1999 transfer case won't engage

[martyj96]

Hello,
I just bought my 15 year old son a 99 4runner. The transfer case won't engage. The light doesn't come one either. I checked the 4wd fuse and it is good. Is there somewhere I should start that may be the most likely cause? Thanks

 

[TheDurk]

Hello,
I just bought my 15 year old son a 99 4runner. The transfer case won't engage. The light doesn't come one either. I checked the 4wd fuse and it is good. Is there somewhere I should start that may be the most likely cause? Thanks

How did you determine that the problem is in the T-case and not the front diff. (much more common)? Auto/manual? J-shift or push-button?

 

[martyj96]

I don't , it could be the front dif, it is auto with multi mode. Thanks

 

[TheDurk]

Well, that's the first thing to figure out. I'm not familiar with the multi-mode, but I think this should work:

First, verify front shaft turns by hand in 2wd. With key on, engine NOT running, engage 4HI. If shaft locks, T-case is good, ADD system is bad. If shaft still turns problem is in T-Case. (The ADD--Automatic Disconnecting Differential--runs on vacuum so it will not engage with engine not running, but the T-Case on the multimode is electric, so it should engage with just the key on.

If the ADD is the problem, here is how to troubleshoot (from an earlier post of mine):

Don't guess at it, troubleshoot! Start at the twin VSV's (Vacuum Switching Valves) on the driver fender wall. There are two long vacuum hoses that come up from the diff, one goes to each VSV. Check to see that one of the two hose nipples on the VSV’s has vacuum (engine running, 4WD NOT engaged). If no vacuum either side, check the check valve going to the intake manifold and look for loose hoses or a hole in the reservoir. If there is vacuum going to one hose, then put it in 4WD. See if the vacuum switches to the other hose. If it does, and no 4WD, problem is the diff actuator or the line to the diff. If it does not, then just switch the hoses and you should go into 4WD. This confirms diff is okay. (Mark the hoses first so you know which belongs where!)

OK, switch them back. Then use a test light to see if electrical signal from the TC also switches sides of the VSV. If it does not, problem is the TC, the switch on the TC, or the TC actuator, or its wiring back to the button (last two for non-J shift only). If it does, but the vacuum does not, the problem is the VSV itself.

I start troubleshooting at the VSV's because you can figure out where the trouble is without having to climb under the truck. [Does not apply to '01-'02]

If the multi-mode T-Case is the problem, somebody else needs to help. I don't do slushboxes.

 

[martyj96]

Thank you, That helps a lot.

 

[freightdogfreddy]

Damm Durk, I could use a lil help here lol. My transfer case wont engage, 1997 limited with the push button switch. Front driveshaft out of the transfer case spins, 4wd button pushed on or off. I checked the switch on the 4wd/hi/lo lever, it has power, I bypassed it, still nothing. Switching the vacuum lines on the VSV's locks up the front differential, so that's working good. Engaging the RR diff lock switch, it flashes red on and off on the dash annuciator, I don't know if this is normal or not. One thing is for sure, that transfer case actuator/motor is A) not getting power, or B) frozen up. Is it possible to change this motor without removing the transfer case? I'm also looking for the 4wd ECU I can't seem to locate it, it's not under the pass kick panel. Any help is appreciated