Each door of 1998 - 2000 LS400 contains an ECU.

My left rear door window would auto reverse at top of travel.

I removed and replaced the window regulator and cleaned gears and lubricated pivot points which alleviated the issue temporarily.

Also acquired a door ECU.

I opened the door ECU and there appears three Aluminum Electrolytic capacitors and 3 relays..

Probably the capacitors should be replaced and the relays are tired.

Several images of circuit board and capacitors involved.

The driver's door ECU is probably different.


Image depicting door ECU relays.

16V 47uf United Chemi-Con KMR series are superseded by KMG.

50V 22uf

50V 100uf

Future project will include removing all 4 door ECU's and replacing capacitors and relays.

Elna and United Chemi-Con advise Aluminum Electrolytic capacitor shelf life is 15-16 years. Apparently the bottom capacitor seal degrades over time.

Early LS400's are now 30 + years....

Yamae any comment on the 3 (?) Relays?

Thank you.

 

Those capacitors are plain electrolytic capacitors and do not contain the quaternary ammonium salt. They degrade in accordance with the Arrhenius equation only and do not leak out. As far as I have checked some of them using an ESR meter, most of them were still OK. I'd rather spend my energy, time and money to others such as motor brushes and Posistors. Regarding the relay, I'd leave them until it causes some problem because I have never encountered any those relay's problems at different dealers and shops where I visit.

It's all up to you to do some work for the door ECU but the board is sensitive against the static discharge and I hope you don't cause any side effects handling it.

 

Hello Yamae:

You posted on replacing the Positors, but did not locate anything relating to disassembling the motors to replace the brushes.
Do you have any images of door window motor disassembled?

If motor bearings are sleeve configuration, then probably lubricant requires attention.

Thank you.

 

When I disassembled the motor, I was not able to take any photos just spending my energy to disassemble it. Sorry that I only have this photo which I took after the job. As you see, those 2 brushes were still OK but the carbon/graphite dusts were making a current pass and showing too low resistance between 2 terminals. The lubricant I used was one for my wife's sewing machine since I once have had a bad experience using a silicon oil which caused a siloxane problem. This Canon's page has a photo of a failed motor's commutator caused by the silicon oil.