How to ….Repair a Window Motor in a 400 series car.

Amazing what one can do with junk springs and shower curtains!

 

I've done this job several times. Last time was to replace the cable which had chaffed and was about to break. The cable and winder is a Ferrari (I think Fiat) part and I paid $193 from Algar. The unit comes with a clip that holds cable on drum while twisting and turning it to get in thru the speaker hole and while stringing cable onto pulleys. That clip eliminates the need for the springs and tyrap (second pair of hands helps too). I KEPT THE CLIP for future use!
Ken

 

I need to do my left window, it grinds and I have to help it up. My old Beta Zagato did the same thing.

 

Good day Gary,

Indeed, when I refreshed my window motors I was surprised at how well they worked. However, I was equally surprised at the initial current draw once the Window motor starts. I did some testing and measured the current and found that the current peaked close to about 11A and if the motor stalled the current went even higher. These motors do have an attached thermal switch that should break the electrical circuit if the motor gets too hot. However, the switch disconnect speed would be fairly slow do to the thermal mass of the assembly and so over time the resulting high current draw will take their toll. As case in point is the window switches themselves. On my car and I suspect other models too, the window switch allows motor current to flow through it... the result is heat generated within the switch and across the contacts... which brings me to my car. One of my windows switches appeared to be jammed... as I dug further and opened up the switch I can see why it was jammed. From the looks of it the motor current through the switch melted the internals resulting in a failed switch (see pics). Now, the ground relay kit may be marketed towards a window speed improvement, another and perhaps more important benefit is that these relays allow the high current motor currents to flow thorough the relay contacts which are designed for larger currents... and only small currents through the windows switches (window switches only control the relay coil current which is much, much smaller than the motor current). The net result is that the window switches will last much longer... and an improvement in Window speed. Speaking of which... I found that the Window speed on our cars to be excellent even without the relay kit. However, given the potential failure of the window switches I am using my relay kits (which are my own design) on my car.

Cheers,

Sam

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Neat kit, Sam
I just used two automotive relays and a lot of wires - although I soldered each crimp connection. This was for the 308, but will eventually do the 400 as well, if I ever find my mojo

 

Would a single relay do the trick? After all lowering the window is not likely to draw high current?
Do you place the relay in the door or next to the switch? In other words, is the vintage cabling between the switch and the door beefy enough to handle surge current?

 

Good day Patrick,
Indeed, two SPDT relays is all that is needed. I opted to make a PCB (Ferrari Red no less ) to keep everything small a tidy. I think the entire assembly fits into a small plastic cube enclosure about about 1" on a side. I built 4 of these ... 2 for the 365 and 2 for my BB.
As for mojo... after seeing and examining my window switches ... and taking a bit of time to find a NOS switch, I simply committed to doing this. Now to be fair, I had/have my interior all apart and so it was not too much effort to add these. As per my usual M.O. I ensured full backward compatibility should some future owner wished to remove my slight modifications.
Cheers,
Sam

 

Good day Raemin,

You might be able to find a single relay to do the motor's polarity reversal... when I looked for relays I wanted something as small as possible, with adequate contact current ratings (I used 2x max current as my rule of thumb), and was a stocked part. The only part I could find that met my deisignobjectives were these SPDT's and so I designed my circuit to accommodate. If I get a chance I will post a pic of the final assembly and the exact measurements.

Indeed the current draw is lower when the window goes down, as gravity assists here. However, the motor still has a surge current independent upon direction. Thankfully the surge current duration is low, but still should be addressed. Secondly, there are no limit switches at the top or bottom of the windows travel and so if one keeps pressing the window switch then the motor will stall at the open and closed positions which increases the current dramatically. To address this, the window motors have a thermal switch on the outside of them that opens if the motor gets too hot... and so this is the mechanism that Ferrari relied upon to limit the high currents. This does work, but as I mentioned it takes time for these thermal switches to open... and so over time if one presses the switches for too long at the fully open or fully closed positions, the electrical components in the window circuit will see relatively high currents... which creates heat... which limits their life.

As for wiring approach... Since I prefer minimal and removable changes, I elected to leave the existing wiring in place from the switch to the inside of the door, and add my relay module and additional wiring inside the door as well. This approach allows the existing car's wiring diagram to be mostly intact...and thus minimizes oddities for future electrical troubleshooters.

As for the original wiring itself... well... I would need to formally test the wire, but from my observation, Ferrari wiring and its insulation is low quality and was somewhat optimistic with regards to the proper wiring size and current capability. One has to keep in mind that any wire and size can handle any current... however, the big question is can the wire handle the resulting temperature rise for the duration of the flowing current?... If not then the wire either acts like a fuse (and opens if one is lucky) or it starts to get super hot which causes the surrounding elements (insulation, adjacent wires, etc) to catch fire. Given the currents I measured (surge and steady state) I think the wiring is marginally OK at best.

Cheers,

Sam

 

G'day,this is from the new to me "probably the best in Australia" car I bought a couple of months ago.

The recond diff with the incorrect ratio's failed annd is back with the reconers in the UK at their cost except everyone is looking for the correct 4.3 CW and Pinion,hence the thread from a couple of weeks ago.

Another thing that's no good with the car is the LH window motor so out with the old and in with...well a Ferrari supplied one 2nd hand for free except it's pretty much doing the same thing,cutting out when closing.

Ideas??

Oh and BTW yep that is the Ferrari supplied 8mm spanner as my home workshop doesn't have the tools of the workshop!
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What about the temperature sensor, this is a failiure prone component. Have you tried to temporarilybypass it?

 

Good day Simon,

Before I would go too far, I would check your original switches, as over time they will become internally oxidized/damaged because of the motor age and the excessive current draw of the motorized assembly. It sounds like the issue is with one side only and so swap the switches and see if there is any improvement. If so, then the switch could be internally failing... sort of like how mine were (see previous post pics). If the motor still cuts out, then you know the issue is certainly related to the original wiring, fuse, etc.

Since the motor is not yet installed, bench test the motor to see if the issue results. If not, then you can (mostly) eliminate the motor. If so, then you know it is the motor and so it could very well be what Raemin suggested, but also the motor's brushes may be worn or not seating properly.. or the motor commutator is worn or dirty. It is also possible the windings have flakey too, but this is not as common as the first items I mentioned.

Lastly, if all of the above tests indicate that the motor works fine, then the issue is something mechanical with the motor's connection to the various cables. If the cables or the window binds in some manner, the motor's thermal switch will trigger, as the motor heats up because of it stalling.

I hope the above helps!

Cheers,

Sam

 

Simon
When I bought my '84 400i the LH window did not operate. The motor ran but no window movement. I quickly found that the coupling between motor and winder was broken. I got the couple from F dealer for $15. (my first part purchased and it did not break the bank, that came later) With the new coupling installed the window moved a bit and bound up. I had the hand crank and tried it and it was the same. I pulled door panel and was confused by cables so I pulled the RH door panel and found cables not the same. There are some posts on this forum with the correct cable routing.
Test the switch as suggested above. Second, if you have the hand crank, give it a try (if not improvise).
Ken