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Oil pressure switch


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Hi,

Defender 110 200Tdi 1990 (H)

I'm confused. Oil pressure switch not working, bought new one, still not working. Thought maybe I had the wires mixed up with the stop solenoid, swapped them over, oil light on dash now comes on, however, engine won't start! Swapped the back, engine starts straight away, no oil light!! Any ideas?

Thank you very much.

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Oil pressure switch wire is White with brown trace

 

fuel shut off solenoid wire is White with Black trace.

if the oil light isn't working with ign on, then the wire is probably broken inside the outer cover, try a new length of wire from the bulkhead multiplug to the oil pressure switch

wiring diagram in section 5 here, use the 2.5 diesel diagram http://www.landroverweb.com/Pdf-files/Manuals/Defender-90-110-workshop-manual-5.pdf

oil press switch = item 53

fuel shut off solly is item 73

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Indeed, oil light on dash works, albeit with the wrong cable! I have now removed all the conduit and tape to expose the whole length of wire (white with brown splodges) from the switch to the multiplug. There are no breaks and using a tester lamp, there is power at both ends when the ignition is on.

If I put a new wire from the switch, how and where do I connect the other end at the multiplug?

Thanks and Happy New Year!

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one of the multiplugs adjacent to clutch pedal assembly, just find the matching colour coded wire. use a blue sleeve male bullet connector crimped onto the new wire & fit to the multiplug 

as the existing wire allows 12v then it should still work, Have you connected it to new oil pressure switch & checked ?

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I still don't get where to plug the bullet onto. One end with new spade connector to new switch, which is now in place, the other end to the multiplug which contains the existing wire. Which bit do I cut? Sorry for my confusion. 

The screwdriver points to the switch wire on the multiplug.

14832802563871825762247.jpg

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I think you need to check what the fault is before you start cutting wires at the multiplug.

If you have the ign. on and you then earth out the oil pressure switch wire - just hold the spade connector against a decent metal bit, does the light come on?

If it does not come on then pull the multi plug apart and check continuity of that wire with a meter.

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Thanks, I'll have a play with the meter and dig deeper behind the light panel. If all fails, I'll run the new wire directly to the dash light. I don't get how the light comes on when the pressure switch is connected to the stop solenoid wire. That would suggest the wire behind the light panel is good.

 

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I have just been out and tested mine (2.5na) when I disconnect the oil pressure switch wire the light on the dash goes out and if I then connect it to earth the light comes on.

This tells me that the  pressure switch is just a normally closed switch that is connecting to earth when the engine is stopped - but more importantly there is no resistive load in the actual switch, I did not want to swap my solenoid wire onto the oil switch as that is a 12v supply that is "expecting" to find a resistive load on the end of the wire, the solenoid coil.

If I connected it on I would expect a bang and maybe blow a fuse when I switched on.

Still why yours behaved as it did is a mystery?????

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Ok so, I have tested for continuity along the whole length of wire from the switch to the bulb, including all junctions, terminals and connectors. My meter gives a positive tone in each case.

The light comes on with ignition if I earth the switch spade connector but still not if I reconnect it to the switch which is brand new.

I think I'm just going to scratch my head some more then insert a new wire from bulb to switch.

Thank you for all your help.

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Just thought - stick the meter on continuity and check that the switch body is connecting to earth, then check the spade connector is also connected to earth, then start the engine the spade connector should now be open circuit - ie not connected to earth.

But if you are not getting the light to come on then there must be something broken in the switch and it is open circuit.

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That may well be the case, I can't think of any reason for it not to work. The reason I bought a new switch was because the original light didn't work so when the new one didn't work either, I presumed a wiring problem.

I may as well order another switch to see if it does the trick.

Cheers.

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