Control Box Question

[Raw Cerb]

What is the control box second from the o/s for? All other boxes are labelled but this one is not. The reason I asked in the the earth is disconnected, and I am hestistant to reconnect until I know possible consequences.

[ridds]

Little Black box that looks different to the others and has 2 metal "wings"?

If so it's a light control unit.

[Raw Cerb]

Thanks, yes it is.

I am trying to diagnose why my projector lights are not working, either on full or dipped beam; the other two lights work fine. (It had a headlight conversion 6 years ago, so). I will take the box apart to see if anytinh is burnet/meted etc. Thanks mate.

[ridds]

Almost certainly a burnt terminal. Mine had the same issues a few years back.

Just chopped the wire off and soldered it directly onto the pins inside the box (with a bullet connector for if I do need to disconnect).

[Raw Cerb]

Help.

I have checked all control boxes for obvious signs of burnout, and confirmed by means of voltmeter that no more is reaching the diped beam. Any ideas on what to check next?

[ridds]

Can you grab a pic of the box in question?

[Raw Cerb]

Thanks.

Not even sure if it is the control box(s). Pic attached though.

At this stage situation is:

No dipped beam (was a headlight conversion 6 years ago).
Fuses ok.
No power reaching bulb
Checked all control boxes for melting etc.

What next? Do you know which terminal to check with my multimeter?

[jammy_basturd]

I'll double check against my lights tonight if it will help.

In the meantime, the wiring diagrams are here, http://www.thetvrsite.com/wiring-diagrams you need rear-harness-CEPD003C-1.jpg. Dim/dip units are middle/near top of the image.

[Raw Cerb]

The wiring diagrams are soooo useful thanks. I managed to trace the problem to an aftermarket relay box hidden in one of the pods. See photo. There are dip and main signals arriving at this box, but only main/projector beam kicks in. So I assume relay is faulty. One solder nodule has a little dry corrision on it. could it be a dry joint?

If not does anyone know how I could wire up a three way relay (so that dipped stays on with full beam, even though dip signal stops once full beam on)

Come you budding electricians....help me.

[VPower]

That board looks very simple to be honest, just need to workout what goes where.

A relay has two large high current contacts, which switch the power on to the lights.
There is also a smaller coil contact that uses a low current supply to switch the relay on and a small earth contact for this low current circuit

If you use the main beam signal to switch on a relay that is supplying power to the dipped lights, then they will be on when the main in on.

However doing this means you would back feed the dipped beam circuit from your new relay. This may or may not cause problems!!!

So I would find the dip and main power wires from the exisitng control unit, you then fit Diodes to these, and then connect them together to feed the dip relay switching coil. Then further back on the main circuit you take a feed to a main beam relay so that when the dip switch in on it does not cross feed the main beam relay.
YOu will need to feed your relays directly from a large power cable directly fromm the battery, with a fuse at the battery terminal or as close to the battery as possible.

This has advantages in that the existing circuits are now only used as the low current switching circuits and thus should become more reliable. All your power for the lights come from your new cable directly from the battery and will be less prone to spikes in voltage.


BUt that board you show may well be doing all this!!

[Raw Cerb]

Sorted - thanks for the advice. Found a spot of corrossion on the rear of the circuit board connector block. Easily cleaned. The relays connect direct to battery, and the original power is now simply activating the relays.

Cant wait to go for a drive now