DIY: 360 - Repair the Windows ECU for less than 50 cents

I decided to do something about the misbehaving driver-side window up/down operation when pulling on the exterior handle. It only works about 5% of the time and it’s been driving me crazy the past few years. I remove the door card and start probing as to where all the micro switches are located. I found that the micro switch that senses the window up/down position is not detecting the window state reliably. When in the up position, the micro switch should be infinity, the down position should be zero ohm. Currently, when the window is up, it is zero ohm and infinity if I tap on the micro switch mounting bracket.

It’s easy to make the adjustments once you see how the micro switch interact with the window regulator mechanism. I made the adjustment and slap everything back together thinking that I’ve finally licked the problem.

Well, no joy. So the obvious next step is to replace the windows ECU. I don’t have to tell you how much that part will cost ... I’m thinking, “What the heck, let’s open this baby up and see if anything is amiss. I have nothing to lose”. At first glance, no burned components, which is a good sign. Since I don’t have a schematic, it’s troubleshooting in the blind. I power up the FLIR camera and took a picture of the circuit board while all the electrical connectors are hooked up. Jackpot! I spotted an IC chip running hot, and this is with the ignition key off! In other words, the window ECU is draining the battery as car is just sitting there! That explains why sometime the battery is drained dead when I forget to plug in the charger overnight.

I sourced a new part from Mouser.com and replaced the defective IC. So far, after testing it about 50 times at random time of the day, the window rolls up and down as expected. If you find that your battery is draining overnight unexpectedly and you have a misbehaving window, this might just be the ticket to a permanent fix. The pictures are self-explanatory, but feel free to ask questions!

WARNING: do not put your hands inside the window regulator and troubleshoot while the car battery is connected! How the windows behaves is unknown when the ECU is in a fault state. The window might roll unexpectedly up or down depending on which micro switch is defective and activated or inactivated. You might lose a limb or several digits. I disconnect the inter-door electrical connector before reaching in there and reconnect it to test the adjustments.

Ferrari: 2003 360 Spider
Part source: Mouser.com
Part Manufacturer and ID: ST-Microelectronic, general purpose OP-AMP LM2904
Window ECU: 185888

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Check the micro switch on the external door lever. I find that the plastic spacer piece (the one with spokes) on mine has a loose fit, not switching on/off reliably. I shim the play with some plastic tape so that it would not rock back and forth as much.

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If you have a thermal camera and verified that it's running hot like mine, then most likely it's the problem. Without a schematic, it's a crapshoot at best. Otherwise I suspect it's the microswitch hidden behind the mounting plate on the regulator. I would at least verify the proper adjustment and operation of the microswitch before you dig further.

 

I would think that the 430 is awfully close to the 360 in design as to the windows regulator and operation of the microswitches. It's possible that the 430 window ECU is superceded with a new design. I shot a video of the regulator microswitch in action using a borescope, but I can't post it due to the attachment size limitation. If you give me your email address, I'll be more than happy to send it to you.

 

Well, after a little over 2 years, the old problem came back. I took apart the windows ECU and it's the same component that failed. After replacing it again with a new part from a different supplier, it fixes the problem. At this point, I'm not sure whether I got a marginal part to begin with or something else is causing the op-amp component to failed. Perhaps its a bad circuit design. Its difficult to make an assessment without a schematic. Does anyone knows if the 430 window ECU is the same as the 360?

 

Arrrgh... Can't tell you for sure since its reinstalled on the car. Going back on some old photos, looks like a bunch of SMD components; capacitors, transistors. There could be some collateral damage on the second hot spot as you suggested. If it blows again, I'm going to replace it with a superseded unit.

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I found an old video that I've created showing how the regulator arm interact with the micro switch. This is the driver side window. Hope it's useful to someone.

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