Yes.

Here’s a photo. Lexus key is to my wife’s GX. The silver Toyota logo key and key fob were the only set the seller gave me. He said it’s all he got when he bought the 4R from the original owner. I had a spare key cut by a local locksmith and it also cranks the vehicle and unlocks the doors fine, as I tested it before putting it away in my safe. My glovebox has a lock on it but the key only goes in a tiny bit and will neither lock nor unlock it. Not sure if that’s related, I just assumed it was broke.

But still, if my 4R has an immobilizer how am I cranking it with blank metal spare keys? None of this makes any sense to me.

When I noticed the 4R ECU had an extra plug vs the Tacoma ECU I assumed the extra plug has something to do with the traction control module that’s mounted under the dash near the foot pedals. Which the Tacoma obviously wouldn’t have being a 5 speed.

I’m still not convinced my 4R has an immobilizer.

It’s an ‘02 SR5 Sport Edition. There’s no security inscription on the corner of the front windows, no dash security light, no “immobilizer” inscription around the ignition trim, no chipped ignition keys, etc.

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I think what he’s asking is why does any of that matter if the ECU isn’t looking for any of that. The non-immobilizer ECU isn’t checking anything.

That’s all makes sense if it’s an immobilizer ECU installed into a non-immobilizer vehicle. But my truck is the other way around. The ECU isn’t looking for anything.

Thank you for the explanation. I looked at the engine immobilizer wiring diagrams for a 2000 and it shows the ECM being the only control for the EFI relay which is where I was getting lost. (Dropbox - 2000 4Runner Electrical Wiring Diagram (EWD383U) - Printable - Simplify your life Section 82.) It would have been very helpful if Toyota had included a description and operation along with their wiring diagrams.

Would it be possible to jump the efi relay and that would bypass the immobilizer circuit and allow for starting for testing purposes?

It may be possible, but that's why I think swapping the ignition to a non-immobilizer ignition would be the safest bet.

Both the ECU and the transponder key amplifier communicate with the EFI relay. If your ECU is a non-immobilizer ECU, your transponder key amplifier can't verify the codes and won't let your EFI relay run.

This is a strange one.

Trace those wires back and see what they connect to, I think you'll find your answer there.

It may be possible that your ignition system was altered at some point, I had a friend who bought a used 4Runner which had a system like this - this video here shows what I'm talking about. Toyota and many cars easy key bypass( part 1) - YouTube

By safest do you mean jumping the EFI relay could risk frying something?

At the end of the day, I live in a non-emission county and can just pull the CEL and VSC bulbs. I’d just prefer to fix it correctly and have a functioning CEL. Especially considering I paid $400 for the Tacoma ECU.

I’ll try to check it out tonight and post my findings. I’ve left the dash pulled apart so it shouldn’t take long.

I’m off work Thurs and Fri and should have a little free time to tinker with it.

By safest I mean giving it the best possible chance of working.

I would try jumping the EFI relay and trying to start it with the manual ecm. If it runs then you know it's at least something to do with the ECM not commanding the EFI relay correctly.

Update…

Kinda…

Did some sleuthing through forums and some folks say the center plug contains wiring for the immobilizer but also the fly by wire throttle control. Which would be found on the 01-02 4Runner and 03-04 Tacoma.

If that’s true my Tacoma ECU should have the center plug regardless of the immobilizer issue, so I googled the part number on it. Everything online listed for sale with that part number is listed as a ‘04 2.7 4 cyl Tacoma.

I think I got screwed.

Gonna do more research to verify it before I call the auto parts store I bought it from and raise hell. I’m in NC and bought it online from a store in New Jersey. They said it’s as is no refunds, but they also specifically listed it as a 3.4 5vz ECU. And I even called them and verified over the phone that it was for a 3.4 v6.

89661-04B30

That’s the part number on it. I just noticed it’s also slightly longer than my 4R ECU.

That part number you listed is indeed for the 4-cylinder motor.

Alright we are definitely getting somewhere now. I know that on '99-'00 that center harness plug is for the immobilizer so I assumed it was also the same on '01-'02 4Runners also but it may be different. If it is true that the drive by wire function goes through that center plug, then everything else leads me to believe you actually do not have an immobilizer. Now you just need to get the correct ECU.

I’ll call them first thing tomorrow and try to get a refund.

How common is an immobilizer on the 03-04 Tacoma? Can you tell by the vehicle vin number? I’ll have to source one and I’d prefer not to deal with that headache if possible. Or if it’s just a crap shoot I guess I’ll just have to roll the dice.

Thanks for all the help.

Sucks about the ECU, but at least you have the answer now...

I just checked the diagrams (I'm much more familiar with the earlier ECUs) - some stuff on the plug that does immobilizer functions is non-immobilizer related, so whatever ECU will have items on all 5 plugs on the 01/02's. Throttle control isn't one of them though, but that doesn't really matter in this case.

On the 99/00's, the 5th (center) plug is only occupied on trucks with immobilizer. Learn something new every day!

-Charlie

did you ever end up finding the correct ECU for your truck?