Slow Window Relay modification on 'Positive' and 3 Switch Cars

Cars with 3 Window Switches: Cars having dual separate passenger window switches for both driver and passenger on each arm rest presents a particular wiring challenge. Both driver and passenger must not be allowed to operate the window at the same time in opposite directions. Ferrari's elegant solution was for battery voltage to flow through the driver's switch to the passenger side. However, this 'preventative' wiring renders the normal slow window relay modification useless.

In addition some other cars having 2 switches on the center console also used an unusual constant battery voltage at the motor which also disallows the normal window relay mod. According to the Owner's Manuals I have, 3 switch wiring existed in all 1978 308s and the positive wiring at the window motor exists on many (if not all) Dinos.

If you attempted the normal 'slow window relay mod' and are blowing buses, all is not lost. By reversing voltage to the relay coils, it works fine, and won't suffer from a dual operation headache. Below is the circuit.

The test for 'positive switching' condition - use a bulb test probe or voltmeter and check for voltage at the window motors with key on and window switch off.

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There are NO changes required at any switches or wiring between doors or wires from driver's door to the fuse panel so it wasn't repeated.

That is why the lower section focuses on how the relays connect to the motors. Just snip the wires going to the motors and insert the relays as shown. How you obtain 'enhanced' battery and ground will vary with your abilities and desires so I left that vague.