C230 Windows/mirrors/seats not working - solved
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Joined: Jun 2017
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From: Corvallis, OR
1998 C230
C230 Windows/mirrors/seats not working - solved
Bought a 1998 C230 last week that is in excellent shape except that the windows, mirrors and seats didn't work. Thanks to this forum, I saw a recommendation to disconnect and reconnect the battery and after I did so (being very careful to follow the instructions also listed on this forum), the windows and mirrors work again. Technically 1 window still doesn't work but when none of them were working, I'm pretty sure that there is something else the matter with that 1 window - hopefully a switch.
As for the seats, they only worked for a few minutes after turning the ignition key and then stopped working. I was unable to find a schematic to test the relay but I noticed that unplugging the relay, letting it sit for a few minutes and reinstalling it caused the seats to work for a few minutes. Ordered the $25 relay from my local parts supplier, installed it and seats now work.
I believe the reason I got such a good deal on this car was because of the multiple creature comforts that weren't working and thanks to this forum I was able to fix them for peanuts.
One question - is there a possibility that disconnecting and reconnecting the battery may reset the CAN Bus but that systems may fail after a while if there is a more serious problem? I kind of gathered that this is possible and I wonder how likely that is.
As for the seats, they only worked for a few minutes after turning the ignition key and then stopped working. I was unable to find a schematic to test the relay but I noticed that unplugging the relay, letting it sit for a few minutes and reinstalling it caused the seats to work for a few minutes. Ordered the $25 relay from my local parts supplier, installed it and seats now work.
I believe the reason I got such a good deal on this car was because of the multiple creature comforts that weren't working and thanks to this forum I was able to fix them for peanuts.
One question - is there a possibility that disconnecting and reconnecting the battery may reset the CAN Bus but that systems may fail after a while if there is a more serious problem? I kind of gathered that this is possible and I wonder how likely that is.
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Junior Member
Joined: Jun 2017
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From: Corvallis, OR
1998 C230
Well as I feared, one window and one side of the mirrors stopped working a few days after I disconnected and reconnected the battery. I disconnected and reconnected the battery again today and all windows. Mirrors and seats all are working again.
I also have the rear passenger window which has never worked over the few weeks that I've owned the car. I have determined that both front and back switches work so it's either the motor, the control module or the wiring.
As I understand it, the Resetting of the battery reset the CAN bus and over time, if there is a problem with a system, the CAN bus will shut that system down. Can I get an opinion of whether my understanding is correct? Secondly, would the control module for the rear window have to fail or would the failure of the window motor also cause the CAN bus to shut down parts of the system? Third, would a code reader give me a better idea of what failed?
I also have the rear passenger window which has never worked over the few weeks that I've owned the car. I have determined that both front and back switches work so it's either the motor, the control module or the wiring.
As I understand it, the Resetting of the battery reset the CAN bus and over time, if there is a problem with a system, the CAN bus will shut that system down. Can I get an opinion of whether my understanding is correct? Secondly, would the control module for the rear window have to fail or would the failure of the window motor also cause the CAN bus to shut down parts of the system? Third, would a code reader give me a better idea of what failed?
Thread Starter
Junior Member
Joined: Jun 2017
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From: Corvallis, OR
1998 C230
Thanks, The seat seems to be OK now after I replaced the relay. I wrote 'seats' in my second post but meant to type 'windows'. Probably typed 'seats' from force of habit.
Now I'm wondering:
1) how the CAN bus works when something goes wrong in one of the systems so I can wrap my head around troubleshooting it
2) Whether a bad window motor would cause the CAN bus to shut down that system or whether the window control module alone would have to be bad for the CANbus to shut down that system. Probably answering the first questions answers this question.
3) Would a way to determine if the problem (of other windows and the mirrors not working) is caused by something faulty in the window motor/module be to disconnect the battery, disconnect the window motor and reconnect the battery and wait to see if the problem with the mirrors/windows returns?
I haven't taken off the door panel but I understand that the window control module is attached to the window motor so unplugging the motor would also disable the module.
Now I'm wondering:
1) how the CAN bus works when something goes wrong in one of the systems so I can wrap my head around troubleshooting it
2) Whether a bad window motor would cause the CAN bus to shut down that system or whether the window control module alone would have to be bad for the CANbus to shut down that system. Probably answering the first questions answers this question.
3) Would a way to determine if the problem (of other windows and the mirrors not working) is caused by something faulty in the window motor/module be to disconnect the battery, disconnect the window motor and reconnect the battery and wait to see if the problem with the mirrors/windows returns?
I haven't taken off the door panel but I understand that the window control module is attached to the window motor so unplugging the motor would also disable the module.
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C230
Some questions I can't answer, as electrical systems are out of my league.
My C230 had the rear left window not working, so I popped the door panel, about 3 minutes, did a bypass to the switch,and wired direct to the plug connector.
It worked. It was just a bit of a faulty connection, that I cleaned with contact spray, and no more problems. Control module is a good first bet. These window motors are built like a tank. I am amazed that the drivers auto window just keeps on ticking, as I must up and down, or half way the window all the time, and never fails to work.
Disconnecting, and reconnecting may reactivate, but there is a problem greater than that, and your just playing around to end up doing the inevitable, which is replacing the module. If you can find a wrecking yard that has one, you can't be out of pocket for more that $20.00. Ebay has them for $40.00. Also, there have been many cases where some people have spilled coffee or coke etc. on the consul, and gummed up the switches. Have you pulled of the panel that covers the switches? It's about a 15 minute job, and lots of YouTube videos to walk you through.
My C230 had the rear left window not working, so I popped the door panel, about 3 minutes, did a bypass to the switch,and wired direct to the plug connector.
It worked. It was just a bit of a faulty connection, that I cleaned with contact spray, and no more problems. Control module is a good first bet. These window motors are built like a tank. I am amazed that the drivers auto window just keeps on ticking, as I must up and down, or half way the window all the time, and never fails to work.
Disconnecting, and reconnecting may reactivate, but there is a problem greater than that, and your just playing around to end up doing the inevitable, which is replacing the module. If you can find a wrecking yard that has one, you can't be out of pocket for more that $20.00. Ebay has them for $40.00. Also, there have been many cases where some people have spilled coffee or coke etc. on the consul, and gummed up the switches. Have you pulled of the panel that covers the switches? It's about a 15 minute job, and lots of YouTube videos to walk you through.
Thread Starter
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Joined: Jun 2017
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From: Corvallis, OR
1998 C230
I actually broke the master window switch wood piece when I was trying to remove it and bought a complete unit on eBay to replace it that included the switches that the seller guaranteed to work. Meanwhile, I disconnected and reconnected the battery which got everything working again- albeit temporarily. I guess I'm confident that the switches on the console work.
So many of the pieces on this car have never been touched that everything seems extra difficult to remove. Same issue with removing the RR door panel. The grab handle was stuck real bad and took extra long to get apart. The $20 investment in plastic trim removal tools was worthwhile.
How did you bypass the window switch? I connected a 12V battery to the power and ground pins with alligator clips inside the module and nothing happened but I would have liked to make a better connection.
So many of the pieces on this car have never been touched that everything seems extra difficult to remove. Same issue with removing the RR door panel. The grab handle was stuck real bad and took extra long to get apart. The $20 investment in plastic trim removal tools was worthwhile.
How did you bypass the window switch? I connected a 12V battery to the power and ground pins with alligator clips inside the module and nothing happened but I would have liked to make a better connection.
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C230
Wow, breaking that must have taken a lot of force, and once you remove the the shift pattern plate, and the shiftier knob, it should pop right off? I am trying to remember if the 2 screws that are on each side of the ash tray holder need to come out as well?
The one problem with the pieces of plastic, is the sun baking them and they become very brittle. I had to replace a few thing along the way.
I went directly to the window motor, inside the door, where the wiring harness connects to the motor. I disconnected it, and jumped it. I think there are 4 pins, that are on the harness. I am going by memory. Should be power, ground, and then up and down.
The one problem with the pieces of plastic, is the sun baking them and they become very brittle. I had to replace a few thing along the way.
I went directly to the window motor, inside the door, where the wiring harness connects to the motor. I disconnected it, and jumped it. I think there are 4 pins, that are on the harness. I am going by memory. Should be power, ground, and then up and down.
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