Flashing 4WD indicator light

[Esolly84]

Power is only sent to the rear driveshaft in 2wd. 4HI the transfer case sends power to both driveshafts but they can spin at different speeds. 4HI Locked and 4LO the transfer case sends power to both driveshafts and locks them together like a traditional transfer case forcing them to spin at the same speed.

Thanks for clearing that up! Also just tried turning the front driveshaft with the rear tires on the ground in park. Could not spin the front driveshaft, it was getting bound up by the rear wheels on the ground

 

[phattyduck]

This is my first yota with a multimodal transfer case so I’m trying to get a grasp of how it works. From what I’ve read online and in this thread it sounds like the transfer case is always sending power to both shafts. Clicking it in to “4wd” is “awd” and this is done by the Actuator on the front diff, then the center diff lock can be used for a true 4wd. Is that right?

No. In 2WD, the front differential is disengaged (well, the right output is disconnected) and the transfer case only sends power to the rear wheels.

In "AWD" mode (4hi unlocked), there is a differential that acts exactly the same as one would on either axle (packaged differently, but same end result). If the transfer case is in this mode and the front differential is disconnected, the truck isn't going anywhere - it would be the same as lifting a tire in 2WD.

I don't know the specific order of operations to go from 2WD to 'AWD' but it happens - and it involves both the front diff actuator (vacuum on '99/'00 and electric on '01/'02) and the transfer case actuator.

-Charlie

 

[Bad Luck]

Thanks for clearing that up! Also just tried turning the front driveshaft with the rear tires on the ground in park. Could not spin the front driveshaft, it was getting bound up by the rear wheels on the ground

That indicates that the transfer case isn't in 2wd then. I would try applying power and ground directly to the transfer case actuator to see if you can get it in 2wd. The two larger wires control the transfer case actuator. Disconnect the wiring harness from the transfer case actuator, apply power and ground to the two larger terminals, and you should hear the actuator moving. You might have to switch your power and ground in order to find the 2wd setting. You can check for 2wd by trying to turn your front driveshaft again with the front wheels off the ground and the rear wheels on the ground. the front driveshaft will spin freely from the rear driveshaft when in 2wd.

I'm starting to suspect the transfer case actuator or the timing of that actuator if the previous owner replaced it. Most people replace the transfer case rather than try to replace the actuator and time it. There's not much information on timing the actuator.

 

[96RedRunner]

To find out what you have going on look at FSM section TR-48 thru TR-53 and go from there.
[MENTION=319302]Bad Luck[/MENTION] point of timing being off sounds about right.
Haven't had problems with mine yet but it's the route I'd take.

 

[Esolly84]

That indicates that the transfer case isn't in 2wd then. I would try applying power and ground directly to the transfer case actuator to see if you can get it in 2wd. The two larger wires control the transfer case actuator. Disconnect the wiring harness from the transfer case actuator, apply power and ground to the two larger terminals, and you should hear the actuator moving. You might have to switch your power and ground in order to find the 2wd setting. You can check for 2wd by trying to turn your front driveshaft again with the front wheels off the ground and the rear wheels on the ground. the front driveshaft will spin freely from the rear driveshaft when in 2wd.

I'm starting to suspect the transfer case actuator or the timing of that actuator if the previous owner replaced it. Most people replace the transfer case rather than try to replace the actuator and time it. There's not much information on timing the actuator.

Just tried this and go not movement in the actuator or transfer case. Waited a while and plugged the harness back in and tried to cycle the 4wd button while going forward/reverse. Nothing happened but the actuator got quite hot. I’m guessing that its a bad actuator… found a decent write up on yotatech on replacing the actuator, but not sure if it’s worth going that route if you’re saying it can’t be set right.