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Bypassing Vac system

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22 Nov 2025 10:12 #262885 by Sken
Bypassing Vac system was created by Sken
Hello ☺️

First post here, if i have posted in the wrong section please move it or if someone could point me in the right direction i would greatly appreciate it.

So, bought (unwittingly) a 2007 gen 3 with a whole host of problems, however rather than sending the vehicle to the great scrapyard in the sky i am saving her. 

Slowly getting jobs done but have got to the 4wd system. Green 4h light constant flashing, buttons dont seem do anything. Rather than invest a small fortune replacing the vac system i intend on instaling manual hubs. A while ago i found some info on bridging/joining two wires to fool the system but cant seem to find it now. 

Any help please? 

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22 Nov 2025 11:21 #262886 by facade
Replied by facade on topic Bypassing Vac system
If you look underneath the battery there are a side by side pair of electrically controlled valves with a nest of rubber pipes that control the hubs.
There is also a round switch attached to one pipe.

Join the wires that go to the switch.

The 4WD controller will think that the hubs are working. (Strictly it will think that there is no vacuum leak and assume that the hubs engaged)

If it suddenly breaks, go back to the last thing that you did before it broke and start looking there :)
The following user(s) said Thank You: Filipao, Sken

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22 Nov 2025 16:51 #262888 by Busta
Replied by Busta on topic Bypassing Vac system
Replacing the whole vacuum system with new PVC hoses costs about £15 and is a quick and easy job to do. But before you do anything you need to make sure you're fixing the correct part. Do as Facade says, bridging the wires in the white plug. If this fixes it then replace the hoses. If you still have issues with the plug bridged there's a very good chance it's a problem with the transfer case, typically the actuator. So check this is working before you spend any money.
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23 Nov 2025 09:12 #262889 by DrRobin
Replied by DrRobin on topic Bypassing Vac system
Good for you saving another Jimny. They are fun cars and fairly easy to work on.

The BigJimny Wiki should be your friend if you haven’t found it already, it has articles on fixing most things, see here for the 4WD system.

www.bigjimny.com/mediawiki/index.php/4WD..._failure_diagnostics

Remember to post a few pictures of your Jimny and the jobs you have done and good luck with the rebuild.

Robin

2020 blue SZ5 (one of the last to be registered in the UK)
Ex 2011 Blue Jimny SZ4
Northumberland Jimny Blog

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23 Nov 2025 11:58 #262890 by Sken
Replied by Sken on topic Bypassing Vac system
Thank you so much! That was exactly what i was looking for!

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23 Nov 2025 12:05 #262891 by Sken
Replied by Sken on topic Bypassing Vac system
Thanks for the link to the BigJimny wiki, im sure will come in very handy.

So far ive done tyres (cheap AT'S for the time being) replaced discs, pads, shoes ect, new kingpin bearings and a steering damper.

New vitmods shocks and 2" springs, replaced Cat and backbox. Fitted the snorkel too.

Next job is manual hubs then off to the fabricators for welding. Once thats sorted its gearbox (and clutch, props ect) time

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