decided on adding a manual switch for OD, how do i?

[Oldskool153]

So im thinking i may reconnect my OD and wire in a switch as many of u have sugested, at that point I should be able to control it even if the closed loop threw the ecm isnt closed? like for example I have a bad 02 sensor so it breaks the closed loop with a fault code and my OD starts actin funny when i let the ecm control it, with a switch i can still manually control the OD engagement disengagement even if the closed loop circut is broken right? my next question is how hard is it to do this? and does it involve my removing the transpan>? or can i go right to the wires on the shift switch?

 

[gmhowe]

Thats what I did on my 85, bought a toggle switch for about $4 and hooked up the switch wires and fastened on the left side of the console by the heater controls, but mostly I just leave it on all the time.
Gordon

 

[vetteoz]

with a switch i can still manually control the OD engagement disengagement even if the closed loop circut is broken right? my next question is how hard is it to do this? and does it involve my removing the transpan>? or can i go right to the wires on the shift switch?

No internal works; all you need is a switched supply to the O/d solenoid.

As it appears your relay and wiring were OK, all you need is a switched 12V fed to the control side of relay on firewall , replacing the control wire from ECM.

Or
remove the relay altogether and switch the in / out wires from the relay.Use same gauge wire as this is direct feed from battery

The switch on shifter DOES NOT operate the O/d.

It sends a signal to the ECM to operate the O/d.The switch is not heavy enough to handle the current required for the solenoid.

 

[Oldskool153]

thanks guys. 2 more things, once i put in a toggle will my OD still come on if the closed loop is broken as long as i switch it to on? and also were is my selonoid relay? i have heard on the firewall and I have heard on the inner fender? mines an 88

 

[tequilaboy]

The ecm activates the O/D by providing ground to the O/D relay pin B.

A manual switch would simply need to ground pin B for activation and to open the circuit between pin B and ground in order to deactivate.

This applies to 86, but its close enough to describe how the circuits work.

http://members.shaw.ca/agent86/OverDrive Electrical.pdf

 

[vetteoz]

The ecm activates the O/D by providing ground to the O/D relay pin B.

Old age creeping up; 5 years since I pulled my 4+3 for a auto :bash

 

[Oldskool153]

can anyone whos added a toggle switch please contact me? I want to craw under my car, plug the OD back in and than add a toggle swtich this weekend (weather permitting). I do not have an FSM and pretty much I kno the concept of how this is gonna work but im not sure where the wire needs to go on the relay, where i need to ground it or even where my relay is for that matter.. Do i need to buy a new relay to add the switch?? How long of a job is this? Also this might be a dumb question but my OD has been unplugged directly from the unit for about 150 miles, if i plug it back in will it hurt anything?