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Electrical Mental Overload

Here is an idea that most people miss on their Classic British car that should be considered on any year vehicle:

I’ll start with the idea of 19.

The is the number of bulbs I count running in a ‘late model’ MGB parking lamp system. Think about this-

6 gauges,
2 heater knobs,
1 cigar lighter,
4 side marker lamps,
2 front marker lamps,
2 rear marker lamps,
2 license plate lamps.

Did I miss anything?

The wire from the headlamp switch that is already running the head lamps is also running these as well. One some cars, such as the late model MGB (1977-80), this wire is only about an 18 gauge that runs from the switch to the two fuses in the four place fuse panel. They actually place two fuses on the lighting system after the dash bulbs! This 18 gauge wire should be a 14 gauge and I have seen a number of these burned up and even wires after the fuses wiring burned out.

So the issues with older wiring compared to newer type wiring:

Overloaded switches.
Note that with some modern bulbs or additional loads from additional lighting this can be an even larger burden.
Overloaded wiring,
Factories that manufactured to the absolute minimum and then went a size smaller.
Bad connections from age,
no load relief- no relay system

A fix for what you didn't know what ails you:

Install a relay for the Parking lamps!
Yes, a parking lamp relay.
I see relays for the main beam, low beam but never parking and I believe this is because people are not well informed of the load this system requires.

Believe it or not, if you install a relay for the parking lamps, your reducing the load from several amps running through the headlamp/parking lamp switch to no more than 1/2 an amp to run the relay. This does it’s part to allow additional load to run through the harness to the driving lamps, increase the life span of the switch, and degrease the load on a portion of the harness to the fuse panel. It may even take some old corroded connections out of the equation.

So with a relay, you not only get slightly brighter dash lamps and slightly brighter parking lamps but also potentially slightly brighter headlamps!

Please do not get the idea that your tail lamps are suddenly going to be as bright as the Modern L.E.D. Setup that we sell, but this is a good first step if you keep the standard lighting system in the car.

If you decide to install a parking lamp relay in many 1960’s and 1970’s British cars, this is what I recommend using a modern relay:
87 Red or Red/Green 14 gauge wire to fuse panel.
86 From ignition switch Red on some cars and red w/green tracer on later cars- aprox 1968 on. Can be as small as 22 gauge.
85 Use black wire and run to ground. 20-22 gauge.
30 Brown wire- suggest 14 gauge. Run this to battery. If you like, add a fuseable link at the end closest to the power source (off starter or battery)

Naturally, I’ll throw in that our L.E.D. Tail lamp setup reduces the power requirements for both parking and brake, but only for the taillamps, not the rest of the system. Although these are a better choice for being seen, the relay is at least a great start and something that will help your complete electrical system as mentioned previously.

-BMC.