BWM adaptation with 70amp Relay- "Herzel's Mod"

great job Herzel-

here's his mod:

[EDIT: Inserted link: http://www.network54.com/Forum/12159/message/1141512669 -Mac]

BWM - one bettrer, details (long)
March 4 2006 at 2:51 PM Herzel Frenkel


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As requested I tried to detail this modification:
OK now. The switch has the following wires:
A pair of white wires which indicate that a key is inserted. We ignore these, leave them as they are.
The famous Brown wire which is the power supplied into the switch.
There is a Black wire and a Green one, both supplying power to the car. They are separate circuits but they both get energized in tandem when the switch is ON.
There is a Red wire which feeds the starter solenoid on START. We leave this one alone.

I used a 70 AMP relay, standard outline dimensions. It has two heavy contacts (numbered 30 and 87) and two 1/4" contacts (numbered 85 and 86).

Disconnect the connector from the switch.
Run a 10 Gauge wire from the Positive battery pole through a 60 Amp Thermal protector (sort of an automatic fuse that resets when the overload is off) to the brown wire of the switch AND to terminal #30 of the relay.
Connect either blue or black wire from the switch to terminal #86 of the relay. Connect #85 to ground. Connect the Blue and Black wires on the car side of the connector to terminal #87 of the relay.
That’s it.
Now, there is a constant VOLTAGE supply from the battery, via the brown wire to the switch AND to # 30 of the relay.
When you turn the switch on, current flows through the switch to terminal #86 and activates the relay.
Once the relay goes ON current flows from #30 to #87 and to everything in the car.
The Red wire supplies current to the starter on START and is not affected by this mod.
I just drove the car at night and noticed that the instrument light is more then just a hint and the heater motors actually blows air and not just noise.
The miracles of the 70 Amp relay.
Oh yes, do solder ALL connections and wrap them well with insulating tape.
I hope my instructions are followable.





HaXD
Herzel
Green '85 X1/9



Greg Silver
"solo X"
1978 1300cc, euro head