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Discussion Starter · #1 · (Edited)
Hi All,
I’m after some electrical assistance if anyone has any ideas? I’ll try and describe this as best as I can...

I acquired a mk1 Bandit 600 for nothing which was destined for the scrap heap, I’ve had 2 of these in my youth so I have a bit of a soft spot for them, this one I wanted to re-build in all the ways I never could back in the days of being subscribed to streetfighter magazine.

I have just fitted the new headlight unit which doubles as a GPS speedo, the headlight uses standard H4 connector and everything works – no issues there.
The GPS unit is fairly straight forward, it has labelled wires coming out for power and the warning lights, so far I have all of the warning lights working except the oil pressure.

I have clipped and re-used the original connector from the old clocks and soldered the wires from the unit to their respective connection, however the oil pressure light does not come on when the ignition is on (before engine start) I am assuming due to no direct +ve current

The connections I have made are:
Yellow – High beam (working)
Light Green – Turn signals (working)
Black/Blue tracer – Neutral (working)
Green/Yellow tracer – Oil pressure (fail)
Orange/Green – Switched Live +ve (working)
Black/Red – No longer using (Tacho)
Grey – No longer using (Old Clocks LED)

As far as I can tell the wires are more/less where they should be.

The area I think I’m getting wrong somehow is with the Orange/Green switched +ve, the wiring diagram shows this being split into the Neutral light, the power to the Tacho and the Oil pressure bulb, whereas I am only using it for the power to the unit itself, however the neutral light works fine.

I have tried to search how the oil pressure unit works and as far as I understand, it should have some power in the circuit to illuminate, then when the engine builds enough pressure it disconnects itself and the light goes out – is this wrong?

I tested the green/yellow wire with a multi-meter and am getting no current.
Currently I have tried a couple of things:
  • Bridging connection between Orange/Green (+ve) to the Green yellow (pressure switch) and the light comes on – good!
  • Same as above but when I also earth the connection (at the connector) on the engine it blows the fuse. I tried this as thought this would simulate the pressure switch earthing to the engine once pressure builds, but I guess it is already earthed at the sensor and I shorted it.
I have ordered some new fuses but my next plan was to finally start the engine (only recently got to this stage) and test the pressure switch in the normal way, although I suspect the light will not come on at all as there is no +ve current in the Green/Yellow line.

Then I was going to try and bridge the power and oil sensor wires to get the light to come on and test again and see if:
A – the light goes out when pressure builds and it works.
B – it blows a fuse once there is pressure with the bridged positive connection. (assuming my understanding of the pressure sensor is correct)

Sorry for the wall of text, I just wanted to make sure I explained what I had done and what I have tried so far.
Any help is appreciated, I’ll answer any questions if I’ve left anything out, the electrics are not my strong point.

I’ve been lurking on the site as a guest for a good while and I’d really like to get this whole build uploaded with pics once it’s done for you all to have a look!
Thanks guys!
 

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think your problem with the oil pressure light is your thinking it’s a + feed. However it’s an earth switch.. you should be getting a negative feed from the oil pressure switch through the yellow/green wire. When the pressure builds the negative feed is cut and your light goes out.

try connecting the yellow/green straight to an earth and the oil pressure light should comes on
 
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Think of it this way,
There is +12v connected the light when ignition is on but the light needs a earth- on the other side of the light to light up, that's what the pressure switch does is disconnects the earth when pressure is applied.
 

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Discussion Starter · #4 ·
Thanks guys, from your explanations I think my understanding of the switch was off.

I'll have another go once the replacement fuses arrive and report back.
 

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if you have 12v n the grn/yel with the key on then the switch may be bad. did you use teflon on the pressure sensor threads? that will block its path to ground and the light will never come on at all.
 

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Discussion Starter · #6 ·
-UPDATE-

Ok, so I think I have fixed the issue.
On the original lights the orange +ve went into the bulb and the grn/yel came out leading to the pressure switch, on this unit the +ve goes into the main body and a new grn/yel comes out of the unit to be connected to the original pressure switch grn/yel wire.

It seems the issue was that the unit was expecting to receive a +ve current to illuminate the bulb so wasn't providing one. I decided to take the engine cover off so I could test the switch.
When I bridged the +ve to the grn/yel I get the oil light, then when I earth the wire at the switch the whole unit turned off - should have been expected as the +ve is powering the whole unit now, not just the bulb.

So, instead I have bridged the black/red live that wasn't being used (which used to power the tacho) now the oil light comes on with the ignition and when earthing the wire at the switch it goes out as it should.

I'll test it one last time when I can start the engine but I think its good.

Thanks all for the input!
 
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