4WD Problem: update

[MudSurfer]

I've swapped the 4WD ECU from the 2 doors, and it still doesn't work - maybe it's a different one, but I doubt it......

Any suggestions now??

[The Lang-Shankit Scunner]

I've swapped the 4WD ECU from the 2 doors, and it still doesn't work - maybe it's a different one, but I doubt it......

Any suggestions now??

Landcruiser?

[Apache]

I've swapped the 4WD ECU from the 2 doors, and it still doesn't work - maybe it's a different one, but I doubt it......

Any suggestions now??

Does it malfunction in the same way?

Try what I suggested, it could still be a duff sensor.

[MudSurfer]

Does it malfunction in the same way?

Try what I suggested, it could still be a duff sensor.

Yep - does exactly the same thing - the relay clicks on and off so fast I thought my indicators were on.....

[MudSurfer]

You say the relay clicks in and out, which suggests that the ECU is engaging and disengaging 4WD repeatedly.

Now, its either doing this because it's getting the wrong signals from the ECU, OR because the ECU is getting the wrong signals from its sensors (ie, road speed too high).

Removing the actuation signal from the relay (the coil connection, you'll need to check whether it's active high or low with a DVM) and substituting it with a known voltage of the correct value should mean you can actuate 4WD without ECU 'consent' if you like.

If 4WD works like this, then the ECU is probably at fault, as there are no mechanical problems stopping 4WD working. If it doesn't work, then the ECU was probably receiving 'no go' signals which relate to a problem with the mechanical side of the 4WD system.

Either way, it should narrow it down.

Sorry Andy - could you explain how to do this?? I get the concept, just no idea how to do it.....

[Apache]

Find the 4WD relay again, the one you hear clicking on and off.

There will be a wire which connects to the coil of the relay to activate it (the relay will probably be marked to indicate where the coil connections are). It will more than likely be '12v active high'. In other words, 12v is applied to it by the ECU in order to start the process of engaging the 4WD system.

Disconnect this wire temporarily.

You could then check to make sure it doesn't click and doesn't even attempt to go into 4WD.

Then, take a 12v feed from anywhere, and connect it, via a temporary switch (anything will do) to where you disconnected the other wire.

Start the car, and then apply the 12v via the switch. See if you get 4WD.

We appear to have ruled out the ECU itself, but 'forcing' this relay to operate will tell you if there is a mechanical problem with 4WD. If you dont get 4WD (or hear odd / horrible noises) then you have a mechanical problem.

If on the other hand, you DO get 4WD, there is a sensor problem giving the ECU duff info and preventing you getting 4WD.

If you're gonna have a go tonight, give me a bell (after 6) and I'll try to talk you through it.

Are there any diagrams around of the ECU, its inputs and outputs?

[BUSHWHACKER]

Any help?.....




Sounds like the actuator collar is sticking to me, the part that slides across to engage the front driveshafts.
The front wheels must be turning in order for it to engage BTW.

[Apache]

Vince, thats a possibility.

I would also check the transfer case sensors. Ideally, I'd need the truck in front of me. It does look very simple though, and should be easy to :-

a) Check the sensor outputs
b) Disconnect them and spoof the ECU into believing everything is OK

Mudsurfer, if you get no joy in the next couple of weeks, let me know and arrange to pop over with it.

[MudSurfer]

Vince, thats a possibility.

I would also check the transfer case sensors. Ideally, I'd need the truck in front of me. It does look very simple though, and should be easy to :-

a) Check the sensor outputs
b) Disconnect them and spoof the ECU into believing everything is OK

Mudsurfer, if you get no joy in the next couple of weeks, let me know and arrange to pop over with it.

We are away this weekend, but free the next one - did you want to come down here for the day??

[Apache]

Would be better here as I may be looking after the kids. I'm off for a few days after easter. I'll find out when and let you know.

[MudSurfer]

Would be better here as I may be looking after the kids. I'm off for a few days after easter. I'll find out when and let you know.

Thanks mate - I'm minutes away from reaching for the matches......

[sledge]

Thanks mate - I'm minutes away from reaching for the matches......

noooooooo don't do it lol

[Apache]

Thanks mate - I'm minutes away from reaching for the matches......

I'm off work 31st March to 2nd April inclusive. Might be able to have a look one of those days...

[MudSurfer]

I'm off work 31st March to 2nd April inclusive. Might be able to have a look one of those days...

I'll see if I can get the 31st off and come up early so the diff etc has time to cool down if we end up stripping it to get to the sleeve....and grease it all up.....

[Apache]

I'll see if I can get the 31st off and come up early so the diff etc has time to cool down if we end up stripping it to get to the sleeve....and grease it all up.....

I'm reckoning on a duff transfer box sensor at about 5:1 favorite at the mo...