Have recently replaced a 5.7 diesel with a 6.2 engine to a 350 tranny. There were no wires, hoses or anything attached to the gearbox before swapping engines, so I need some help to find out what's what (solenoids, vacum modulator etc) and what's needed for proper action and how it should be connected to the engine, I'll survive without the kickdown function for instance. As it is now the truck sometimes wont shift up with the lever in drive. Would be grateful for any help as my repair manual doesn't cover this topic much and I'm not very good with automatic transmissions either!

If it were a gas engine you would hook the vac modulator to the manifold vacuum. Plus the kick down cable goes right next to the dipstick tube, which hooks to the throttle.

As I understand from reading here, diesels don't have vacuum.

If it were a gas engine you would hook the vac modulator to the manifold vacuum. Plus the kick down cable goes right next to the dipstick tube, which hooks to the throttle.

As I understand from reading here, diesels don't have vacuum.No expert here, but I have hooked up several TH350's. The kickdown is more of an added bonus as you can manually downshift with the selector. With no vacuum at the modulator it will cause irradic shifting. I know some diesel engines have a vacuum pump to operate vacuum controlled power brakes (if not hydro-boost equipped). The problem is a non boosted engine has varying levels of vacuum depending on engine load and is part of the equation when telling a TH350 when/how to shift, whereas a vacuum pump (I would ASSume gives a pretty steady vacuum signal)...

If nobody here can help, you can contact a local tranny guru or even try posting over on www.ck5.com (http://www.ck5.com/) as I know others have run this engine/tranny combo.

I've got a vacuumpump, vacuum modulator on the tranny, but as I've got some tips, I need to connect this to a vacuum regulator valve mounted on the injectionpump. I spoke to the guy i bought the newer engine from and he said he had run a 700r4 which is electrical operated, hence the VRV is replaced by some kind of variable resistor on the IP... Feel free to correct me if I'm wrong. Perhaps I can get a VRV at the junkyard or so and get it working? Parts aren't cheap or easy to find overhere as for you lucky bastards ;)

You definitely either have to have the VRV or else go with a cable operated modulator. They were common on diesel trucks w/bigger allisons. Go to a tranny shop, they have the VRV and can get the cable unit, but they cost more than the VRV.

Got hold of the VRV... Now the tranny shifts as expected. Still I'm curious what the electrical connectors on the tranny are supposed to be plugged into? Have one on each side.

Many thanks for enlightning me in the dark art of automatic transmissions ):h

Do you know the year of the trans? If it is '80 or newer, it has a lockup torque converter. The connector is the one on the drivers side. Some of them had a pressure switch on the passenger side near the front. The lockup connector can have up to 4 terminals. You need to hook it up to get the best mileage and keep the trans cool. It can be done with a switch on the dash if the vehicle doesn't have wiring for it.

Not sure but I think it's a '81 and it's said that it has a lockup function. I'll try to get a wiring diagram for this, as I'm not too comfortable with flipping switches for different things while driving.

Thanks again

There is a pressure switch on the valve body that controls the speed at which lockup occurs. It is operated from the governor circuit. A toggle switch on the dash works okay, because you mainly leave it on. It will lock and unlock according to speed, but has no input as to load. Usually, the converter unlocks under no load, under full throttle, and when the brake is pressed. The dash switch is simply an override to be able to turn it off if you want to. We had an Olds wagon that was an ex-diesel that we drove for 12 years that way.

Ok, so this pressure switch is it maybe a (don't know what else to call it) 2pin "flat tab" thing located on the right (drivers side) of the gearbox infront of the dipstick tube? See picture!

The pressure switch to engage lockup is inside the pan on the valve body. The switch you are seeing is for something else, you won't use it. You will connect to the electrical connector on the other side of the trans, about halfway back . If there isn't one, it isn't a lockup.

Ok, the other side looks like this. I also noticed a small plastic tube about 5/8" in dia. facing left on the top of the trans, but i suppose that's just a vent.

How many terminals are in the connector?

Two, but there's just one pin. As far I can see it's factory made this way.

Run 12V to that terminal from a toggle switch and you are in business. If you don't like the speed that lockup occurs, there are lots of different pressure switches available to change it.

Ok, I'll look into it later, thanks for helping!