Electrics Help

[paul_r]

Hi all,

 

Been having issues with wiring (again) and i have a question, hopefully not to stupid.

 

I have been measuring voltages in/out of the sierra stalks and am getting a reasonable voltage drop. I have measured 12v min supply but the switched output, on lights, of 10.5v. Is this normal or do i have an issue. Ifthis isn't normal what would the likely cause be, dodgy stalks?

 

Thanks in advance

Paul

[IanS]

A good switch will only have less than 0.1V drop.

First thing is to always measure with the same earth point, I when doing this use the battery negative with a crock clip on the terminal and a long lead to the meter.

The voltage drop you are seeing is large and probably the result of oxide buildup on the switch contacts.

This happens to all unsealed switches over time.

Properly designed switches self clean during operation.

Maplin sell aerosols of switch cleaner that you spray into the switch as you operate the switch which can help and is cheaper than a new switch.

Most switches are not designed to come appart but with care they can be dismantled and the contact surfaces directly cleaned with very fine abrasive, only try this if you are confident that you can put it back together

[cb750]

Have you checked what the supply voltage is with the lights on? You may find its similar to the switch output voltage, in that case you don't have a switch problem.

[fry61]

As Ian said, measure volt drop across switch when lights are on -- any difference will indicate a high resistance contact -- no difference switch O.K & fault is else where -- battery or wiring -- are the headlights wired via a relay (or Two? ) this cuts out all the heavy load across stalk contacts & ensures h/lights burn at max brilliance & also prevents arc pitting in switch.

[paul_r]

Thanks for the replies.

I am running 2 relays fir the headlights without issue, although they arent as bright as I'd like. i had issues with the rear fog not working after a period on fixing. Light work fine when i take direct feed frim battery (12v). But when i try to switch relay with headlight feed i get nothing, even though headlights work. Battery is giving out 12.5v which goes into the switches but i seem to have lost 10% when it comes out

I'll try to clean the switches and go from there

[Grim]

headlights: Are you running sealed beams? if so, they're dim - replace with h4 assembly. If h4 bulb: check wiring to bulb - a common mistake is to wire the two H4 filaments in series.

 

Fog: check what relay pin positions you have - there are two layouts of pins, if you have the wrong relay the light will work for a short period before the relay burns out. Voltage drop may be due to incorrectly wired relay

[paul_r]

Thanks, already changed to H4. Using the VG loom so assume that they are in parallel.

 

Thanks for the advice on the relay will check when i get a chance.

Edited September 12, 2016 by paul_r

[Guest 2b cruising]

 

Nobody mentioned the earth yet.

This really is the most common fault with regard to lighting.

Check the contact between the lamp unit and cassis. If Staines chassis it is very common to get bad contact at any earthing point.

This also goes for under bonnet equipment too.

As always check the basics.

Battery volts as you have already mention the work your way along the circuit lives and earth if required, ie insulated earth return circuits. Not a common thing on cars.

I'm currently part way changing to led system and the amount of earth point I have found not quite as good as they should be is practically around the 60'/, mark. Even though all was functioning correctly I have cirtainly prevented some future brake downs.

Hope this helps, Ken.

[paul_r]

Good advice I'll check the earth and most likely run in another wire outside of the VG loom