Vintage Ferrari Window Motor Troubleshooting

This post compiles our advice regarding slow or stuck window motors on the following Ferrari models:

  • Any pre-1974 Ferrari with 2-wire window motors
  • 1984-1991 Testarossa
  • 308 GTB/GTS, 308 QV, 308 GT4 Dino
  • Mondial 8, Mondial QV
  • 365 BB, 512 BB

Common window motor issues

6721175 window motor
6721175 Window Motor

We have found three main problem areas with the older cable operated window lift mechanisms:

  1. As the motors get older they tend to lose torque and in most cases need to be replaced with the newer higher torque motor (our part #6721175).
  2. The windows may be slowed by the motor driven right angle gearboxes which reel the cable in and out simultaneously. The grease in these gearboxes hardens with age. Whether or not you replace the original motors, we recommend removing the motor assembly and cleaning out the old grease in the motor gearbox. Once cleaned, re-grease the gearbox with modern molybdenum disulfide grease. This is a time-consuming and tedious task, but should be considered a must-do if you’re experiencing any trouble with the windows.
  3. From the factory, the window motors on many models are wired to draw current through the switch. As the switches and associated wiring age, this causes resistance in the circuit which can slow the motors and eventually result in heat damage to the wiring and switches. A robust solution to this problem is to install a window motor accelerator in each side, which isolates the switch from the motor current using a pair of relays. See the instructions below.

Window motor disassembly and removal

If you decide to remove the window motor assembly for replacement or reconditioning, here are a couple tips.

  • Before you begin, we recommend making a diagram and/or photographs of the cable path for each door, as they are different left to right.
  • It is easiest to do this with the window glass half up. This allows the cable located on the reel to be at a position so that it is half reeled in and half reeled out. Place a block of wood to support the window in this position. Use some type of securing mechanism to tightly retain the two parts of the cable as they come out of the reel. This will keep the cable from becoming a jumbled mess when you pull the assembly out of the door.

Window motor accelerator instructions

Follow this basic wiring diagram and the installation instructions below to create a window motor accelerator, which will isolate the motor current from the switches. In most cases, this will allow the motors to run faster as well as prevent damage to the wiring and switches. We stock the recommended Bosch relays, contact us if you would like to order. Equivalents may also be found at your local auto parts store. Be sure to insulate all connections and secure all relays/wiring out of the way of any moving components within the door. We recommend carefully testing the installation before reinstalling the door panel.

Wiring diagram of window motor accelerator
Wiring diagram of window motor accelerator
(click for larger version)
  1. Remove inner door panel to expose the 2 wires that connect to the window motor.
  2. Secure the relay units in the inner door cavity with a tie wrap or equivalent.
  3. Connect the BLACK (ground) wire to a spot on the metal door frame, making sure to scrape any paint or corrosion in the area that the eyelet connector contacts. You must have good metal-to-metal contact in order to properly ground the circuit.
  4. Splice the WHITE and YELLOW wires into the two wires going to the window motor. It does not matter which wire color goes to which motor wire. Insulate the connection where the splice is located. Use of heat-shrink tubing or heat-shrink crimp connectors is preferable to wrapping the splice with electrical tape.
  5. To test the installation, disconnect the BLACK wire from ground and run the window motor up. While the window is moving upwards, reconnect the BLACK wire to ground. You should be able to observe an appreciable difference in speed, with the window moving faster when the black wire is grounded.

Need window parts? Have other questions?

We stock new window motors and switches as well as a large variety of used parts including window mechanisms. Contact us for a quote.