I have a 88 vert with a chev 4.3 and a 700r4. What I want to do is find a output, connection I can use to engage my at lock up. I currently am using a manual flip on/off switch wired to the solenoid in the trans. I was thinking there may be a way to use the cruise control to either get a voltage or ground output to use to enable a relay to activate my lock up. The car was a na. 5spd vert. Thanks

 

I don't' own a automatic car.

But the wiring diagrams show a Lockup solenoid (on the transmission) controlled by a Lockup Relay and a vacuum switch (located close to the stk boost/pressure sensor.

And pin 1I on the ECU is in control also. It appears that pin 1I puts a ground on a wire. That wire goes to the vacuum switch........thru the vacuum switch if the switch is made...........on to the Lockup Relay where the gnd from pin 1I is put on the Lockup Relay to pull it in.

It pulls in and a set of contacts internal to it make and send power on to the Lockup Solenoid on the automatic transmission. That power comes from the Engine fuse which is switched voltage whenever the key is put to ON or better.

That's more or less how it works on a stk RX automatic car.

I THINK SATCH owns a automatic car and might add to this.

So the Lockup solenoid is controlled by the ECU output and whether or not the vacuum switch is made or not and the signal from the ECU is a gnd signal. The gnd signal is used to put a gnd on the Lockup RElays coil. That coil has power waiting there on it's solenoid anytime the key is ON.

What causes the ECU to output a gnd on pin 1I is unknown to me. I didn't look far enough to see what that is. Satch knows.

 

The vacuum hose which runs to the Pressure Sensor is teed and sends that source of vacuum to the Vacuum Switch also and I believe it is the vacuum level in this hose which dictates whether the contact in the switch closes or not.

 

Thanks HAILERS2 for the quick reply, I don't know if Mazda used the same ecu for both the 5 speed and auto trans. My concern with the 700r4 is the speed it needs to be disengaged as not to damage the converter . In most auto's I have found most to engage at or near 40 mph and disengage at or near 30 mph. This is why my interest is in the Cruise control . If the cruise is on it will not engage until 30 mph and it will disengage anytime the Brake is used. I have considered checking the actual unit's inputs during operation to get my connections, (the vacuum operated cruise control unit) clip into the connections and observe the meter during operations. Any suggestions/observations urged. Also I don't know SATCH . Thanks again

 

The ECU's are the same.

 

There is no seperate ECU for the automatic car. BUT there IS another computer called the 4AT Control Unit dedicated to the automatic transmission. Frankly when I started lookiing I fully expected the Lockup Solenoid be be controlled by that 4AT Control Unit. Not so.

Satch replyed to your post. Seems you were writing when he was answering ....according to the times the two posts were made.

I probably won't look any further. I don't have much interest in it. Looks like that car should FLY! No lack of torque at the stop lights for sure.

 

Well I stumbled around a bit more and see I was not quite right in my first reply.

It seems the ECU isn't the one putting a gnd on the Lockup Relay but PROBABLY a OD oil pressure switch in the transmission (see 2ND jpg attached and the bottom of that jpg).

Seems the 4AT Control Unit also gets this gnd signal along with the stk ECU.

So it seems like Satch said in his post, the vacuum switch plays a major part in when the Lockup relay gets a gnd put on it (which in turn puts power on the lockup solenoid). Correct me if I'm wrong.

I need to quit right HERE.

 

Couple thoughts:

Why does your car have the stock ECU when it's got a transplanted engine? What's that stock ECU connected to? And will this stock ECU still put out the lockup signal without the proper engine hooked up to it?


Alternative method of making a lockup circuit might involve a little bit of electronics knowledge, but I think the gauge cluster has a pulse output from the speedometer.

 

Thanks again to HAILERS2 and Satch for the info Pele, the reason the Ecu is still in , is we were advised to leave it and use the existing wiring in our connections. This info came from Granny's http://www.grannysspeedshop.com/ . They make a mount for any type of engine change over and transmission. Thanks to you Pele , I rechecked the site and found the wiring connections for it there. You may find some info there useful they have all the wiring defined at the connections and colors.