I have a malfunctioning transfer case on my '01 Toyota Sequoia. It has 65k on it, but the 4WD has been used sparingly. The 4WD won't engage on the fly, but only when stopped. The dealer says it could be the Transfer case Control unit, or the Transfer Case itself. There is a very big difference in the parts cost. $330 vs $4000.
My question: how hard is it to replace the transfer case assembly? Is it just remove & replace or is there more to it? Also, how hard is it to replace the control unit and where is it located?
I have lots of auto experience, but have never worked on 4wd before.
Automatic disconnecting differential actuator, ADD allows for engagement of 4X4 on the go, a flange is mounted on the front hub which is splined onto the axle shaft connected to a side gear shaft on front differential. Locking hubs are not used with ADD.
When the transfer case is shifted into 4wd, ADD is shifted into 4wd by operation of ADD actuator electric motor. ADD actuator engages clutch sleeve intermiediate shaft in front diff. and side gear shaft providing 4wd operation. When vehicle is in 4wd an indicator light on the dash is lit.
Operation of the transfer indicator switch or 4wd switch completes the ground circuit which allows the ADD relay to operate, when the relay operates, voltage is supplied to add actoator! If it was me I would chech these switches and relay first!