Car door ECU - Page 1
Forum section: electronics / repair

author: spilihps
author_rank: Regular Contributor
timestamp: July 16, 2017, 11:51:40 am
content: Hello!So a friend asked me to have a look at his front drivers door ecu Before purchasinga new.The fault:The window motor only runs down. Everything else in the door works as expected.I opened it up hoping for somekind of relay-issue. Found a "dual Power relay"(ACF231)So i desoldered it from the board and tested it on the bench. Ofcourse it did work. Both "sides" of it.However, i do remeber a board (totaly different application) that i was asked to replace a relay on. That relay also did work on the bench. But the board started working with the new. Have no idea if its possible for the relays to get "hung up" or something and maybe loosen up with desoldered from handling/heat.I tested the components close to the coils of the relay, diodes and resistor networks (in Circuit) and they test fine. However, there is a IC (Q1) Close that does not have any markings on it. So no ideas yet.Any input?I add a Picture of the board, with the relay removed.

author: Nusa
author_rank: Super Contributor
timestamp: July 16, 2017, 12:07:45 pm
content: My first thought is that there may be nothing wrong with that board. I'd test the user switch that controls the board. Then test any limit switches/sensors that detect the position of the window.

author: spilihps
author_rank: Regular Contributor
timestamp: July 16, 2017, 12:33:04 pm
content: Hello,Thanks for your reply.You may very well be right.Actually dont know how they came to the conclusion that its the modules fault. Maybe it is "In most cases we replace this module and then it works"kind of reasoning..

author: Armadillo
author_rank: Super Contributor
timestamp: July 16, 2017, 12:36:24 pm
content: Most of the time, it's the window motor actuators modules mounted on the doors.

author: amyk
author_rank: Super Contributor
timestamp: July 16, 2017, 03:06:22 pm
content: Is all that circuitry just to control the window?I'd be tempted to just wire the switch to a relay and bypass that completely, assuming you've tested the motor and switches already.

author: Fred27
author_rank: Unknown
timestamp: July 16, 2017, 04:04:34 pm
content: That circuitry may be so the window reverses when a kid looks out the window, leans on the button and closes it on his neck.

author: spilihps
author_rank: Regular Contributor
timestamp: July 16, 2017, 04:51:59 pm
content: Hello!No, its for many things in the door. Mirror, locks, window and so on.Yes it probably have that. However. When fault accured the window worked normally down, he could open it in "small portions" it didnt just Went down and stayd there.And pushing the button, you can hear it try to go down as normal, but up is a different story, nothing clicks or "tries" so no overload Circuit seems to activete. Will replace the relay again and have them have a look at the car once more.

author: eugenenine
author_rank: Frequent Contributor
timestamp: July 16, 2017, 06:38:48 pm
content: Quote from: amyk on July 16, 2017, 03:06:22 pmThere is more in a modern car door, you have the window motor, the locks, the power mirror, the mirror heater, the turn signal, courtesy lights, puddle lights, etc. Instead of running wires to each they only have to run power, ground, and data to each door.

author: sanman
author_rank: Contributor
timestamp: July 21, 2017, 02:42:39 pm
content: I was riding in my 2001 truck with my 6-year old granddaughter who spent a few minutes searching for a 'button'. She was shocked when she learned she had to 'turn a handle' to move the window up and down