Adding an electrical circuit

[B. Bigelow]

Hi All,

 

I am installing VDO electric oil temperature and oil pressure gauges on my

2003 Rosso Corsa. I need to find a 12V ignition-switched supply to run the

gauges and their lights when the ignition is on. Does anyone have a

suggestion for where to get the 12V switched power? Can I safely take 12V

directly from one of the existing positions on the fuse block?

 

Thanks,

 

B. Bigelow

[Skeeve]

Can I safely take 12V

directly from one of the existing positions on the fuse block?

 

I'm certain you can, however, there are one or two relays that are already "oversubscribed" as delivered from the factory, so you'd want to avoid placing additional load on them. However, I'm not certain which they are, as I am allergic to the magic smoke, so avoid messing with it whenever possible. There are several adepts here who know the correct rituals: Ryland? Docc? Anyone else care to chime in?

[luhbo]

At the head lamp for instance? Would be not too far away from your gauges then.

 

Hubert

[Punch]

Hi All,

 

I am installing VDO electric oil temperature and oil pressure gauges on my

2003 Rosso Corsa. I need to find a 12V ignition-switched supply to run the

gauges and their lights when the ignition is on. Does anyone have a

suggestion for where to get the 12V switched power? Can I safely take 12V

directly from one of the existing positions on the fuse block?

 

Thanks,

 

B. Bigelow

 

As Hubert wrote, at the headlight would be a sensible place.

There should be "spare capacity" in the headlamp fuse/wires for what is probably quite a low current.

You will need a supply that is always on when the ignition is on, so I suggest that you use the pilot/parking globe wire.

Cut the positive wire where it will be out of the weather.

Strip the insulation off the two ends. Twist them together and crimp them into one end of a FEMALE bullet connector.

Then crimp the instrument positive cable into a matching Male bullet connector.

 

Do the same for the negative, except put the female connector to the bulb negative wire and the male to the wire that heads off to battery negative.

 

Alternatively you can add a dedicated circuit.

Battery + to an in line fuse, then to common terminal (30) of a relay.

Then from normally open terminal (87) of the relay to the + of the gauges.

Connect negative terminal (85) of the relay coil to battery -.

Connect positive terminal (86) of the relay coil to anything in the fuse box that is always powered when the ignition is on.

Connect this relay coil + to the fused side of the fuse box.

This means when the ignition is on, the relay closes and provides power to the gauges.

 

Richard

[docc]

Yes, taking the power from the 4W "dipped light", park lamp, or "city lamp" circuit in the headlamp shell would be sensible as the current requirement should be quite low and the power to that circuit does not come through the headlamp switch or any relay, but only through Fuse 6 and the ignition switch. The draw on the circuit is less than 2 amps, so the existing 5 amp fuse should be good to go for your VDO set up.

 

Post back a nice picture of them, yes?

[B. Bigelow]

Hi All,

 

Thanks for all of the very helpful suggestions!

 

I like the idea of taking power near the headlight - 12V there is near the instruments, controlled by the

ignition switch, and the additional draw of the VDO gauges and their lights on that circuit should be small.

 

I will post a longer reply and pictures when I get the whole thing working. Providing the 12V supply and

ground are really the last steps, so I hope I will get to posting the installation soon.

 

The back side of the fuse block on my Rosso Corsa is pretty hard to reach, due to a short wiring harness

coming up from underneath. I can't even see if there are spade terminals on the backside where one could make

wiring connections. Is my bike worse than usual in this regard?!

 

Thanks again!

Bruce

[docc]

Hi All,

 

Thanks for all of the very helpful suggestions!

 

I like the idea of taking power near the headlight - 12V there is near the instruments, controlled by the

ignition switch, and the additional draw of the VDO gauges and their lights on that circuit should be small.

 

I will post a longer reply and pictures when I get the whole thing working. Providing the 12V supply and

ground are really the last steps, so I hope I will get to posting the installation soon.

 

The back side of the fuse block on my Rosso Corsa is pretty hard to reach, due to a short wiring harness

coming up from underneath. I can't even see if there are spade terminals on the backside where one could make

wiring connections. Is my bike worse than usual in this regard?!

 

Thanks again!

Bruce

 

I don't suppose it is all that uncommon for the power distribution to be a bit shielded. Luhbo's suggestion to get the power out of the headlamp shell is a good one. He's a smart guy, Hubert . . .

[B. Bigelow]

Hello Again,

 

Thanks to everyone for the helpful suggestions!

The gauges are now installed and working perfectly.

I have a series of pictures showing the senders,

wiring, etc. if anyone is interested.

 

Bruce