Hilux 4wd not Engaging

[MATT009]

Hi. I have a 03 hilux sr5 1kz engine manual g-box. The 4wd wont engage. It has the hi/lo ratio selection lever and the 4wd push button on the side. Front diff is ADD and transfer also has an actuator to engage the front driveshaft refered to as ADD also i assume.
I have searched for hours on the net for diagrams and the same issues etc but i can only find stuff on surfs not on the hilux.
So far i have worked out that the front diff actuator is fine by switching the VSV's around and testing the sensor switch and also jacking up spinning wheels. Both VSV's work fine and there are no vacuum leaks.
When i push the 4wd button the Relay/4wd ECU is clicking but the transfer actuator is not working and neither is the 4wd VSV or the dash light.

I have put power direct to the transfer actuator terminals and it doesnt seem to do anything.
What i want to know before i pull it to bits any more is how to remove the transfer actuator and what is the best way to test it to see if it is stuffed im hoping it just needs a clean out but i dont want to pull it off before i know what to expect.
Also i am after a diagram of the system so i can confirm i am looking at it the right way.


thanks

[tallsam66]

There is a plug on the diff , its connected to a switch that registers when ADD is engaged.If ECU doesnt get signal ADD is engaged transfer case wont engage.
Check the cabling is intact.

[madlux]

On the transfer case there should be a three bolt flange with a vac line going into it. Remove three bolts, clean the contacts behind. Make sure the o ring around the flange is doing its job and sealing. If not use sealant. Make sure the vac hose going into flange isn't split also.

[MATT009]

There is a plug on the diff , its connected to a switch that registers when ADD is engaged.If ECU doesnt get signal ADD is engaged transfer case wont engage.
Check the cabling is intact.

Doesnt the transfer engage first and then this tells the diff to engage? I understand on the surfs it works different.

[MATT009]

On the transfer case there should be a three bolt flange with a vac line going into it. Remove three bolts, clean the contacts behind. Make sure the o ring around the flange is doing its job and sealing. If not use sealant. Make sure the vac hose going into flange isn't split also.

Do you mean on the actuator? I took the 4 bolt plate off on the passenger side and oil started coming out so i quckly chuked it back on also same with the sensor. I see the drivers side has a vacuum hose i will try that side. Maybe i will take some photos tomorrow so we know we are talking about the right transfer set up.

[tallsam66]

There is a plug on the diff , its connected to a switch that registers when ADD is engaged.If ECU doesnt get signal ADD is engaged transfer case wont engage.
Check the cabling is intact.

Doesnt the transfer engage first and then this tells the diff to engage? I understand on the surfs it works different.

Hilux may be different but surf engages ADD then xfer case... if ADD not engaged transfer wont engage.

[MATT009]

There is a plug on the diff , its connected to a switch that registers when ADD is engaged.If ECU doesnt get signal ADD is engaged transfer case wont engage.
Check the cabling is intact.

Doesnt the transfer engage first and then this tells the diff to engage? I understand on the surfs it works different.

Hilux may be different but surf engages ADD then xfer case... if ADD not engaged transfer wont engage.

Yeah pretty sure the hilux is different to the surf for some reason. From what i can gather anyway.
Really after a diagram of the system and also how to remove the transfer motor i know the obvious undo the 3 bolts and 2 plugs but what to expect when i remove the actual unit. How does the shaft of the electric motor connect to the 4wd selector.

[MATT009]

Still not resolved... surely theres someone on here that knows about these things! Might have to pay toymota dealership a visit.

[Mehrts]

I have a schematic diagram for the entire ADD system but I can't attach it due to being too large. Shrinking it makes it unreadable..

Might take a bit to understand if you haven't dealt with electrical systems before.

[marmite89]

hey mate did get your 4wd to engage?

[Andygoodbloke]

May have to visit some one with a diagnostic computer, then look up the fault code and clear all faults in ECU, like everything these days the bloody computer maybe saying no. Good luck