fried the becu in ’06 camry

<sigh>

(2006 Camry I-4 LE)

So I'm looking for the blue yellow wire in the blue plug to find the lock wire -- find it and test it with ground and it works just fine (I metered it turning the key in the key cylinder on the driver's door).  Then I metered another wire while unlocking (turning the key in the key cylinder obviously the other way to unlock) and though it dropped from 12.4 volts .. it only dropped to 12.1 volts then shot back up to 12.4.  So, figuring this was the wire I tapped it to ground saw a tiny spark ..

After this, the door locks (buttons on both front doors) and the toyota OEM keyfob buttons do not lock and unlock the car.  Also, the trunk won't pop with the keyfob.  In a bitter twist of irony, the car remote starts flawlessly and this install was otherwise one of the easiest I've done in a while.

1) This is my buddy's car -- he's not wizsed, just wants to know if we can save money by purchasing the BECU from Toyota and installing it ouselves.

2) I unplugged the negative terminal of the car battery for a good 10 minutes, then plugged it back in to reset the car's computer -- didn't do anything.

3) I was trying to isolate the BECU module -- and it appears that it's either built into the large beige fusebox or somewhere behind it -- any thoughts? 

Thanks guys

Oh .. and once we figure out the replacement for the BECU .. which wire is for "UNLOCK" .. i have the blue / YELLOW for LOCk (single neg pulse) .. the DEI directions state a "blue" wire that needs a double negative pulse -- there is no such blue wire in that blue plug where the blue / YELLOW wire was found.

thnks

Oh... also .. checked all the fuses in both the interior and engine bay -- all were intact.

I checked a toyota parts website .. there are a couple items that may be the BECU:  keyless entry receiver (seemed the like the closest description) -- is this it?

Chris -- thank you for your reply --

Do you have a diagram (or a link) as to how I could wire this five wire setup?  I know currently it's a "type B" door lock system (is that three wire?)

Do you have access to a wiring chart that identifies colors of wires for the four doors/doorlock systems?  Thanks bro

You basically shorted out a 12vdc wire to ground.

Have you measured the wire again since you shorted it out?  It should still read 12vdc.  If it doesn't try hooking 12vdc to it (through a 3A fuse). 

One of several things most likely happened here -

1. You blew a fuse/fusable link that you can't find/isn't accessible
2. You burnt the traces off of the circuit board (unlikely in this case)
3. You damaged some severely (unlikely in this case)

Todays cars are very tolerent to short circuits, its a requirement the OEM puts on its suppliers.  Nothing should be permanently damaged by touching it to ground for 0.8 seconds (typical unlock length).

If it were me, I would check to see if you have 12vdc on the wire you made your connection to and pray that you don't have any voltage.  Like I said, I would then supply 12vdc though a small fuse to that wire, what do you have to lose at this point?  If this fixes the problem I would then do as much research as possible to find out what exactly went wrong.  If you can get a hold of a factory service manual you can find any fuses/fusable links in the line, and you can also find out exactly what that wire does.  If it rests with 12vdc on it is most likely the power supply for the keyless module or something like that.

Good luck!

Kpierson:

First off, thank you for your reply -- good info:

Yes, I re-measured the wire and it does it reads as 0vdc.  Prior to the short, it read 12.4vdc.  At this point, you're right, there is nothing to lose -- worst case: we buy another integration relay unit (BECU) or whatever Toyota calls that part.  Hopefully providing 12vdc through a 3amp fuse will restore power.

Thanks guys

Thats about the best thing that could have happened.  You've, in essence, found the problem (no voltage on a wire that should be powered).  This is most likely due to a blow fuse. 

Were you using a relay out?  If you were using a (-) 200mA output I would be a little concerned still, but if you were using a 15A relay out then I would almost guarentee it was a fuse/fusable link somewhere in the car.

Toyota has a very good technical site.  You can sign up for a 24 hour pass and download electrical drawings.  It may be worth the price!

Kevin --

I downloaded the service manual and found the plug that I fried a wire in -- it's supposed to be reading 10 - 14vdc constant (and of course, now, it is reading 0 vdc).  It's a power line to the Body ECU.  I'll keep you all informed of my progress, thank you again

When I fried the BECU .. I was testing this green wire w/ my VMM ... I read a 12.4vdc constant... then pressed the unlock button on the driver's door .. I watched the wire fluctuate down to 12.1vdc or so ... then it when back up to 12.4vdc constant.  Being retarded, i then proceeded to test this wire w/ ground to see if it would perform the unlock -- and of course I saw then a tiny spark and since then, the locks/unlock and trunk popper do not work.

Clearly, I now know exactly where those blue and blue / YELLOW wires are for the lock and unlock features that go to the BECU. 

What is the 'net address to that Toyota site? Thanks

peterubers wrote:

---

Kevin --

I downloaded the service manual and found the plug that I fried a wire in -- it's supposed to be reading 10 - 14vdc constant (and of course, now, it is reading 0 vdc).  It's a power line to the Body ECU.  I'll keep you all informed of my progress, thank you again

---

Does the service manual show if there is an inline fuse?

Got the complete service manual as well as the EWD's... (www.camrymanuals.com) .. great site... every *pdf for every camry

I traced this BLUE/WHITE wire (pin 14 of the 2G Connector in the Instrument Junction box i.e. the fusebox) ... it receives 12vdc (25A) from the engine fusebox (through the 25A DOOR1 fuse).  This blue/white wire (I thought it was green for some reason, I was incorrect) supplies 12vdc to the BECU for the purposes of door locking/unlocking.  It should read 10-14vdc constant, and of course now it is reading 0 vdc.

Unfortunately I don't have my buddy's car here now, otherwise I'd check that 25A fuse in the engine bay to see if that's what was blown.  You guys are awesome, thanks for the tips, I'll keep you informed.

(https://www.camrymanuals.com/manuals/02/68_Wiring.pdf)

peterubers wrote:

---

When I fried the BECU .. I was testing this green wire w/ my VMM ... I read a 12.4vdc constant... then pressed the unlock button on the driver's door .. I watched the wire fluctuate down to 12.1vdc or so ... then it when back up to 12.4vdc constant.  Being retarded, i then proceeded to test this wire w/ ground to see if it would perform the unlock -- and of course I saw then a tiny spark and since then, the locks/unlock and trunk popper do not work.

---

Notes: Meter this wire while turning the key in the driver door key cylinder
The Body ECU is attached to the back of the fuse box under the driver side dash. The plugs for the BECU are on the left side edge
Can also use the passenger door key cylinder unlock wire, which only requires a single pulse. It is blue/white (-) in the BECU, top plug, pin 21
 

double check the fuses inside and outside too, you might have over looked one.

problem solved!

It was the DOOR1 fuse in the engine bay main fuse box (right hand side of engine bay behind the battery).  It's a 25A fuse .. blew it when I tapped the doorlock power line to ground when fishing for the unlock wire.  All is resolved .. thanks for all the help guys.