Gear vendors overdrive question

[Keith 01]

Hello, and thank you in advance for your input.
I have a ls1 in a 2001 Silverado.
I recently installed a th400 with a gear vendors overdrive.
Added a vss from Dakota digital at the cable speedometer output.

I understand that it is s hard on the overdrive unit to be engaged when in reverse or at low speeds.
I plan on manually triggering the overdrive with a button.

My question is how to go about finding a speed sensitive circuit that I could use to trigger a relay, allowing power to the manual switch.
For clarity, I’d like to make it impossible to turn the overdrive on when in reverse or at low speeds.
Edit- I believe the truck has a 411 pcm installed, if that is relevant information.
Again, thank you in advance.

[gtstorey]

I don't think this is possible with a stock pcm. It would take a Ardurino programmed to do it. Nothing for a direct relay.

I think GearVendors has a unit that can take a speed signal and does what you want.

[twenglish1]

It would be a significant cost at this point, but the 4l80e is essentially an electronic/overdrive version of the th400, also designed to work directly with your Silverado PCM, you will also gain TCC lockup function, and the advantage of being able to tune shift pressures and shift points electronically.

[pdsq98gt]

If the pcm still thinks it has an automatic you could use the TCC solenoid enable circuit to ground your relay. Then set your TCC speeds to the speeds you want to be able to enable the Gear Vendors OD. Hell, you could probably use the shift tables to automatically turn the OD on and off.

[blindsquirrel]

If the pcm still thinks it has an automatic you could use the TCC solenoid enable circuit to ground your relay. Then set your TCC speeds to the speeds you want to be able to enable the Gear Vendors OD. Hell, you could probably use the shift tables to automatically turn the OD on and off.

A lot of that wouldn't work without a real, complete transmission attached to the other end of the wires. Codes will set which disables the outputs, and disabling the codes doesn't solve it either. If it can't monitor return voltage coming back through the correct solenoids it won't ground the control pins.

[abc]

Why would they say it's not acceptable to run at slow speeds? looks to me like they made it more bullet proof than just about any street going transmission/transfer case.

They advertise it as a over drive/under drive unit to split every gear. If your gonna engage it with a manual switch you could add a gear position switch that will only pass a circuit when you desire, such as the way a reverse light switch works on older vehicles or even the gear selector switch on a 4l60e.

[gtstorey]

Why would they say it's not acceptable to run at slow speeds? looks to me like they made it more bullet proof than just about any street going transmission/transfer case.

They advertise it as an over drive/under drive unit to split every gear. If your gonna engage it with a manual switch you could add a gear position switch that will only pass a circuit when you desire, such as the way a reverse light switch works on older vehicles or even the gear selector switch on a 4l60e.

IRC it takes a certain rpm/speed for an internal pump to lubricate.

[pdsq98gt]

A lot of that wouldn't work without a real, complete transmission attached to the other end of the wires. Codes will set which disables the outputs, and disabling the codes doesn't solve it either. If it can't monitor return voltage coming back through the correct solenoids it won't ground the control pins.

You could make a box with 24 ohms of resistors to simulate the shift solenoids. They would have to be able to handle 1/2 an amp each so it might need a heat sink. It might not be worth it. But would be nice to not have to throw a switch every time you wanted OD.

[Keith 01]

Could I simply make a box containing the actual shift solenoids from the original 4l60e solenoids as resistors? A transmission emulator?

[Keith 01]

IRC it takes a certain rpm/speed for an internal pump to lubricate.

As I understand it, there is an eccentric that drives an oil pump. When the unit is not activated, the oil is merely recirculated.
Applying voltage to the solenoid moves a valve, directing the oil pressure to an oil circuit that applies pressure to a clutch.
At low speeds, this insufficient oil pressure will result in low clutch pressure, slipping the clutch.
This will result in premature wear.

[gtstorey]

https://gearvendors.com/install.html

You need to contact Gear Vendors and discuss their "autodrive" feature and see if you can add it to your setup.

[Alvin]

It feels like last century since I messed with one of these but they were always a switch on the shifter somewhere.. Most of the time the engagement is very harsh and I don't think I would want that happening automatically.

[edcmat-l1]

Last one I did used an old style floor mounted dimmer switch to turn the GV on and off.