McPierson

iTrader: (3)

Hello,
This is a searchable description of a recent issue I’ve had on my 2002 GS430 that I’m building here. https://www.clublexus.com/forums/bui...beautiful.html

When I got the car the rear windows would work from the driver switch even without the key.

This was because the PO had hot wired the switch to be powered all the time by powering up the red/yellow wire in the driver door switch.

Why hot wire? It turned out the Body Ecu 1 was faulty and didn’t put out power anymore. So this describes what I’ve determined as I went through the process of figuring this riddle out.

Fortunately, the PO handed me a red flag I ignored in the form of a wiring manual.



First I tried replacing the door ecu and hoped the windows would only work with the key. That didn’t help, but I confirmed these two door ECUs are interchangeable.




The first real attempt was I replaced the hot-wired driver door harness. PO used the the blue/black wire in the door to get I switched power. So if you need unswitched power in a door, that’s 20 amp worth.

At that the windows stopped working at all. None worked except with the key in the door of the car. I measure voltage on the red /yellow wire and it was 1.9v, weird.

When I looked at the “power window” wiring diagram I was able to determine body ecu 1 or as it’s listed on the box, MPX Body No. 1.

I was worried there was a wire problem not the ecu so I dug in trying to find out if body ecu1 red/yellow powered anything else. In the “overall wiring diagram” I found out the passenger power lock switch is also connected to body ecu 1. So I measured resistance between the passenger door lock and the driver power window and measure only 1 ohm. So at that point I know the wires were intact.

I ordered body ecu 1 from eBay. I was worried about which to order as the part number on the ecu doesn’t show in the Lexus system and there were several different choices on eBay. I ordered 89221-30010 from a 2004 GS430.



It came with this and I was glad to have extra parts, but I only used the ecu.





My 02 had 89221-30009. So these appear to be interchangeable.

To change the ecu first remove the passenger kick panel.

You'll see this.



Remove the plugs at the bottom and the bolt and nut that hold the fuse block to the car. You need to pull it out from the wall like this.


note: disconnect the harnesses before the next step.

Now you’ve got to remove the black metal clip that holds the body ecu to the fuse block. You can remove the body ecu now. Just reverse and you’re finished.

McPierson

iTrader: (3)

Here’s the wiring diagram.

McPierson

iTrader: (3)

Just following up. I got the keys programmed, windows work perfectly. Locks all work. This was the fix.