2002 4Runner nothing works in the back/rear tailgate FIXED!

Hello everyone I'm new to this forum.

My 4Runner have over 250k miles and nothing works in the tailgate.
Defrost, rear wiper, rear window, washer does not work.

Things the I already checked.
- Wires by the tailgate looks good, I even tested all the wires from one side of connector to other side (ecu side) of connector, and all the wires have continuity.
- There is ground at the ecu
- There is 12v constant power at the ecu
- There is 12v ignition power at the ecu
- checked the window switch it sends 12v when rolling down.
- Window motor works by apply 12v.
- Checked fuses all good
- No, window lock is not on

I don't know what else to check, the only thing left is replacing the tailgate ecu.

When I press the button to roll the rear window down the switch sends 12v, however it does not get 12v at the tailgate ecu. If the signal wire is broken then how come the other stuff doesn't work.

 

FYI, ECU stands for Engine Control Unit. I think you're actually talking about the tailgate unit. There is no engine in the tailgate

So what I think you are saying is that you tested the wires at the internal unit in the tailgate and not all the way to the ECU which is at the front of the car.

If so, you probably have a break in the wiring between the top of the rear hatch and the top of the body. This is very common. Those wires flex and break eventually. You need to test all of those wires across the junction from the body to the tailgate.

If I misunderstand, let me know.

https://www.youtube.com/watch?v=fhnQzx2BTUo

 

ECU also stands for electronic control unit, and it's literally called back door ECU in the owners manual.

I know it's very common for those wires to break, like I mentioned I have checked those wires and also test each one of them from the headliner side to ecu side which is connected to back door ECU

 

Apologies, I've always heard of it in regards to the engine.

If that is the case, it does sound like a bad Back Door "ECU".

If you can, unplug all the devices and then see if one by one, you can get anything to start working through the Back Door ECU. Maybe one of the devices like the defroster\buzzer\switch\motor or something is causing an issue?

 

I powered the back window motor directly and it works (goes up and down). I believe everything is working and the wires are good because the ecu have 12v constant and ignition etc...
The swtich works the motor works, it looks like it's not getting power signal from the switch to the back door ECU or the ECU is not sending signal.

I'm gonna replace the ECU, because I can't find anything else. I wish it was just a broken wire.

 

Replaced the back door/window ECU/relay box unit now everything works

 

Where did you get your new ECU? Is the only option an OEM Toyota?

 

$60 from Junkyard/Facebook marketplace
Check local junkyards https://www.car-part.com
Or ebay.

The guy said there are few units with different part numbers, and he gave me the one with matching part numbers. I don't know a different part number will work or not.

 

Thanks for the tips. My 2000 had some damaged wires where the wire bundle goes into the roof from the lift gate. I repaired them and regained the use of my dome light in the on when open setting. But the tail gate still gets stuck when it locks and does not unlock. I already replaced the latch assembly so that was not it. It is becoming more likely it is the tail gate ECU.

 

Before replacing the back door ECU, first check the back door lock/unlock motor and switch if you haven't checked already.

I would also double check all the wires in the boot on lift gate.