Another Mystery Plug... er Mystery

[stuzbot]

I came across this one today, while doing an oil change. It's spliced into the wiring for the brake fluid level sensor on the reservoir. But what is it for? I couldn't see anything nearby that it could connect to.

1st pic is where it was when I found it. 2nd pic is when I lifted it round the reservoir to see where it joined up

 

[Beastrider]

Hi - it’s the connector for the brake vacuum warning switch - see photo of mine. I believe this switch is only fitted to diesel models.

 

[Lancashire Cruiser]

I have this same plug on my 3.0L diesel but looks like it’s never been plugged into anything.

 

[stuzbot]

I've not had another look again yet, what with closing my bonnet afterwards being such a palaver. But I don't think there was anything nearby for mine to connect to either. Because I did look round to see where it might have become disconnected from.

 

[Beastrider]

Strange that my 3L diesel should have the switch but not yours. Maybe it was phased in (or out) during the production run...? Mine is November 1999. The Max Ellery manual clearly shows the switch in their photo and wiring diagram (as per my photo) but the Haynes manual does not show it fitted - the vacuum booster is just blank in that area in their photo. Curious! Anyway, that connector is for the brake vacuum warning switch.

 

[Lancashire Cruiser]

Mine is a 97. Could it have been an optional extra on earlier versions and standard on later?

 

[Beastrider]

I really don’t know. I doubt it was an optional extra but it could have been a change in safety legislation, maybe. For a diesel, there is no vacuum generated by the engine so the vacuum is provided to the brake booster by a separate pump. Perhaps they had to add a switch to warn the driver of a vacuum failure? But then why have the wiring installed and not the switch? Perhaps the switch was compulsory in some markets and not others. In the end, it may have been cheaper or more convenient to have all the boosters with switches rather than some with, some without?