How wire 2nd gen column shift overdrive button in 1st gen
 

I've read in the past about some 1st genners using a 2nd gen column shift (with overdrive button) to activate overdrive in a A518. The 2nd gen OD push button is a momentary switch and will engage OD when depressed, but will disengage OD when it is released. I think I need to wire in a latching relay, but can't find any diagrams etc for this. Can someone please direct me to this information. I asked this question in another thread on governor pressures, but that thread went nowhere. TIA

It is a momentary switch just like the one on the dash. All you have to do is wire it in parallel.

Thanks cougar! I don't understand. I want to push the column shift OD button and have it ground the OD solenoid and keep it grounded after I release the button: and, if I push the button again I want it to unground the OD solenoid and keep it ungrounded until I push the button again. Is that what you are saying would occur if I wired the OD button in parallel with the dash OD lock out button?

i believe you want a toggle. i did this in my cummins swap project with an a518. you just wire one side to ground and the other side to the solenoid. "on" and it will act as normal "off" and it will not shift into overdrive.

Attachment 49248

If I'm not mistaken, there's a thread in The Sticky regarding what you're wanting to do.

j.fonder, that is what I'm trying to do. Presently I control OD using a toggle switch on my lower dash, but I have to lean forward and reach for it everytime. Thats why I wanted to use the 2nd gen shifter. Did the shifter in your picture come with that toggle switch or did you install it? If you installed it do you recall where you bought it? Thanks

What you want is a push on/push off switch, not a momentary. Which means you cant use the shift lever button unless https://www.dieseltruckresource.com/...nction-315554/

Sounds like you need a simple impulse relay to make it do what you want.

Thanks again, cougar! I've found some latching relays which would allow me to use the 2nd gen momentary push button, but I'd rather use a rocker switch like you and avoid more electronics. That's why I was asking about the rocker switch in your picture.
Was it OEM and if so what truck/car had it. I've found a bunch of aftermarket rocker switches on EBAY which are close fits and I suspect that's what you used. Please inform me. By the way, bro, I lived in Alaska for 17 years, in Port Armstrong on Baranof Island, 100 miles from nearest road (Sitka) brownies big as our trucks (not quite) - best years of my life despite nearly starving and living on clams one severe winter. Thanks for the help!

RedNeck that's a great idea, and I've ordered one http://www.bakerelectronix.com/products_plrc/ This latching relay can continuously sink 2.0 amps to ground, and handle up to a 3.0 amp surge.

I don't know how many amps it takes to ground the OD solenoid and hoping it's less than 2 amps. Does anyone know? Thanks again!

I wired mine just like the sticky said. All it does is add another button (on the shifter) and I use it just like the one on the dash. And can still use the dash button as well.

I finally found that sticky - it was in a thread about a tach install. Regarding the method described in the sticky I assumed since I don't have a TPS anymore, the computer could no longer control the overdrive shift. Maybe I overthought things, but that is why I went in search of a latching relay. I've already ordered a latching relay and plan to use it - and bypass the computer altogether. Could I have used the computer, as in the sticky, even though I don't have a TPS? Also does anyone know how many amps it takes to ground the OD solenoid, the relay is good for 2 amps continuous? Thanks

The switch in pictures 4 & 6 looks to me to be a vacuum machine switch.
You could let the latching relay operate a second relay like used for the air conditioning on our trucks.
Mike

I don't have a TPS either. I have some diodes wired in instead. Mine works fine still.

If your truck is 92/93 - splice one of the second gen lever OD switch wires into the OR/WH into the OD module & ground the other wire.

If your truck is a 91.5 - splice the lever's switch wires into the YL/DB and YL/BK on the OD module.

The above will let you use either the dash mounted factory pushbutton or the second gen lever button as they will be wired into the same circuit.

J.Fonder used the toggle switch wired to the OD solenoid as his '03 doesn't have the first gen OD module under the dash.