Thread: Headlights get brighter when handbrake is applied.

has to be some sort of earth problem , surely?

wires in most vehicles at this kind of age have had a hard life, so will be less than ideal.
Headlights more so than most other electrical items.
If you haven't, or the car doesn't appear to have updated headlight wiring, it's recommended to do so.

Can't imagine how the wiring is mucked up so badly that handbrake on makes them brighter tho! .. but dull headlights are usually a sign that the wires are past their 'use by' date

I had this in mind for my '99 at some point, but instead I opted for more efficient LED bulbs instead.
I chose Philips Ultinon LED globes due to Philips quality and the fact they are properly H4 standard, so the light beam doesn't just spray light everywhere, but directs the lighting as a halogen H4 globe does. They are 'literally' brilliant!!
Good colour(white) and very powerful. I can now easily see the cutoff area of the light where it just spreads the beam, and then nothing beyond that. With the old halogens(55/60's) and the decrepit wiring the light spread was of the normal fade to dark type.
Comparing my LEDs now to my brothers D2(same headlights basically) which has some type of +30 type halogens of the ice blue variety .. these Philips LEDs are at least another order of magnitude better.
The light is still usable(better than my old halogens on my D1, but I don't like their more green colour rendering.
These Ultinon LEDs are damned expensive tho. ($200 off ebay).

I also updated my dads(Ford Explorer) lights to LEDs but I didn't want to spend a fortune on his car(which will probably go soon anyhow).
I found some OK looking LEDs for his car(that appeared to have conforming H4 beam spread standards), and they do work very well, and much cheaper at about $75 off ebay. But they were a massive pain in the posterior to fit due to the heatsink design they used.
The Ultinons are very simple to fit by comparison.

The normally accepted wiring update simply involves some new wire, a pair of 40-ish Amp relays(one each for low and high beam), and some time to get it all together. (note I always use new 3 pin plugs for the globe connections too when I used to do wiring upgrades to my other cars).
Power comes directly from the battery, and the relays on/off operation is courtesy of the old light wiring.
Very easy to do, diagrams exist on how to do your own wiring, cost is usually about $50ish depending on what you already have at hand.

Or, for about $130 you can get a plug and play setup from Traxide
Headlight Wiring Upgrade Kit | TRAXIDE - RV | Traxide - RV
Also known as Drivesafe, here on this forum.
I have one which has been fitted for a few years now, no problems!
I still think you have another issue,though - probably earth related as Inc said.

Engine to chassis earth cable is faulty, loose or missing. Sorry, I don't know where it is on a D1.

There are other possibilities, but that is where I would start.

Likely the earth on the engine to chassis is faulty. Do something about it now before the park brake cable melts while cranking the engine.. it does happen. I fit an extra earth from the battery neg straight to the engine. The factory earthing is pretty poor

I have two primary cranking batteries in parallel. The second battery has an earth cable direct to the block. This is probably providing the starting current without melting the handbrake cable. The headlight load needs an earth path from the body to the block. It looks like the handbrake may be providing this path. I will have a measure around with a volt and clamp amp meter to check for rising earth voltages and stray current paths. Will probably end up with a new battery to block and body earth cable.

Aaron.

Originally Posted by JDNSW

Engine to chassis earth cable is faulty, loose or missing. Sorry, I don't know where it is on a D1.

There are other possibilities, but that is where I would start.

It's between the starter motor and the left hand engine mount on the chassis. The other chassis earth is by the steering box at the end of the battery negative cable (the middle of which has the body earth lug). Both chassis lugs get pretty grotty with age. A whacking great cable straight from the battery to the engine is definitely the way to go. The bolts of the air conditioning compressor bracket are quite close to the battery and seem to do the job well IMHO.

I took some measurements last night. With the engine running, headlights and cabin fan on high, the body floated up 0.9 volts above battery earth. With the handbrake off, around 12 amps were flowing through the handbrake cable. With the handbrake on, around 15 amps were flowing through the handbrake cable. No current flowed through the handbrake cable when cranking or with lights and fan off. It would appear that the battery to chassis and chassis to block earth cables are functioning, but the connection at the body is not.

Aaron.