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This post is a long time coming.
A while ago I bought a spare Body ECU on ebay to keep on the shelf and finally got around to opening it up to see what makes it tick.
This was my first look inside so I took some pics for any tech junkies out there who want to see.
The Body ECU seems to be three major components all rolled into one
1) Fuse & Relay box
2) Junction box
3) Body ECU circuit board
*The unit snaps together with tabs so it took a little patience to get it apart without breaking it.
PS- If anyone has more Body ECU info or fixes, etc please feel free to post it and share.
Here is a pic of the Body ECU, plugs fuses, and relays removed.
Outer cover has been removed to show the junctions between the wires and relays that connect to it.
Zoomed in to show junctions & jumpers
Junction cover removed reveals the brains of the Body ECU.
Zoomed in to show relays(qty 5 total).
Zoomed in to see the processors and surface mount components.
And finally with the circuit board(ecm) removed showing the junctions on the back side of Body ECU.
Margate you into electronics? Wondering if Toyota is using quality IC's and components... That large cap looks like a United Chemi Con but correct me if I'm wrong.
Margate you into electronics? Wondering if Toyota is using quality IC's and components... That large cap looks like a United Chemi Con but correct me if I'm wrong.
Hi Lexuswiz, yeah I do this for my job working mostly on industrial stuff. Honestly I hate electronics. lol
You got me thinking so I opened it back up to have a look to check it out for ya'll and the large 470uf cap has a KYG logo on and rated for hi temp 105C it but looks like many other brands so I tested it and much to my surprise it is bad- measuring 0.2 ohms ESR failed the test on my meter.
However, the 100uf surface mount cap is still ok and so are the 2 smd tantalum caps on the back.
I took some pics of the two processors and they appear to be custom Denso programmable processors.
There is a "D" for a logo so someone let me know if not a Denso so I can correct this.
Solder work appears high quality as seen under microscope.
Other thing I noticed is I have no idea what the 5 relays on the Body ECM circuit board are for but I was expecting them to be transistor driven(repairable) but the two relays I traced out were not. They are directly driven by the processor, so if a relay coil shorts out it can fry the processor(not repairable) unless the processor has current limited outputs- either way the Body ECU fails if a relay goes out.
The processor driving relays.
While the circuit board is lightly conformal coated for moisture protection, there are several plastic cards in a stack all with jumpers that are not, so moisture could be a problem with these if they get wet.
PS- I really didn't think anyone would care about this stuff and wasn't going to post it so thank you all for your comments.
Possible Repair? I wouldn't bother with repairing a failed unit because of the many ways it can fail, much faster and cost effective to swap out with working spare then spend $100+ per hour having someone diagnosing and tracking the problem down because of the complexity of this unit and how it stitches into almost everything on the car.
Anyone else have info on the Body ECU they want to share plz feel free to add.
Appreciate you posting. Usually these forums show you how to replace whole modules/units and not IC repair/the guts LOL. Definitely a lot of dorks like me on here that love to tinker.
Appreciate you posting. Usually these forums show you how to replace whole modules/units and not IC repair/the guts LOL. Definitely a lot of dorks like me on here that love to tinker.
i agree; i am a electronics nerd too but i dont have the knowledge to diagnos the guts of a ecu or circuit board. Im more of a how to use type of nerd lol.
A dopey remedial question, please: if a problem arises where the ECU needs to be replaced, is it a straightforward replacement by a physical swap - plug and play (like a relay)? or are there additional steps such as programming necessary? I can imagine the dealer charging outrageous sums for 1) the ECU “new” part, and 2) labor, so wonder to what extent it’s a DIY job. Thanks.
A dopey remedial question, please: if a problem arises where the ECU needs to be replaced, is it a straightforward replacement by a physical swap - plug and play (like a relay)? or are there additional steps such as programming necessary? I can imagine the dealer charging outrageous sums for 1) the ECU “new” part, and 2) labor, so wonder to what extent it’s a DIY job. Thanks.
The cost of the Body ECU at dealer prices plus diagnostic fees could be huge $$$, only to find out the problem can be a bad harness, junction connector, or module somewhere else causing all the problems.
I only got a spare for testing purposes and to find out how the whole Body System is stitched together and the problems can come from any of the above.
Is replacing it a DIY "Plug and Play" with no programming necessary?
Appears to be and hopefully someone can confirm.
Any chance you have any photos of the body ECU mounted in position, and was it hard to access?
Hi Brucecav, I don't have any pics of the mounting location but for cars in the USA it is located on the driver side under the dash in a really fun place. lol
Hopefully someone has some pics of the location.
Also, even though I have a spare I haven't had to use it yet but there is another member recently who swapped his out in this thread and maybe someone else who has done it can chime in.
Link: https://www.clublexus.com/forums/rx-...s-2004-rx.html
02-09-21, 07:00 PM
Body ECU Thread with Pics
