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25 Posts
Discussion Starter #1
Just had a question or two about the function of the heating elements and possibly preventing burn-outs.
I found this article about older VW's and wanted to know if the PTC still exists in the element.
I've heard of them burning out and wanted to possibly rewire with a timer, load reduction relay, or maybe add an indicator to remind one that they are on, or?
Also, does anyone have the wiring schematics on this for the B5 or B5.5's so I can evaluate it before I disassemble?
Any suggestions?
TIA :)


Contrary to the wiring diagram #89-18 dated march 31, 1989
and the text in the Owner's Manual, the remote heated mirrors
are *not* powered through the rear window defogger switch.

The mirrors heating elements are connected to the ignition
circuit (Terminal #15) and are powered whenever the iginition
is switched on.

This electrical hook-up has no effect regarding the
alternator load balance during driving or on the durability
of the heating element. Due to the PTC ( PTC - positive
temperature coefficient) resistor, the initial current draw
tapers off to approximately 300 to 400 mAmps, after the
mirror heater has reached a temperature between
95 degrees and 105 degrees F (35 degress and 40 degrees C).

Please do not alter the wiring connections required for this


225 Posts
The wiring diagram shows 12volts is fed though a 5 amp fuse S6 (power windows and heated mirrors) to E231 (switch for outside mirror heating) to J393/T23 connector/pin1 (central control module for comfort system located under drivers front seat). Also, the diagram for the rear window defrogger shows 12 volts fed though E15 (rear window defogger switch) to the heated rear window and J393/T23/pin1. I removed fuse S6 and my heated mirrors/power windows did not work. If the rear window defogger switch has some spare connections, I am going to cut the wire going to T23connector /pin1. Run a wire to the rear window defogger switch and back down to T23 connector/pin 1. If no spare connections are available, I will splice into the wire (12volts 30amp)coming off of the rear window defogger switch. Put an in-line fuse holder (5amp fuse) and connect that wire to T23/pin1. Note: I will remove the original wire going to T23/pin1 before connecting the new wire.


381 Posts
Does anyone know how these function in the '03's? I guess I should consult my manual. I sometimes have a habit of leaving the knob in defrost mode too. :nervous:
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