Hey I've been searching and ECU search returns no results.

I've been advised that my ECU is most likely faulty, just wondering if the controller computer is the ecu directly under the passenger footwell?

Also can I simply go to the wreckers and get a 2nd hand ECU to fix the issue before buying it brand new? I don't want to spend $500. It's a 3.5L TH Manual - 1999

ECU is a silver box located on the tunnel (the raised section that goes through the centre of the car) up against the firewall (the wall between the engine bay and your feet). Being a TH, yours might be distinguishable by a clear plastic sheet over it, as mine does.

If you peel back the carpet in the passenger footwell, to the right of where their leg should be, you'll be able to see it. It has four wiring connectors going to it.

Unfortunantly you cannot simply swap out the ECU, as it is paired with the BEM (Body Electronics Module - responsible for lighting and electrical systems). Essentially, to swap the ECU, you will need the paired BEM, keys, and locks.

Whats the issue with your car?

so either way a big job or an expensive trip to the mechanic...

If the mechanic does it, they'll be able to pair the ECU with BEM, keys and locks?

It really depends on what the problem is. What is your car doing/not doing?

Once the ECU is paired with a BEM, it cannot be changed again. The lock is permanent.

If you want to change the ecu then you need to also use the bem, keys and locks that came from the car from which you extracted the ECU from. All or nothing really.

If you buy brand new, then you can obviously match any new BEM with any new ECU and then have a new igintion barrel with keys. This stuff is expensive.

Basically the car is stuttering under load, no power below 3k rpm. We've checked the mechanical side, even had the cat looked at to check for blocking. The issue seems to be electronic because after I reset the ECU by removing the battery terminal (5 mins), the car went from bad to worse - nearly had to call a tow truck as it was kinda like bunny hoping.

I was quoted 500 for a new ECU by ultratune - new - but i'm assuming that won't include BEM, keys or barrels.

I'm thinking that if the cost is going to be above $1000 there is no point in repairing it.

Have you checked the passenger side footwell for any coolant leaks from the heater box?

Like I said before, you can use a second hand ecu, but you need to also get the bem, keys and locks (importantly, the ignition barrel) from the same car you pulled the ecu from. Manual ecu's are different to auto ones. You'll need to find a 3.5L TH manual wreck at a dismanteller, and rip out the bits you need from that car. Might be worth buying a wreck from the auctions.

Once the ECU is paired with a BEM, it cannot be changed again. The lock is permanent.

If you want to change the ecu then you need to also use the bem, keys and locks that came from the car from which you extracted the ECU from. All or nothing really.

If you buy brand new, then you can obviously match any new BEM with any new ECU and then have a new igintion barrel with keys. This stuff is expensive.

Or just find someone with/get a Openport, read existing immobiliser code, put replacement ecu in, reflash rom with old immobiliser and done... can always turn off imobiliser function all together!

Ok well I've found the ECU - there is a possibility that the rom has errors in it so I don't think that would be a good idea

Where is the BEM located then?

Also will an auto ECU work with a manual transmission?

Manual ecu is harder to get we do have a couple. Best option is to flash old rom to new cue to save key change

I'm worried that the rom might be corrupt if posible? Any recomendations as to where I could get that done?

Ok well I've found the ECU - there is a possibility that the rom has errors in it so I don't think that would be a good idea

While it is possible that the ROM has errors, it is quite unlikely as it is incorporated into the processor chip and if parts of the ECU function are okay that tends to rule corruption out. It is much more likely that the interface circuitry is damaged or there is a dry joint.

If the ROM is successfully read from the ECU, it can be compared with another TH manual ROM - unless there were several versions (which can be checked), only a few bytes (pertaining to the immobiliser) will be different. In any case, the immobiliser code is the only info that needs to be transferred to another TH manual ECU, and if that is corrupted you still have options.

BTW, what actually are the symptoms that prompted the diagnosis of a faulty ECU?


Also will an auto ECU work with a manual transmission?

They can with the right wiring, but a bigger problem is that the auto trans ECUs have completely different connectors to the manual trans ECUs, so lots of loom changing would be required to use an auto ECU.

BTW, what actually are the symptoms that prompted the diagnosis of a faulty ECU?


Basically I've had loss of power below 3k rpm kinda like how in an older car if the choke was on. I took it to my mechanic for a service, checked the exhaust for blockages, checked the intake and cleared the re-usable filter and ruled out mechanical faults. It's a manual tranny so gearbox has been ruled out leaving an electronics issue (most likely ECU as water was entering in large amounts to the passenger footwell)

I reset the battery the other day and the problem became much worse and far more noticeable. It also seems to bunny hop randomly like the fuel is getting cut out but I don't think it's the fuel pump and the filter was changed only 5000km ago

Who can do an ECU flash in melbourne?

Basically I've had loss of power below 3k rpm kinda like how in an older car if the choke was on. I took it to my mechanic for a service, checked the exhaust for blockages, checked the intake and cleared the re-usable filter and ruled out mechanical faults. It's a manual tranny so gearbox has been ruled out leaving an electronics issue (most likely ECU as water was entering in large amounts to the passenger footwell)

I reset the battery the other day and the problem became much worse and far more noticeable. It also seems to bunny hop randomly like the fuel is getting cut out but I don't think it's the fuel pump and the filter was changed only 5000km ago

Who can do an ECU flash in melbourne?

Unplug your o2 sensor. Plug is in the passenger footwell under the carpet and see if that fixes it. Mine was doing a similar thing until i replaced it

Basically I've had loss of power below 3k rpm kinda like how in an older car if the choke was on.

If the engine will run, I very much doubt that the ECU's ROM has become corrupted.