Headlight wiring - have I are a mistake

[Graze]

Well i have with the topic heading

 

Not a natural with wiring but years of training as an architect mean I can read wiring diagrams And make sense of them.

 

So I upgraded the glow lamps at the front to H4 halogen headlights and set about installing a relay. I understand how they work and duly sourced the blue/ white and blue/red wires comming from the harness and splitting to either front light. Broke into the wiring, fitted the relay neatly on the passenger side behind the headlight on the inner wing and tidied up all the wiring.

 

Connecting the relay feed to the positive supply I looked around and thought that it was relatively easy and neat to route it along the wing across the bulkhead and direct to the positive terminal on the battery. All good so far, relay works, lights are bright, wiring is very neat and orderly ( keeps the architect in me happy)

 

BUT, driving early morning in the country today (to beat te heat), I had the lights on as I usually do on country roads, and noticed the volts were only charging about 11 and a half, lights off, goes up to 13!

 

Have I made a mistake connecting direct to the battery and if so where should I connect it?

 

Graze

Edited November 3, 2013 by Graze

[Graze]

I know why te problem is

 

With Bosch fuel pump and halogen lights my alternator needs upgrading

 

Easy fix

 

Graze

[RogerH]

Hi Graze,

the halogen lights draw no more current than the original lights. They are brighter because of the gas used.

Did the battery charge OK before the relays?

 

The relays should be very simple to sort.

The Blue/White or Blue/Red from the switch (or dip switch) goes to the relay coil to energise it. The other end of the coil goes to ground.

So when you flip the switch the relay should activate.

 

The Blue/White or Blue/Red wire going to the lights should come from the output of the relay contacts.

A new wire should come from the battery connection of the starter solenoid (or similar location).

So when the relay activates the lights are fed more directly through relay rather than the column and dip switches.

 

Roger

[Graze]

Roger

 

To be honest I hadn't driven it much at night before doing the relay and lights. So i dont know. I believe They are wired correctly and i know its working as you can hear it "click" in, so it must be the draw from the fuel pump

 

Graze

[Steves_TR6]

Hi Graze

 

Do you know which alternator is fitted?

 

From what I have read a 35 amp alternator is the bare minimum for a PI car.

 

You can't completely trust the voltage gauge as volt drop in the wiring can cause misleadingly low readings, but your test of turning off the lights does point to a charging problem.

 

Before you replace the alternator do check it's connections are sound, especially the earth path.

 

Steve

[Graze]

Thanks for the tip Steve

 

Will check out the alternator and the earth

 

Graze