4WD Not Working...

Hey everyone. New to the forums and having some issues with the 4WD. 2002 Tacoma auto 3.4. When I push the button absolutely nothing happens...no light, no noises, just nothing. I just bought the truck so I am not sure of the last time it was working. The weird part is once in a while when I turn the truck on the 4WD light will be on and will not turn off until I turn the truck off. Also when I am driving on the highway and click the 4WD button the light will come on but will not engage. The light will not turn off until I turn the truck off. Any input would be great. Thanks

 

anyone?

 

Probably the motor on the diff that activates 4wd...do a j shift swap.

 

Do you have any info on that? thanks

 

Just fyi i wouldnt try and engage 4wd while at hyw speeds.

Ive always had manual hubs with the j shift transfer case so no experience with your particular setup. But as mentioned by Anthony, id guess that stupid lil motor went tits up on ya too...

Have u tried engaging 4wd hi and low and then doing it while rolling in reverse and back and fourth? Might be worth a try if not??....

 

Yeah I have tried just about everything just to see if I could get a reaction out of it but nothing. Could it be electrical possibly?... You know that part number for that motor on the diff?

 

I don't know the part number. J shift t case is nice because no electrical button like you have...you shift it in and it goes in

 

Might just be a blown fuse

 

If its a bad actuator (on the front differential) the part number is 41400-34013 (around $300).
Don't replace it unless you confirm thats is the issue. Eliminate electrical problems first.

Get a service manual (Haynes is better than nothing), and start troubleshooting.
If that is beyond your capability, take it to a shop for a diagnosis.

 

Yeah check the 4wd fuses

 

I only have experience with the 2nd gen system, so you may have to modify this info for the 1st gen. The system has two actuators driven by small motors, one to engage the front differential and one to shift the transfer case. Both are very easy to remove. If the other suggestions don't pan out, I would remove the actuators and open the covers. Inside you will find a motor and few small gears. If you connect pin 1 and pin 2 (check the correct pins for the 1st gen) to 12 volt power you can drive the motors. If the motors work, then it's some other electrical problem (maybe the 4wd ECU is confused). If one of them doesn't work, then you know what the problem is. Sometimes the problem with the actuator is just a bad solder joint on the motor terminals. Check that all the internal wires of the actuator and attached correctly.

Hope some of this helps. It's a pretty simple system once you really start looking at it. But, as with anything electronic, it can be tough to find the cause of a problem.

 

First things first.
The 4wd fuse is in the cab fuse box near the driver's knee. Pop off the little cover and you should see 9 fuses. On my '99, the 20-amp 4wd fuse is the upper left one. Remove and check.

If you have a 2-4 selector switch, as well as the ADD switch, then the electrical stuff is more complicated. What do you have?

 

Thanks for the replies. I'm going on get started on diagnosing this thing later tonight. If I can't find the problem then I'll make an appointment at the dealership. I will post once I figure out the problem.

 

Welcome to TW, since you have electrical engagement you need to start here, & I've found that issues with either Elocker (locking rear diff on TRD models) or 4wd engagement w/ADD hubs is usually a lack of use or engagement on a regular basis, not being a mechanical engagement (T-case lever) this is huge factor meaning ya gotta "Use it or lose it", & I'll add that DO NOT get into the habit of engaging 4wd on pavement or at speed...start looking for blown fuses/bad connections/etc;

 

Something else I thought of... it does grind when I switch the t case into 4lo or hi from neutral. I'm not sure if that is normal?

 

Are you stopped with the transmission in park/neutral?

 

Yeah complete stop transmission in neutral

 

Yeah it's gonna be a bigger problem then just a fuse

 

Yeah all fuses are fine

 

Grinding def. not normal, could be a dirty gummed up acuator/solenoid, bad connection /low voltage making it "hang" or a failing/failed actuator...