Gauge wiring question

[levdeb]

Got these wires behind the oil gauge that aren't plugged into anything. Where they are supposed to go (I think) already has a green wire that runs directly from my convertible roof module... (why?).



When I turn the key to ON, the red light for oil pressure does not light up, and I would love to get this fixed asap. But I can't figure why the PO had these taped off...

Any help would be appreciated! I have a complete color wiring diagram coming soon, but not soon enough.











Also, these 2 little wires are also not connected to anything. It does have 12v going to it when the key is on, so I've taped them off till I can figure it out...





Thanks all!!

[Alan L]

I may be able to help tomorow, when I get to my manuals/wiring diags.
Alan

[Alan L]

OK, your oil gauge wires like this;
Gn/Re, comes from your sensor (near RH chain case). Goes via the T14 plug.
You have a triple Re/Bk into the gauge
Bk/Bl is the bulb
You have a double Br (earth) and another unspecified wire from the same terminal. Not sure what that bit means - just shows a current track from the double Br to the oil temp indicator Br.
If the light is not working with this wiring make sure the sensor is connected and the T14 junction valid.
Alan

[Alan L]

There is a double Gn/Wt which loops from the oil pressure indicator light to the park brake/seat belt warning lights.
Alan

[Alan L]

[levdeb]

Originally Posted by Alan L

There is a double Gn/Wt which loops from the oil pressure indicator light to the park brake/seat belt warning lights.
Alan

So that double green / white was the unplugged one... I can't figure out why that would be done by the previous owner. I plugged it in, but still no light. And there is switched 12v to the double Gn/Wt, as well as the red/blk... which seems weird that one bulb would have 12v coming in on both sides...

Instead of the double Gn/Wt, they have a green wire coming directly from the convertible top control module in the passenger footwell....

Thanks for all this info Alan! I got the color wiring diagrams in the mail and will try and sort it all with that and the info you provided!!

[Alan L]

So you havee 3 oil pressure tracks thru the T14 plug. One at terminal 4 (oil pressure gauge) and 9 (switch - to your light) and 3 (oil temp). The one that goes to your light from the switch is the Gn/Wt.
My guess is the power is coming to the light thru the re/bk. The gr/Wt is providing an earth . Which will be broken when you have pressure (like the o/boost sw). And then the light goes out. So you should check you have 12V at the re/bk, and an earth circuit from the gr/wt . Hook that lug to an earth and check for continuity. If you don't have that you have found the problem. You then need to track back thru those bits of the gr/wt circuit to see where you loose it. It may be the sw? Ground the wire on the sw and see if the light works. Then if not, make sure the bulb is good. if it still isn't working then the break is in the loom - prob T14.
You could also ground out the gr/wt terminal on the gauge - and the light should come on. If it does, that confirms the gr/wt loop is incorrect.
Alan

[levdeb]

Originally Posted by Alan L

So you havee 3 oil pressure tracks thru the T14 plug. One at terminal 4 (oil pressure gauge) and 9 (switch - to your light) and 3 (oil temp). The one that goes to your light from the switch is the Gn/Wt.
My guess is the power is coming to the light thru the re/bk. The gr/Wt is providing an earth . Which will be broken when you have pressure (like the o/boost sw). And then the light goes out. So you should check you have 12V at the re/bk, and an earth circuit from the gr/wt . Hook that lug to an earth and check for continuity. If you don't have that you have found the problem. You then need to track back thru those bits of the gr/wt circuit to see where you loose it. It may be the sw? Ground the wire on the sw and see if the light works. Then if not, make sure the bulb is good. if it still isn't working then the break is in the loom - prob T14.
You could also ground out the gr/wt terminal on the gauge - and the light should come on. If it does, that confirms the gr/wt loop is incorrect.
Alan

OK, I did do a continuity check from the switch to the terminal that plugs into the bulb, and it was a good feed. I also also have 12v at the re/bk (with key on). And bulb is good...

I am still really curious about the green wire coming from the convertible top module. It was plugged into that light (instead of the gr/wt wires) when I got the car. And the light didn't work then either. None of the wiring diagrams I found (or bought) show a wire from the module to that light...





I am heading down now to keep digging... appreciate it Alan!

[Alan L]

So that green wire comes from the idiot sw and goes into that other module??
I have no idea about that thing. But here is something to try. Jump a wire from that plug on the gr wire, to the terminal on the idiot light. Does it work - when you have a live feed?
Alan

[levdeb]

Originally Posted by Alan L

So that green wire comes from the idiot sw and goes into that other module??
I have no idea about that thing. But here is something to try. Jump a wire from that plug on the gr wire, to the terminal on the idiot light. Does it work - when you have a live feed?
Alan

Yep, exactly, and not sure why? If I unplug that wire, the top still opens and closes... lol

I had the green wire plugged into the idiot light, with red/blk on the other. Thats actually how it was wired by the PO. No light. I do have a diode between the red/blk wire and its feed. That seems to be working. So crazy....!

I really do appreciate your time Alan. Don't spend too much more time trying to decipher it! I am dropping it off at Eisenbuds for a post purchase inspection, and maybe they can help track it down.

Thanks again!!

[Alan L]

So my brain was a bit fried y/day - 14 hr road trip south with my car.
I am sure that solid Gr wire is a red herring. Supposed to be somewhere else. What happens when you hook the double Gr/Wt in its place? That is what is supposed to be there. I suspect that solid Gr is an earth for your other black box - so shares a continuity with that circuit - thru the chassis.
Alan

[Alan L]