hello
i was out four wheeling my 2005 v8 sr5 with a weekend group and ended up stuck in some water about 2 feet deep for 20 minutes. some water entered the cabin, but i didn't think it was too bad. the drivers floor got wet and the floor mat got wet, but not enough water to make the mat float off the floor or anything. of course i understand it's not advised to drive through water like that. it didn't seem like much water although i didn't expect to get stuck in it for so long.

anyway i made the way through the rest of my run and home at the end of the day. even took the car out a few hours later to the self serve car wash. in the middle of the night i was awakened by the alarm going off, which i silenced with the fob. i tried to start it this morning and the car would turn on but not turn over. no click nothing. battery also became drained and i did try a few times to boost it today to no avail. a friend who is more mechanically inclined than me came over with a odb scanner and he could not get my 4runner to communicate with it.

i searched the forum for a while and found some people with very similar symptoms who said their ecu became fried when this happened. although the ecu is located behind the dash and out of the water's way, there is a wiring junction near the driver's kick panel (near the foot rest) which is vulnerable to getting wet, and when it gets wet it sends a bad signal to the ecu and fries it. this area was wet so it stood to reason. although i'm not sure why the battery drained or if the car alarm going off last night has something to do with this.

so i took a chance and ordered a new ecu since it was only about a hundred bucks on ebay part 89661-35A50. i just have a few questions about the new-to-me ecu when it arrives.
1) does it swap straight in?
2) do i need to have the dealer reprogram it so that my keys work?
3) can a local independent shop reprogram it

any other insights would be helpful. thanks for reading.

From all my research on this I came up with 3 common things.

1. There's a low hanging plug on BOTH sides of the cabin behind the corner kick panel. Its bolted together with a 10mm head bolt, unbolt those, spray it out with CRC electrical cleaner or similar, blow out with compressed air. This should take care of your alarm issues since these plugs are related to body control. This also fixed my wiper, fuel level, and interior lighting stuck on issues which would explain a battery drain. Then put the closet hanger desiccant bags and bucket of RV desiccant in there with fans to move the air and close it up. Let it dry out in the sun.

2. Is the no start thing intermittent? Mine would no crank, no crank, then start after a few tries. It stopped doing it after a few weeks and has only done it once since then (4 months since getting wet). I've also heard of a GX470 having the same issue and he ended up replacing the starter and solenoid assembly with no issues since. We both believe it's a wet/corroded starter solenoid causing the intermittent no crank no start. Which doesn't really make sense if it stayed dry up in the V of the engine.

3. ECM. After drying everything out, cleaning connectors, and maybe replacing the starter (or just the solenoid) do you have any ECM fault codes? I would shy away from ECM replacement unless I had an ECM internal error fault code telling me to replace it. I've read of others saying it fixed their issue but I wonder if it was moreso just the cleaning of the corroded connections to the ECM from humidity in the cabin -> see cleaning connectors and desiccant steps above.

Yes the new ECM will most likely require Toyota reprogramming many things. Good luck!

This is the first time I've heard of this and its scary because I've been into water of similar depth and not had issues luckily. Is there anything that can be done to prevent this? I might take some time and put some dielectric in there for what it could possibly do to help.

Start with the simple clean your battery contacts and your ground contacts, I really don't see where your computer has a problem yet...may also be the battery, charge it.

I'm gonna suggest then the starter and the solenoid contacts. Once you've established that they are working or not working, You can also check a different obd tool just to be sure your friends obd2 tool was working correctly.

My garage floor Gets a lot of humidity In the springtime And I believe this is ruined a few starters for me because of the contacts inside the starter corroding With all the humidity.

Changing the starter is challenging, but I think I seen where someone has clean the solenoid contacts without changing the starter out, You may try looking into that, not sure if it was on a 4Runner.

Turned out to be the ecu. Swapped the part out and the engine turned over again. The truck is now at the local Toyota dealer waiting to be reprogrammed. Surprising how little water this took, and how identical my symptoms were to the others.

so they put a new ecu in, cleaned the junction near the driver's kick panel and now that's fried. so i ordered another ecu on ebay. saga continues.

original part number is 89661-35a50. but i am seeing parts 89661-35a51 and 89661-35a52 as compatible. are these other ones like the superseded part numbers for the original?

I wonder if there is an easy way to 'waterproof' this junction? Plastic bag and electrical tape?

Might be a worthwhile mod for some people.

Why did the replacement ECU fail?

i couldn't say for sure about why it failed. it was possibly DOA (although very highly rated veteran ebayer at 99.8% 11k transactions). i think there may have been some residual water in there and the dampness just fried the second one in the same fashion as the first. but who knows, i have to call a mechanic for everything so i just listen to what they say and read these forums. the replacement ecu did cause it to turn over then stall at first, so that would indicate it originally worked? will the vehicle crank with a dead ecu?

as for future protection, other 4 genners have been lifting the wiring junction above where you would reasonably expect water if you got a bit flooded. the plastic sealing thing has been suggested; might do that after i'm operational. i was again surprised at how little water this took. i would almost feel better if the whole got floor got wet, but it was just the part by the drivers' floor mat.

I just ordered some CRC "technician grade" dielectric grease to fill the connectors with. Part number 05113. I've used this on dirtbikes to seal crappy gps or headlight connectors and it keeps dust/water out well. It does make a mess. I also plan to never flood these connectors again but....

unfortunately i am still dealing with this. i had to have a bunch of wires in the driver kick panel re-routed because i kept buying ecu's which would just fry again. this time the newest ebay ecu installed and tested correcty, and toyota married it to the vin. the car now starts and runs.

however my gas pedal doesn't do anything, and the engine, vsc, and brake lights are all on. truck is still at toyota and they are scanning things. but i am in a small town and i don't think they know too much about 4th gens.

do i need toyota to fix this stuff now that the immobilizer and keys are working? can i take it to my local shop now to get the rest of this stuff fixed? or does toyota need to do some other special programming to the ecu. the replacement ecu is the identical part number of the one originally from the truck.

thanks everyone

apparently another bad wire in the kick panel related to the throttle by wire ground.

the truck now starts and runs but jumps into gear and have no throttle control. etcs fuse keeps blowing as soon as i put it in. if the ecu is disconnected and i change the fuse, it is fine until i reconnect the ecu then the fuse blows immediately. does this mean my new-to-me ecu is bad as well?

Was it programmed at the dealer