2006 V6 4Runner won't start - Mechanic is stumped

P

Pale Rider

New member
Please be patient with this long post, but I'm a bit frustrated and want to be as detailed as possible. My '06 4Runner was running fine one day, and the next day it died.

First thing I noticed was when I went to unlock the door with the remote key FOB, nothing happened. I had to manually unlock the door with the key. I thought this was odd as it never happened before, so I assumed the battery in the key fob was dead.

I then tried to start the car. It cranked over, ran for a second and then stalled. This has never happened before either. Tried starting again and it did the same thing. Tried starting it repeatedly for about 7-10 times. Each time it started, ran for a few seconds and then stalled. After 10 tries it finally stayed running, although rough. After letting it idle for a minute I (stupidly) drove the truck from my house. About 2 miles away I felt it sputter so I immediately turned around and tried to make it back when it completely died on me before getting back home. Called a friend to meet me with jumper cables. With the cables connected, the truck would not even crank over - no clicking, no sounds, nothing at all. Battery is less than two years old.

Called AAA and had the truck towed to my local mechanic, who is an excellent mechanic, is very experienced and is an honest guy. After having my 4Runner for nearly four weeks, he has no answers. By process of elimination, he's ruled out the battery, starter, alternator, fuel pump, all fuses and relays and who knows what else. He's sure the problem is electronic in nature, and is leaning towards a bad ECM, though he says he's never seen a Toyota ECM fail in over 20 years of working on and owning Toyotas. He was thinking maybe a rodent got into the engine bay and possibly chewed some wire leading to the ECM. He's unable to tell if it's throwing any codes, because the ECM is not getting power, or something like that. My words, not his. He says he's going to call a guy next week and have him hook up his laptop and try to program the ECM or diagnose it somehow. If this doesn't work, he said my only option is to take it to the dealer, which he does not want me to do, because he knows I'll take a beating from them. But at this point, he is stumped and just as frustrated as I am.

I read some previous older threads and was hoping that maybe it was a bad EFI fuse, but I went to the mechanic's today and pulled the EFI fuse from the truck, and it looked fine.

Truck only has 135,000 miles on it and, aside from an OME lift kit is basically stock. No engine or performance mods at all.

If anyone has any suggestions, I'm glad to hear them.

Thanks in advance.
 
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i would have used my aaa towing to move it to the dealer for a diagnostic, and then if necessary another tow to local mechanic for the repair.
 
Just a slim possibility, but don't rule out the EFI fuse simply by visual inspection, sometimes fuses can blow out and not be noticeable just by looking at them, the best way to positively test a fuse is with a multi-meter doing a continuity test.
 
Whatever it is must fit the first symptom, where the unlock attempt failed. That’s the key (no pun intended) to figuring this out. Narrow it down to conditions that could cause that and you’ll have a short(er) list to check. [MENTION=66389]BlackWorksInc[/MENTION] & [MENTION=15785]J.A.[/MENTION] know a lot about the 4R electrical system, any ideas gentlemen?
 
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After 4 weeks, it's well past time to have someone else diagnose the problem. Tow it to the dealer for a diagnostic service. "Some guy with a laptop next week" sounds like a really bad next step.
 
Appreciate all the responses.
[MENTION=114846]Bluesky 07[/MENTION], I agree with you about the key, but if I recall, once I got the truck running the key fob was working again.
[MENTION=175740]Seymore Butts[/MENTION], the guy with the laptop is apparently someone my mechanic has used before in similar situations to diagnose electronic issues. I'm willing to go ahead with him as a last resort before taking the truck to the dealer.
[MENTION=149207]AuSeeker[/MENTION], good point. I can go back and throw in a fresh 20A fuse for the EFI.
[MENTION=153267]iamatt[/MENTION] - What's an immobilizer?
 
hook up an obd2 scanner and if it doesn't light up then you might have a bad ecu. i blew a few of these in my truck because i got some water in the floor and it damaged some wiring in the drivers side kick panel and that will fry the ecu. this has happened to a number of people on here. lots of threads on it. if you were driving in water the day before almost certainly the case.

when the ecu gets messed up from water damage it will behave erratically (door locking and fob issues and truck starting and stalling) before it completely bites the dust. when it bites the dust the key will not cause as much as a click to come out of the starter. infuriating.

you can get a new ecu on ebay easy enough but you have to take it to the dealer to get programmed because the immobilizer stuff is built into the ecu. i'm not saying it's the ecu, but if it is you'll have to fight with every mechanic about it and they will swear up and down it's not the ecu. in my case it was the ecu and i spent a lot of money unnecessarily.
 
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[MENTION=139606]Pale Rider[/MENTION]
How long have you owned this truck? A 2006 with this low of miles is suspect. If you have recently purchased where is it from? Lots of flood vehicles out there, ECU and wiring problems. Lots more from high rust areas that were only driven in winter, look for ground straps and clean behind them. The immobilizer will allow the engine to crank but not start, so I don't think that is it.
Sounds silly, but take both battery cables off and touch them together to reset everything. I had some electical gosts and that did the trick.
 
did they check if there's fuel pressure? i know you mentioned the mechanic checked the pump but did he check the pressure?. also, could the starter gave out during those times you were trying to start it so many times and overheated? you could have scanned it rightaway when the problem started, at least it will give you a code to start from. Could also be a bad crank sensor.

Pale Rider said:
Please be patient with this long post, but I'm a bit frustrated and want to be as detailed as possible. My '06 4Runner was running fine one day, and the next day it died.

First thing I noticed was when I went to unlock the door with the remote key FOB, nothing happened. I had to manually unlock the door with the key. I thought this was odd as it never happened before, so I assumed the battery in the key fob was dead.

I then tried to start the car. It cranked over, ran for a second and then stalled. This has never happened before either. Tried starting again and it did the same thing. Tried starting it repeatedly for about 7-10 times. Each time it started, ran for a few seconds and then stalled. After 10 tries it finally stayed running, although rough. After letting it idle for a minute I (stupidly) drove the truck from my house. About 2 miles away I felt it sputter so I immediately turned around and tried to make it back when it completely died on me before getting back home. Called a friend to meet me with jumper cables. With the cables connected, the truck would not even crank over - no clicking, no sounds, nothing at all. Battery is less than two years old.

Called AAA and had the truck towed to my local mechanic, who is an excellent mechanic, is very experienced and is an honest guy. After having my 4Runner for nearly four weeks, he has no answers. By process of elimination, he's ruled out the battery, starter, alternator, fuel pump, all fuses and relays and who knows what else. He's sure the problem is electronic in nature, and is leaning towards a bad ECM, though he says he's never seen a Toyota ECM fail in over 20 years of working on and owning Toyotas. He was thinking maybe a rodent got into the engine bay and possibly chewed some wire leading to the ECM. He's unable to tell if it's throwing any codes, because the ECM is not getting power, or something like that. My words, not his. He says he's going to call a guy next week and have him hook up his laptop and try to program the ECM or diagnose it somehow. If this doesn't work, he said my only option is to take it to the dealer, which he does not want me to do, because he knows I'll take a beating from them. But at this point, he is stumped and just as frustrated as I am.

I read some previous older threads and was hoping that maybe it was a bad EFI fuse, but I went to the mechanic's today and pulled the EFI fuse from the truck, and it looked fine.

Truck only has 135,000 miles on it and, aside from an OME lift kit is basically stock. No engine or performance mods at all.

If anyone has any suggestions, I'm glad to hear them.

Thanks in advance.
Click to expand...
 
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My mechanic called me last night. It's a bad ECM.

Said his programmer guy hooked up his laptop, started diagnosing and after an hour or so, he confirmed that the ECM is shot. So now I'm going to bend over and brace myself. My mechanic is going to order a new ECM, install it himself and have his guy program it. At best, I will save some $$ from having the dealer do this work, but it's still an expensive repair.

[MENTION=248421]hankd[/MENTION] - One of the first things the mechanic did was try to obtain some codes from hooking up the OBD scanner, but he couldn't get a readout. Was completely dead.

[MENTION=91185]V8Man[/MENTION] - Definitely some valid points, but I've owned the truck for 5.5 years and haven't had any problems with it, other than the occasional CEL light with VSC and ABS lights illuminated. The original owner traded it in to the dealer, and that's where I bought it from in 2016. I bought it with 109,000 miles on it. It's not my daily driver and gets parked outside. I only drive it about 5-6,000 miles per year. The battery died on me about two years ago, thankfully in my driveway. Other than that, I've done front and rear brakes, change the oil, and only about six weeks ago I had a new rear exhaust installed.

My 4Runner has not been driven in water or been through a flood, but my mechanic did ask me about driving through water because he said he noticed when the truck is parked overnight that the inside of the windshield is covered with dew/water. I honestly never noticed that. He said when he takes the old ECM out he's going to open it up and see if it's had any water damage.

[MENTION=623698]4r-4ever[/MENTION] - I don't know if he specifically checked the fuel pressure, but he ruled it out and, as it turns out it's a bad ECM. He said the starter is fine.

Anyway, that's where I'm at. I already gave my mechanic the green light to proceed. I'm obviously disappointed that it turned out to be something this major, but at this point I just want my truck back.
 
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this doesn't have to be major at all. a new ecu is almost 2000 dollars new but you can find them on ebay for about 200. it is a user replaceable part and then you just need to tow it to a toyota dealership to program your keys to it.

every thread about ecu failure on this form has the underlying cause of water damage in the drivers kick panel wiring junction near where your left foot rests. so the water doesn't actually get near the ecu which is located in the dash. now maybe your ecu fried for some other reason, but if there's water shorting the wires near the kick panel, your new ecu will fry in a day. at least that's what happened to me, and it happened 3 times. total nightmare.

good luck with this! let us know how it goes
 
hankd said:
this doesn't have to be major at all. a new ecu is almost 2000 dollars new but you can find them on ebay for about 200. it is a user replaceable part and then you just need to tow it to a toyota dealership to program your keys to it.

every thread about ecu failure on this form has the underlying cause of water damage in the drivers kick panel wiring junction near where your left foot rests. so the water doesn't actually get near the ecu which is located in the dash. now maybe your ecu fried for some other reason, but if there's water shorting the wires near the kick panel, your new ecu will fry in a day. at least that's what happened to me, and it happened 3 times. total nightmare.

good luck with this! let us know how it goes
Click to expand...


This is very interesting. What's the source of the water and how can this be prevented (shielding or wrapping the wiring junction, etc.)?
 
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hankd said:
this doesn't have to be major at all. a new ecu is almost 2000 dollars new but you can find them on ebay for about 200. it is a user replaceable part and then you just need to tow it to a toyota dealership to program your keys to it.

every thread about ecu failure on this form has the underlying cause of water damage in the drivers kick panel wiring junction near where your left foot rests. so the water doesn't actually get near the ecu which is located in the dash. now maybe your ecu fried for some other reason, but if there's water shorting the wires near the kick panel, your new ecu will fry in a day. at least that's what happened to me, and it happened 3 times. total nightmare.

good luck with this! let us know how it goes
Click to expand...

The mechanic already ordered a new ECM from the dealer for $1,000 and will have it programmed by his own guy who does this. I didn't know they could be had for $200.

Going forward I will definitely be keeping my eye out for water infiltration. Up to this point, it has not been an issue. My experience owning and driving the truck for the last 5+ years/30,000 miles is that it has been completely dry inside the cabin, as far as I can tell. Unless there's water getting in somehow under the hood.

Isn't the ECM located near the passenger side in or near the glove box compartment?
 
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