Toyota Tundra Forum

When I press the 4 HI button, the green light just flashes. It is not going into 4x4 mode. Any ideas?

Have you tried the truck in neutral while not moving? If that still doesn't work, and I'm certainly no 4 WD expert, but it sounds like a bad solenoid/actuator to me.

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2007 Tundra Limited Double Cab 4x4 Super White
Volant CAI
Pioneer AVIC Z-2 (hard drive upgrade to AVIC Z-3)
Key FOB Tailgate Lock (courtesy of Toxarch)
OEM back-up camera w/flip down monitor microswitch mod
Sirius Satellite Radio
WeatherTech Floor Liners
20" OEM alloy wheels
Line-X Bed liner
UWS Black Powdercoat Low Profile Toolbox
DU-HA underseat storage unit
JC Whitney Black Nerf Bars
Lund Interceptor II Bug Shield
Tekonsha Voyager Brake Controller

I tried in park, but same result. Will try in neutral.

Solenoid is my initial guess as well. But like you, I'm not a 4wd expert.

Couple of other things I thought you might try if you haven't already.... try engaging the 4WD while moving slowly forward. If that doesn't work, try engaging the 4WD while in park or neutral and while light is flashing, move forward or backward slightly.

Looks like it is one of 2 things per the manual. 4WD Control ECU or the actuator (or its solenoid). Now, how do I figure out which? Is there a fluid sensor that plays into it? I recently changed all the case fluids, so maybe one is leaking(?).

Now I find that there is also an actuator and ADD (?) on the front diff. This is a bigger lot to troubleshoot than I thought.

Did some hands-on troubleshooting. The transfer case actuator is engaging for sure. The ADD appears to do nothing. Wondering if the 4WD sensor needs to activate before the ADD does. If so, the sensor is probably bad. If not, then the ADD actuator is bad.

Anyone know for sure? I plan to pull the sensor and test it later this weekend.

Just joined this site because I'm having the exact same issue with my 04 tundra's 4x4 not engaging. I will likely send mine in for repairs though since it's still covered. I only bought mine last fall with warranty....thank goodness!

You guys please keep us posted as to what was found to be the problem. Might help some other GEN 1 4WD members in the future.

I took mine in to Toyota since it was under warranty. They said the problem is the ADD actuator that engages the front axel. Not the transfer case actuator. Which is good for them since the ADD actuator is only $600.00 CDN vs $1500.00 for the other. For Zonker17's case I hope it is the same componant because you might be able to find a refurbished one for even less money.

Danny