for 12 bucks also.

 

[HOTTOGO]

Cool! lucky you, was that your price or for the guy off the street as well?

 

[78oldscutlass]

Originally posted by HOTTOGO
Cool! lucky you, was that your price or for the guy off the street as well?

Employee Discount

 

[HOTTOGO]

Ahhhhhhh!

Okay, I thought maybe?!

 

[Clay Thompson]

Brain fart?

When you wire the switch in I would recommend including a ground run all the way out to the plug--just pull a wire off an old plug by inserting a minature screw driver in the holding slot or use the existing wire if it is already there.

That way it the switch fails or does not work you can at least have a manually-switched lockup until you are in the mood to remove the trannie oil pan again.

I wired mine exactly as the diagram shown in this post--I thought, but could have had a brain fart in the middle of the install--but the trannie would not lockup. Lucky for me I had kept the ground in the plug connected and just used a switch. One day I'll pull the pan and try to figure out what's wrong.

 

[78oldscutlass]

The switch was exactly what I needed. The lockup works like it should in 4th gear only now.

THANKS ALL!



Sonny