What is this on my Tacoma?

Just some pictures of things that I don't know what they are or go to.

Under drivers seat:


Under vehicle behind rear driver side wheel:


Mounted near drivers side bumpstop:


And terminates on rear axle on passenger side of diff:


What are these things?

 

The last one looks like a brake proportioning valve....

 

I was thinking something like that but what is with it going over to the other side of the axle? I've not seen anything like that before.

 

Last two are the LSPV and the rod that actuates it.

Not sure what the first one is, maybe for the seat belt warning buzzer?

The second one looks to me like something a previous owner added.

 

The way it worked on the older trucks is as the suspension squatted down, e.g. as you increased the cargo, the rod would push the valve open more and more which was supposed to increase the proportion that the rear axle contributed to braking. With an empty bed the rear is supposed to have very little brake fluid traveling to it. The way you adjusted it was to find a gravel road and slam on the brakes. You would adjust the threaded side of the rod up and down until you find the point the rear locked up and then back off a turn.

 

The second one I thought would be stock, perhaps for trailer.?

 

The wires under the seat could be for a JBL amp? It looks like where my wires are coming from. Also could be seat buzzer.

 

What does the weight or yaw sensor do?

 

The weight sensor would make the seatbelt indicator on your instrument cluster go crazy because it thinks you have a passenger in the seat but really it's just a backpack or something heavy. 1st gen Tacomas don't have this feature, that connector is for the seatbelt buckle. When the seatbelt buckle is engaged it completes a circuit and turns your seatbelt light off.

 

Then it must not be that. It is under the drivers seat and I have a 1st gen.

 

I know, just telling you what a weight sensor would do. I have the same connector and it's for the seatbelt buckle circuit. Was in unplugged in your truck?

 

Yup. I briefly looked at my seat and didn't see a corresponding plug. I'll look again more diligently.

 

Is your seatbelt light not on? The harness is actually located on the seatbelt buckle not the seat, look near the bottom of it.

 

I don't recall it being on. I'll look when I can. Thanks!

 

If you don't care about the seatbelt light you can just jump the connector to truck the cluster into thinking the seatbelt is engaged - don't quote me on that though.

 

first one is the seatbelt sensor.
If you don't buckle up, the dash seatbelt light indicator will be on, reminding you to wear your seatbelt. Connects to a cable that sticks out from under the driver's side female end of the seatbelt

second one
Not sure, but could be wiring for a trailer of towing connector that may have been removed?

third and fourth ones are the LSPV
Load Sensing Proportional Valve. What it does, basically, is adjust the rear braking power proportionally to the load you are carrying in the bed of the truck. When loaded, the bed and suspension lowers, the rod pushing a little piston inside the valve, increasing fluid pressure to the rear brakes.

 

This must be your first Toyota...

Every Toyota truck/4Runner I've owned is designed essentially this way. As to why it's designed like that vs. other designs, I couldn't really say, as I'm not really familiar with other designs.

I'm sure if we got a bunch of Ford/Chevy/Nissan/Toyota engineers locked up in a room together, they could figure out why.