WTH are these senssors

Hey I am doing some work for my neighbors 98 Tacoma 2.7 5spd 4wd, and I found a few sensors and connectors that are missing.
I was wondering if you guys could let me know what they were for and if they are essential.

The first one is on the wiring harness and is by the alternator.
The second one is under neither the truck sort of by he master slave cyl.
The third is underneath the truck sort of by the bell housing.

thanks guys.

 

Well the middle pic is your bleed valve for your clutch....as far as the other 2 go if there isnt anything right there to plug it into i wouldn't sweat it...on my trucks there are a few random unused plugs that woulda been used for different options i dont have, could be your case aswell? Since there isnt a long length of wire utilized on most plugs if there isnt a plug to connect to right close its prolly just an unsed part of the universal harness.

The one down by the front diff...does the 4wd light come on when 4x is engaged? Could be that? I guess if it dont have a femal plug to stick it into around there i suppose thats not it though...

 

The last picture im pretty sure is the wire that runs you 4x4. I found mine ripped off and had to solder it back together for my 4x4 to engage.

 

Actually i believe thats just the sensor that lets the computer know add is engaged. theres one on top of transfer case too.


1st one looks factory capped. Toyota does that alot and uses the same harness for differently equipped vehicles. does truck have ac?

 

Thanks for the reply's guys.
Yeah doh i looked at the middle one from the top and realized it was the bleeder shortly after i posted LOL.
Yeah it does have ac.
Hmm as for the 4x4 it still engages but the light doesn't light up(any idea of the name of that sensor?) Anyone have any idea why that would be cut? It looks cut to me and the cut is almost to the top of the wire so it looks intentional.

Thanks

JP

 

The 4x4 system doesn't engage/disengage the transfer case and add system at the same time. the transfer case wont disengage until it senses the add has been.

That sensor may be faulty and made it so the computer thinks the add is still engaged and so the transer case wont disengage. the wires could have been cut to get around this issue. only downside is the 4x4 light wont come on.

I believe the sensor or "switch" only costs about $25 if he wants to get the light working again.

 

So if the computer thinks the ADD is still on and wont let the transfer case disengage would it stay in 4wd(high or low)? It has a horrid shutter when going 45-55ish but I really thought the issue was related to a rough idle issue i am dealing with.
I am not a professional mechanic by any means but I enjoy helping friends and neighbors out who don't have a lot of money but need there cars fixed.

 

The shutter is most likely bad alighnment, tires nit balanced,or maybe a bad u joint.

What you could do to check i jak up the front end and make sure your wheels spin seperately. If so they are disengaged

 

Since front diff is open it will just spin the spider gears so even though front driveshaft is spinning your still in 2wd.

As is the transfer case should be disengaged so your vibs are more than likely not related.

 

Ok i tired it and the wheels move freely. The 4x4 seems to be working still but no light is all.

Ha wish i had tried that before going into the other issues inside the engine, but it still had a rough idle so not sure its tire/alignment/Ujoint.

But I guess it could be both that and engine related.
I check ujoints they were good. I replaced the center carrier because it was squeaking like crazy and checked u joints while i did that. But I cannot balance or align without taking it to a shop.