Scottish Elises

Suggestions gratefully received from the resident electrical gurus.

I have no dipped beam on the headlights. Fuse is good & have tried changing out both the switch & the relay for items known to be good with no success. I'll check the bulbs just in case they have both coincedentally blown at the same time but suspect a parted wire is a more likely conclusion???? So how do I go about tracing that?

Many Thanks


Charlie

What model/year is it?

Hi Robin
It's a 2001 Caterham. I realise most on here won't be familiar with Caterham wiring but I know plenty of you are pretty good with general electrical fault finding.

Got a wiring diagram?

Should be able to dig one out but will be in a PDF of the build manual. Can that be posted on here? If not PM me an email address & I can send it through. Post on PH suggests it could be the dip switch so shall have a tinker with that first.

Hi Charlie,

I've got a pdf of the Caterham wiring diagram that I can send to you
- It's fairly difficult to read so I've also sketched a basic schematic of the lighting circuit.

If you send me a PM with your email address I'll fire them both over to you.

Basically :

- the light relay is energised through the ignition and light switches in series.

- the blue wire from the light relay feeds the dip switch.

- the Dip Switch connects either the Main Beam cicuits ( Blue / White wire ) or the Dip Beam circuits ( Blue / Red wire ) to the headlamp plugs.


Theorising :

Assuming both dip beam filaments have not co-incidently blown.

- Unlikely to be an earthing problem since both dip beams affected.

- Main beam is functioning therefore the live ( blue ) feed to the dip switch is OK.

- You've checked the fuse ( Dip is Fuse #9) and it's OK

=> Likely to be the Dipswitch

Probe the voltages on the back of the dipswitch.

- Confirm you have around 12V between the Blue wire and earth

- Select Main Beam, confirm you have around 12v between the Blue/White wire and earth.

- Select Dip Beam, you should now have around 12V between the Blue / Red wire and earth.
If not pull off the Blue / Red wire and carefully touch it to the Blue wire ( it may spark )
If this lights up the dip beam then you should replace the switch
Be very careful not to allow any of these connectors to earth to any part of the chassis!

If this doesn't work report back and we can walk you through the next bit


Kevin.

Much obliged to you Kevin. It did turn out to be the dip switch at fault. Back working again after a clean of the contacts. Will try to source a better quality toggle switch though.

Chucks wrote:Much obliged to you Kevin. It did turn out to be the dip switch at fault. Back working again after a clean of the contacts. Will try to source a better quality toggle switch though.

Glad you got it working again

Kevin