No 4wd, need help with troubleshooting

You can PM me directly, and I'll post the resolution here.

You checked ALL the info I listed? For voltage and continuity? You pull the the center bezel to inspect the 4wd ECU?

As you can see in the EWD I listed, both ADD and transfer case actuators are powered by the 4wd ecu under the stereo and it receives it's power by the 20A 4WD fuse. The 4wd ecu needs to be tested to rule it out. If you're not receiving voltage to either of the actuator harnesses continue to rule out the weak link in the circuit. Check continuity in the 4wd ecu ground on the harness and frame ground, check pin 12 on the 4wd ecu harness for 12V.

We'll try to get your 4x4 working.

 

I have a known working 4wd ECU BTW, if that's seeming to be the issue...

 

Ah ok. I thought it was for everything, any suggestions?

 

When i was converting to AWD, the ADD motor i had was bad. totally locked. during that time, the 4WD lights just kept flashing.
(my 4wd ECU is from a 4Runner Multi but it should work the same)
if you hear relays working, can u also check if the light is working in the instrument panel? just to rule out that the light is busted or not.

i assume that both Transfercase and ADD motor you have tested and they are ok?
so that means its down to checking the wiring one by one. its easy but tedious... just follow the manual provided above.
you should also try to acquire the complete EWD manual for your year model tacoma from TIS if you can.
it takes the guess work out if you do and will provide correct color wires so you can trace.

CK

 

The FSM doesn't have an accurate description on how to test the TC actuator. The plug is incorrect and it states to test 6 pins when the actual plug only has 5.

And all available testing methods have been discussed with the OP. And he's solely responsible for attempting to take the steps necessary to diagnose the 4wd circuit. That's where the communication was left at.

 

ok Thanks for the update. mine had 6pins but its a VF3AM TC.
but from what various Tacoma EWD i had, 6 pins seems to be the norm for TC motors. so he might be missing one pin.

 

Well I'm gonna check each wire for continuity tonight....wish me luck

 

Ok I just checked all the wires and every single one has continuity, the transfer case plug and add plug up to the 4wd ecu.

 

I doubt he's missing a pin, I know it has 5 pins because I have a full 2-4/auto tranny/engine harness in my shop and it has 5 pins and it also came from a truck w/o any 4wd issues. The TC actuator plug is completely different in the FSM.

And you did the testing procedures on the ADD actuator?

 

Not sure what all you tested, but from the little undescriptive info I got from you.

• You've tried 2 4WD Ecu's
• 20A 4WD fuse
• Continuity from 4wd ecu to each actuator plug(all continuous)
• 12v across each leg of the 20A fuse and body ground
• Tested 4WD Position Sensor

That leaves the actuators.

 

Ok guys I think I have it figured out, since I got continuity on ALL 4wd wires, I thought maybe it was in the connector and maybe the pins from the 4wd ecu. So I bent all the pins on the back of the computer slightly up so that they make better contact with the plugs and it's been working all weekend. Thanks for the help with troubleshooting!

 

Glad you got it sorted. Happy to hear $$$ wasn't throw at it too much. Thanks for posting the resolution here. May very well help someone in the future.

 

1st gen no light will come on if the ADD is not engaged. It's how the wiring is run