I know this is a well traveled thread but before I haul and purchase a new one I wanted to check. No aftermarket stereo btw or other parts. Driving down the road - driver side window decided to go down. Switch on door panel does not light up nor will the window work. However, if after shutting the car off for awhile you can get it to roll up with the key and roll back down with key but once down it will not roll back up until engine is started and turned off. I have removed the door panel and the ECU. Cleaned the contacts which had some corosion since the vapor barrier was no longer there and i tried everything - same situation. My only conclusion is bad ecu. but again wanted to make sure i was not missing something else.
Ecu's come up of ebay-US,british or German sites. Used ones are not cheap. The 456M ecu(green) is not the same as the 456 ecu(black). I have a spare 456m ecu(ask me how I know). while waitng, check the connections that go to the window and lock mechanism under the hood in front of the door jamb-they corrode. Check the key locking mechanism,check the little relay at the striker plate. Do you have a malfunctioning alarm system?It took me 2 years to sort my doors out on my 456 Be patient-perhaps others here have other suggestions. You will become an expert in quick removals of the door panel.
There is a window ECU reset procedure on here somewhere that has worked for 456/456M owners. Maybe one of the 456 owners can chime in. Found one here: http://www.ferrarichat.com/forum/456-550-575/403930-window-early-456-gt.html If you search window ECU reset, there are a couple more.
I have tried the window ecu reset - did not solve me problem. Regarding the wiring harness i looked over what was in the door and did not see anything -plus I can roll the window up with the key from the passenger side. Finally the moisture barrier was at some point removed by previous mechanic which leads me to the corosion in ECU - the ecu plug for the window had some corrosion. When I pulled the ECU out it looks fine other than plug - of course if it had moisture under power it would be a problem. I have restored alot of old corvettes over the years and I must say I dont miss the concept of an ecu
Before you replace the ECU, check the wiring in the door. Mine was corroded and some of the circuits were compromised. This contributed to the eventual failure of the module. The problem you will face is that there is not a schematic for the door for the pre - M - model 456s. I had to pull the tape off the harness to find the issue. If you find it corroded, don't bother trying to solder in a new run - it won't flow correctly. There are harnesses available on Fleabay al the time.
I had an issue with the passenger door - automatically rolling down windows and occasionally the central locking cycling between closed and open after a close attempt. It was pretty erratic when it occurred. I found it was caused by break in the wiring loom where water ingressed into the plastic tubes that hold the wires. This would not necessarily have lead to issues if the wires would be insulated all the way, however in the loom there are a few splices. These splices which form mainly the common connections for the door, window and lock switches, these splices break apart and cause various malfunctions which get attributed to the ECU, which most often is actually not at fault. It took a bit of following the wires and measuring continuity (if you measure between the switches there should be continuity between the ones that carry the common color), but it was relatively easy to find.
see this thread http://www.ferrarichat.com/forum/456-550-575/299205-mis-functioning-window-when-door-opens.html post #15 shows the microswitch in the door lock mechanism
To all, Just catching up. I just replaced my drivers ECU at dealer. I don't have time and skills to do otherwise. Also, there were other items replaced (mechanical?). I will save old unit. Maybe can be of use some time. Cheers, Stan
