t10032bf

took it mudding and then it sat for the winter now it wont engage

millball

Engine and transmission type?? manual locking hubs???

Jeremy Johnson

I recently bought a 97 where the 4x4 didn't engage and it turned out to just be the vacuum switching valve needed to be replaced, easy $25 fix.

Here's a picture of what they look like - https://cimg7.ibsrv.net/gimg/www.yot...eb92891893.jpg

Mine was all rusted out (as you can tell) so just replacing that one switch fixed it

Tilikum102602

Im in orem utah with 4 T100s. Hit me up i have lots of know how for these things. My dads doing a rrar mount turbo on his and im supercharging mine. Reply and tell me what you need and what your looking for.

shredwhiteandblue

The problem with mine was the actuator and it's very common. There's a forum online about bypassing this (ie. locking the actuator's collar into 4wd position) and getting a set of locking hubs. Has been working fine for me.

Tilikum102602

I bypassed mine. And honestly i just run it like that. No need for manual hubs for me yet anyways, because ever time i shift my tranny into 4x4 its instantly into 4x4.

97T1004ME

My 97 T100 V6 SR5 does nothing when I shift into 4wd. This problem started over a year ago but with winter bearing down I NEED 4wd ASAP. I have cleaned the front actuator switch, checked the oil in the front diff. and made sure there is vacuum pressure throughout the ADD system (which is the case). When I shift into 4wd the dash light does not illuminate and as far as I can tell nothing in the vacuum system changes. This leads me to believe the wiring from the shifter is compromised and wanted to know what that wiring bundle/harness is called in order to reference it when/if I bring the truck in. Also, does anyone know of a source for a free online service manual for this vehicle? Thank you!

Tilikum102602

Pull the actuator off. Slide the ring over in the dif and the fork over on the actuator , put on a clamp, and you will have 4wd as soon as you shift into it

Tilikum102602

If you don't know how ill do it on my dads T100 and post pics

t1oo

The manual hubs are for the increased fuel economy from not having the axles rotating when not in use.

t1oo

That front electric switch is just for the 4wd indicator light on the dash. What you need to check is the vacuum actuator on the front diff. You probably have a vacuum problem preventing the actuator from engaging the 4wd. I bypassed the vacuum system by opening the vacuum actuator, drilling a hole through the diaphragm and housing and putting a screw through the diaphragm fixing it against the back wall of the diaphragm housing.

97T1004ME

Thanks guys, I have vacuum pressure at the front dif. and I checked the ADD switches (which have continuity and vac pressure, so I think it's electrical. Could someone post a link or show how to bypass the ADD system?

t1oo

Tilikum102602

Ill do it to my dads T100 when i get off school because i already did it on my T100. Ill take pics and post them here and also on a new forum

Tilikum102602

I have the step by step on how to do The ADD Delete below. All photos and everything below i did myself so ( f u copyright)

My Dads 96 5vz 5 speed 4x4 288k. Its about to get painted , thats why its all sanded paint.

My truck. ADD delete i did on it right before Thanksgiving and i Have put 10k miles on it since. So works great and no issues. 1993 T100 3.4 5 speed 4x4 320k miles.
Grab an oil pan and drop the skid plate, its held on with 4 12 mm
What it should look like.
See them 4 12mm? Take them off after you drain all the oil. Some more will come when u pull them 4 bolts. So grab a rag.
With the 4 bolts off it will be stuck om still. Grab a hammer and tap the back of it off. If you dont like to get your hands super greasy, Take off your nice clothes and buy some fast orange from harbor freight and deal with it
This is the disengaged postion, You want to slide it to the left, But not to far.
This is too far to the left. It can get stuck their sometimes and youll have to use a flat tip . you want it to just cover those teeth.
Since im just a 15 year old, I forgot to take a pic of the slider in place inside the axile tube, but if you read all my captions you will figure it out. Slide the fork all the way to the side with the wire clip and then put a clamp on that tube. This part can be a PITA sometimes so make sure you have patience and a good clamp. It took me an hour because it can be hard to get that clamp back together . because you have to pull the clamp apart to get the clamp on the tube.
Afterwards put all the bolts back in after you line the fork up and stuff. Use some of the old vaccum lines and plug the 2 ports on the ADD System into each other for extra precaution and to keep crap out of them.
This is a shot off my truck of the add system. I got rid of the wires and this pic also shows you how to plug the lines into each other just incase you need it.
These are your vsvs. Pull them off and junk em, you dont need them anymore.
See these old lines? Pull them off and do what you want with them. I keep them since they $$.
See that ugly thing inside your wheel well? Take it off and junk it.
See the line in my hand? Take it off.
Thats what i did on my truck with the open port from the old hose in the last pic.
Their you have it. I don't have the best grammar because i am only 15. I love T100s and theirs nothing on these trucks i haven't done. Ill post a new forum tomorrow in the T100 section. Hope this helps other people. Works great and feels amazing im 4x4 for me anyway.

swampedout

thanks for the write up and the pictures, its very helpful to see whats going on in there. how does your truck ride in 2w when you've taken the ADD out? 99% of my driving is on pavement and I like the idea of taking all this vacuum stuff out but I dont want to make my street driving any worse.

Tilikum102602

ADD Does not work once you take it out. It keeps the differential activated. Its like a solid axile kinda. And you only have 4x4 when the driveshaft gives power to it. All it does is allow 4x4 to always work

iLikeT100

atcfixer

iTrader: (1)

I'd suggest the manual locking hubs too. Besides better mpg, your CV axles will see a lot less wear. Less spinning mass, so take offs will be slightly faster and the steering might be a tiny bit lighter feeling. Say it's winter time, chance of snow, lock in the manual hubs before you go, if you need 4x4 on the trip, just pull the transfer case into 4x4. If there's basically 0 chance you need 4x4, leave them unlocked.

I'm also dealing with an actuator that's acting up. Cold it works fine, after a trip or summer time it doesn't like to lock in. VSV valves test fine in my case. My plan was to put vacuum to the actuator all the time to keep it locked in and run manual hubs.

FYI, with an ADD system, the CV axles are always spinning even with a correctly working OEM system, the ADD system disconnects the axles from the input shaft. Old school hubs disconnects it at the wheel hubs.

Tominlaw

2 questions, which one did you replace and where did you find it so cheap?