Which Wire Is Positive
 

83 SL500 Euro Fuel Pump...

It Is Not Marked...

One Is A Cloth Wire With It Looks Like Faded Red Stripe....

The Other Is A Plastic Wire That Looks Faded Red Solid Or Brown

Thanks For Any Assistance

harbor freight
 

go to harbor freight and buy a cheap 5 dollar
ohm meter.... set it to volts... touch one wire
and with the other wire from the ohm meter touch the
car chassis... on one wire it will read voltage and the other will
read nothing.... the wire with voltage is postive...

you can check your self by setting it to ohms and the wire
that had no voltage will cause the meter to jump when touched
to the car chassis... :D

On Mercedes, brown is always ground.

Double check with the voltmeter just to be sure, but this is the convention.

If you don't have a volt meter handy, you can use a 12v light bulb between the wire and ground. If the light lights, you have the positive wire.

On ANY German vehicle, brown is always ground. Like "earth."

On ANY German vehicle, red is always hot, regardless of ignition switch position.

Switched positives tend to be green, usually with a stripe.

It's the Bosch way.