Do manual trans have a transmission relay?

Manual 5VZ-FE here. Just saw a transmission relay. Is this to switch between 2x4 and 4x4?

 

I think we’re gonna need more context

 

what did it look like?

 

I'm gonna take a wild guess that it doesn't have free wheel front hubs.
YES
It actuates the Automatic Differential Disconnect after 4wd is selected by shifter or button.

 

It's behind the passenger kick panel.

 

Like a relay. Behind passenger kick panel.

 

How do I tell between free and nonfree front hubs?

 

Well that was helpful. How do you know it was for the transmission then?

 

It says right on it.

 

Free wheeling front hubs, also known as Locking hubs or Manual hubs have turn to lock vs.
ADD has plain caps and the CVs are always turning as the lock is inside the front differential.

 

nothing in a manual trans will require a relay, it never have and never will. It’s likely a contact driven off of a detent switch that feeds other logic.

 

Sounds like he found the 4wd ECU
Module

 

behind the power windoors plugs

 

This is correct. "transmission relay" is misleading, it is for ADD function in the front diff.

 

So, this connects to the big cylinder under the driver side wheel well behind headlite? Or is that something else?

 

No, but related.
From what you have mentioned so far, you have an ADD front differential not manual/free wheeling hubs and a vacuum actuated ADD actuator, later years were all electric.
In simple terms, engine vacuum is used to internally "connect or disconnect" the front diff. There is other stuff going on but that's the basics.
When you shift into 4wd a switch on the transfer case energizes the transmission relay. The relay controls two "vacuum switching valves" that direct vacuum from one "VSV" or the other to the ADD actuator on the diff. Sounds complicated, but it's really very simple.
The "cylinder" is a tank, merely there to act as a vacuum storage/accumulator device for periods of low engine vacuum.

Relay at the top, VSVs' at the bottom. ADD actuator and vacuum line/tank not shown.


ADD VSV location.

 

I ran into those yesterday and was wondering what those were as well. thx for the explain

 

Hello, I see you used the trans relay on a prerunner, im doing the same for my 04 j-shift with a.d.d. Which pins did you use for power, and landing on the actuator?

 

You may have meant to quote the OP of this thread, I believe he was the one doing the 4x4 swap. I'm sure Mr Pool could answer your question, although I'd be surprised if he swapped his truck from 2WD to 4WD.

The info you need is on the wiring diagram you posted on the other thread, as well as the picture of the relay connector pin numbering above. Power to the relay is via a switchable ignition source to pin 3, which is junctioned with the lead from pin 9 and goes to the positive lead on the 4wd position switch on the transfer case.

For the ADD actuator, you just need to ensure that the leads/pins match the diagram below, i.e. pin 1 on the control relay matches with pin 5 on the actuator connector, etc.



Re-posting the pin/lead identification for the transmission control relay here for completeness (wire colors are from the factor harness, and match the colors in the EWD above):

Transmission Control Relay pins:
1 - ADD motor (red-black)
2 - Ground (white-black)
3 - Ignition power (black-yellow)
4 - ADD motor (blue-yellow)
5 - ADD limit switch (blue-red)
7 - Ground from transfer 4wd position switch (white-black)
9 - Power from transfer 4wd position switch (black-yellow) (junction with pin 3)
10 - ADD limit switch (light green)