I've got a 2000 SR5, 4.7, 4WD. Recently when I select 4WD, nothing happens.

The Light doesn't flash. There is no sound coming from the Transfer case. The fuses are good and power is getting to the Center integration panel and the 4WD ECU. The pin on the cable going to the ECU seems to change state when the button is pushed. I'm thinking the ECU is bad. Any Ideas?

 

Have you checked the actuator at the transfer case?

 

Yes it works when I bypass the ECU. Haven't tried the front Actuator yet.

 

When was the last time it was used?

 

I'm going to ask the stupid question because you never know until you ask.

You're hitting the 4HI button, right?
Nothing flashes when you press the button?

 

FWIW.

The FSM suggests moving the truck back and forth...if you get no 4x4 light after pushing the button.


Roy

 

Right, I'm pushing the 4 Hi button. I've narrowed it down to the ECU. I'm Getting the input to the ECU when I push the button, but no output.

 

Water intrusion at the ECU?

 

Do you have the 4x4 ecu pin specs?

 

I don't think so.

 

I do have the pin-out for the ECU.

 

In case someone needs them.

 

Replaced the ECU and I have 4WD again.

 

Great to hear! Any obvious reason for failure?

 

And, did you buy new, used, or what?

 

No obvious cause. Nothing visible on the circuit board. It was new. I didn't even think of trying to find used, probably should have tried. I paid $357 for it at Toyotapartsdeal.com.

 

$357 well spent if the 4wd works again.

 

Welp, won't be replacing that for another 20 years.

Good solve, OP

 

Thanks for the wrap-up.

There are a bunch of things I like about my Tundra...none of those things are connected to the 4x4 control system.

Roy