Is the 4x4 controlled by the ECM?

Hi everyone,

Thank you all so much for sharing all of your knowledge. This is an incredible resource.

I recently bought a 1999 Tacoma with the V6, and 100,000 miles on it. This baby is in great shape.

But during our ice storm this week in Portland, the 4x4 quit working. The transfer case engages, but the front differential does not engage.

My driveway is a slush puddle, so I took it to a shop recommended on here. They are telling me that it is a computer problem that won't allow it to shift into 4 wheel drive.

Does this sound reasonable to you all?

Are there issues with swapping in a junk yard computer, or is it a plug and play kind of project?

Thank you all for any help,'
Mike

 

What kind of transfer case do you have, the push button or the j-shift?

 

It is the J shift

 

Perfect so there isn't very much to this system, it sounds like your ADD isn't engaging or, possibly the switch that tells it that it has engaged is malfunctioning.

If you lean your head into the drivers side wheel well do you see a vacuum can in there? Looks like this...

 

How often prior to this problem had you used the 4wd and it worked fine?

While my 2000 does see some signals from the ECM I think you would have far more problems then just the ADD system. They may have meant the 4wd ecu .

Failed vacuum hoses or a vacuum switching valve or a stuck actuator on the front axle would be my guess.

Best of luck