Can ignorance really be bliss?

[Mr Bean]

I removed my 2.1 WBX to fix a stripped exhaust stud thread and change the water pump expecting find one or more problems etc. And sure enough...
After unearthing some previous dodgy bodging and doing some proper bodging I noticed what appeared to be a pressure sensor near the oil cooler from which I had not removed a connector when I removed the engine. The connector tag being either accidentally or deliberately bent over. Reference to my Bentleys revealed that there are two oil pressure switches - a low pressure switch which operates the oil pressure warning light on the dash and a higher pressure switch down near the oil cooler which I believe to be the Audible alarm.
The engine was rebuilt about ten years ago and clearly this second - high pressure switch has not been connected at least since then.
I clearly have the oil pressure warning light in the dash working but presumably not the audible alarm.

Does anyone know the colour of that wire and where I could find it lurking in the loom just in case I decide to restore that functionality.
I am blown if I can find it in Bentleys or Haynes

[itchyfeet]

yellow, find it in the black box on one of the two round connectors.

Haynes 12.29 F1 0.9 bar brown over engine ge= yellow in loom

[Mr Bean]

yellow, find it in the black box on one of the two round connectors.

Haynes 12.29 F1 0.9 bar brown over engine ge= yellow in loom

Doh! Now I feel like when the missus tells me where she put something and points it out when it's staring me in the face . Thanks for that itchyfeet.

This leads me to the test procedure on Bentley section 17.10 which seems to indicate that the 0.9 bar switch is normally open whereas the 0.3 bar switch is normally closed. So I appear to have been running on a simple open upon pressurization basis with the 0.9 circuit effectively disconnected. Looking at the J114 control box circuit in Haynes would, if I understand correctly, indicate that the the incorrect relationship between the of the switching of both low and high pressure switches under a fault condition would sound the so called buzzer of doom.
Should fix it really but experience indicates that might involve another can of worms... Best let it fester in my mind for a day or two.

[itchyfeet]

You're welcome Mr Bean

The yellow will have been grounded, high switch normally open means when no pressure its open
when driving its closed
I have seen them grounded at dash as well as engine bay.

Check your light flashes before starting
low pressure is open when driving so if the wire fell off you would never know the only indication its still working is the before start flashing.

[itchyfeet]

one other way of silencing it is to remove the green to dash from coil or cut it at dash.
the green is the tacho feed and tells the dash the engine revs, it only buzzes over 2000rpm ( if pressure below 0.9 bar) so no tacho feed no buzzer.

[937carrera]

I've just gone through the same process on my WBX.

The 13th post on the thread below sets out the test method I went through when reconnecting my high pressure switch after joining my snipped green tacho feed. My bliss continues (no comments on my ignorance please)

https://club8090.co.uk/forum/viewtopic.php?f=39&t=163521

[Mr Bean]

Wow! That is a lot to take in. Those designer chaps must have missed out on the KISS principle all those years ago.
Anyway my faithful old van had an "Eastenders Rebuild" in 2008 and another after the cam gear rivets failed in 2009 jamming the works and busted the crankcase (got to admit warranty honored though).
Some 35,000 mile later is still running well but removing the engine to fix a stripped exhaust stud and change the water pump revealed the usual can of worms which I have now dealt with. I shall replace the unproven 0.9 PSI pressure switch before replacing the engine and treat the rewiring job (and all that that might entail) as a separate job as a separate job since it worked for this long

E D I T: Yes I do believe the light does flash prior to starting - will double check when engine back in.