jdm19942

ok first time poster on this website and here is the scenario that I have gotten my self stuck in I have a 1995 lexus ls400 originally the windows would not work if you tried to use them at the drivers door so I figured the switch must have been bad and I noticed that switch in my best friends 2001 camry looked the same and it plugged in directly after doing this the windows no longer function and the sunroof and driver side lock actuator quit working as well I tried to find any fuses that might have been blown and could not find one if anyone has any ideas on what to try I returned the original switch and the drivers window can still roll down if I use the key in the door if anybody else has had anything remotely similar happen and have a idea please let me know

johnnyg66

Not sure i follow you. So only when you used that camry switch those other things happened? But with original one its back to where you was before?

I say the master switch. Mine was intermit not working till i swapped mine out.

RA40

iTrader: (6)

Welcome to Club Lexus.

That was quite a run-on sentence/paragraph there.

Luckily the driver door window still functions. Replace the fuses even if they look good. Try again. If not, find a 95-97 switch assembly and try that.

Let us know.

LScowboyLS

reminds me of the L.A. Clippers and their 14 game winning streak

jdm19942

no after I reinstalled the original master switch the windows are still broken and then I realized the sunroof and power door lock quit working for the drivers door. and yes a paragraph in one sentence agreed oh well. but the only window I can get to work now is the drivers window when I turn the key in the door lock. Is there a specific fuse for the windows or does anybody know where the relay would be I checked in the power block in the engine bay as well as the fuse block under the steering column

johnnyg66

Looks like you found all the fuses. Not sure if you affected the ecu by using the wrong switch.

Try Disconnecting the battery and wait 30 secs and reconnect.

Never know might work. So your locks and sunroof worked before you put in the camry switch?

jdm19942

yeah everything worked before the camry switch but by ecu do you mean the engines control module or the body control module?

Lavrishevo

iTrader: (1)

Yeah, disconnect the negative on the battery then reconnect. Really only takes about 10 seconds on the LS400. This will do a soft reset and see if she acts better. If not, start looking at shorts and a close look at your fuses involved. The main ECU is not dealing with window operation and alarm. I know the airbags have their own little brain and I think the locks, windows, alarm have some kind of module.

steve2006

The "Body" ECU deals with the electric windows.

Yamae

In order to perform safer and convenient operations, Toyota uses a processor and other semiconductors to control door motors. Toyota calls it the “Multiplex Network Door Computer”. The current to the motor is supplied by this. There are more than 50 processors in your car and it is just one of them.

In most of the case, an FET inside of it is failed or a 30A fuse named “Power” is open. The fuse can be replaced easily by an owner but in case of an FET, it is almost impossible. You'd better to find out one at junk yards or you try to fix it as I do.

Clawhammer

I have a slightly different problem. All my windows on my 95 LS400 work if you use the switch on each door. However, the master driver's switch will only occasionally operate the other windows, but will operate the master door locking and the master window disable function just fine. I have switched out the master switch with another used one and the problem remains the same. It's possible that I have two malfunctioning master switches, but I wonder if there is another possibility since the master switch works once in a great while. Is there a relay I can check, or would it likely be in the "network door computer" that the problem lies? Any experience of others would be helpful to narrow down the suspects!

MattLS400

If I were to explain my power window problems, I would have probably said the exact same as the aforementioned..


I too experience similar issues with my 1996 LS400....Does the main ECU behind the Glove Compartment control these functions ?

Yamae

No, the main ECU does not control windows.
Windows are controlled by the “Multiplex Network Door Computer” together with each window's door computer.
A 96 JDM Celsior has it near the fuse box under the dash. The door computer is located at each doors. So there are 4 door computers.

I have seen failed FETs in the “Multiplex Network Door Computer” and in door computers time to time. Most of them were failed by the excess current when owners tried to modify or add something without disconnecting the negative battery terminal. Sometimes mechanics did those too. They should know how moderns cars work more. Same thing can be said to owners too.

When a FET has a excess current, the junction between the Source and the Drain is badly damaged and it becomes like a resistor and shows a few ohms to a few hundred ohms. This limits the current and the fuse doesn't open in most of the case.

Clawhammer

Yamae, Thank you for the explanation of the window controls.
Do you have any advice about an effective way of testing the "network door computer" or the individual door computer to see which might be defective? Can we repair those units or get one from a junked car and plug it in?
Any information on a possible repair is much appreciated!

Yamae

It is very difficult to check it without equipments, the knowledge + skills and the circuit diagram.

I always wonder how can I explain things well to others? I myself am mostly OK to analyze and trace complicated electronics circuits but I am not good at explaining those to others.

The circuit diagram is not available at all and you need to trace the board all by yourself. Find out the FET or the IC related to the switch tracing the line from the switch and check the condition of them. One of the simple and easy way is to measure the conductivity between S and D of the FET. If it is not within the range, simply replace it. In case of a IC, you need a logic analyzer or an oscilloscope.

I have explained the way to check and repair those electronics circuits to mechanics but the result was mostly unsuccessful. Non one was able to understand me well enough and they even broke the unit more.