Question about repacing the KL's ECU.
Anyone know if the BEM and keys must also be replaced at the same time?
I believe the BEM is a seperate component to the ECU in this model, but I assume they're all related and must be replaced as a set?

If you have an openport, then you can swap ECU and keep existing keys and BEM.

need to ensure replacement ECU has correct immobiliser code (ie read your existing rom, hex edit new rom, reflash on replacement ecu)

Replacing the BEM and keys will only be required if you can't arrange to have the ROM copied from your old ECU - the ROM doesn't need to be fiddled with at all, just copied into the replacement ECU.

MN156378 ECUs (used in all L/W series AWDs as far as I've been able to determine) are the same hardware as the MR98872x ECUs (x can be one of 5, 6, 7) used in L/W series FWD autos which should be more readily available.

I would not recommend using a J series auto ECU in an L/W series car: such ECUs use a different reflashing protocol (*) to the L/W series auto ECUs which could lead to unwanted drama with other parties, even though it is possible to flash L/W ROMs to them and I believe (but don't know for certain) have an L/W series car operate satisfactorily with such an ECU.

(*) simplified terminology

Hey thanks for this info guys.

Replacing the BEM and keys will only be required if you can't arrange to have the ROM copied from your old ECU - the ROM doesn't need to be fiddled with at all, just copied into the replacement ECU.
Who typically can do the ROM burn? Do the Mits dealerships have that capability or does it need a specialist shop?
And is the ROM chip removable or is it done while still mounted on the board ? (Which implies some kind of specialist flashing software)?

Not sure why you need to change your ECU over but you need someone who has the ability to read your old ECU, get the immob code and then change the code in the new ECU over, that is of course once you find an ECU as well.

Hi Mal, I dont need to change the ECU over! Let me explain:
As u know my plan is to keep the car as my daily and i'm expecting it to last for years, like my KH has. It's currently got about 46 k's on it, and with good maintenance theres no reason why it wouldnt last as long.
I thought I should pick up a spare new ECU now while they're still available cheaply from Mitsubishi for this model as insurance against any future problems. Judging by posts here these modules can fail for various reasons.
Given that its a critical component and with the high Aussie dollar bringing prices down I think it's a good investment.
I was recently quoted approx $480 for a brand new (OEM) module for this model.
Don't want to be trying to source one 5 years from now at who knows what availability or prices.

The only other critical component that seems to be a potential point of early failure on these cars is the transmission (eg the wave spring issue... ), unfortunately I can't store a spare transmission, even if I could find one!
Anything else I'm sure there will be parts around for years.

If you can get a brand new ECU full stop I would grab it, let alone for $480 as the RRP on these is over 1200 bucks. Add to this though there is no more chance of failure on your AWD than there is on the KH. In all the years I have been doing this business I have replaced 1 ECU that failed for unexplained reasons. ALL of the others have been affected by water (coolant) from the heater core leaking. As for the L and W series, that 1 was a TW AWD, motor ran fine but the trans side of the unit had died. It was the 1 and only L or W series ECU pack I have ever sold for unexplained failure Have sold a few for people with flood damage and as stated above for coolant.

I have I would think about 5 complete L and W series AWD ecu packs here on the shelf as we speak.

Who typically can do the ROM burn? Do the Mits dealerships have that capability or does it need a specialist shop?
And is the ROM chip removable or is it done while still mounted on the board ? (Which implies some kind of specialist flashing software)?
See the thread linked in my sig for more on reflashing... the flash ROM is part of the microprocessor chip in the ECU so can't be removed, but from the late F series (sometime in 1998) onwards all Magnas and Veradas were equipped with the wiring to support reflashing using a MUT-III unit (used by dealerships) or OpenPort cable and notebook - it is just a matter of plugging the appropriate kit into the diagnostic connector and the reflash connector, and running the software to do it.

Awesome, WytWun, thank you. Yeah, I'm thinking of future coolant leaks, now that I've seen how common an issue it is on these forums. And of course things like caps fail over time (leakage) and the ECU is already 9 years old!

Replacing the BEM and keys will only be required if you can't arrange to have the ROM copied from your old ECU - the ROM doesn't need to be fiddled with at all, just copied into the replacement ECU.

MN156378 ECUs (used in all L/W series AWDs as far as I've been able to determine
My new ECU has part number MN 156378 as you said, WytWun. Box also states 3.5L AWD. Its a genuine Mits package made by Bosch here in Australia, if u believe it.

I guess i now need to have the ROM copied in order to make it useful for me.
I have some questions for anyone who has done this or knows:
Does the dealership need to remove the existing ECU from the car or can they do it in-place? (I assume they wouldn't need to remove it and can just plug the computer into the maintenance/diagnostic port of the existing ECU (under the dash) for the read and plug the new ECU into the computer for burning to its ROM). Should only take a couple of minutes i expect.

The only way i can be sure if its worked would be to swap the ECU's over.
Is there any special procedure to swap ECU's? I'm thinking disconnect battery obviously, but anything special need to be configured after re-connection?
Also, whats the best way to access/remove the ECU? Passenger or drivers side?

My new ECU has part number MN 156378 as you said, WytWun. Box also states 3.5L AWD. Its a genuine Mits package made by Bosch here in Australia, if u believe it.

I guess i now need to have the ROM copied in order to make it useful for me.
I have some questions for anyone who has done this or knows:
Does the dealership need to remove the existing ECU from the car or can they do it in-place? (I assume they wouldn't need to remove it and can just plug the computer into the maintenance/diagnostic port of the existing ECU (under the dash) for the read and plug the new ECU into the computer for burning to its ROM). Should only take a couple of minutes i expect.

The only way i can be sure if its worked would be to swap the ECU's over.
Is there any special procedure to swap ECU's? I'm thinking disconnect battery obviously, but anything special need to be configured after re-connection?
Also, whats the best way to access/remove the ECU? Passenger or drivers side?
As your new ECU has the same part number, you don't really need to copy the ROM - just set the immobiliser code. However with an OpenPort cable you'd have to read the existing ECU to get the immobiliser code anyway so it is just as easy to write that ROM to the new ECU.

I don't know for certain, but expect that dealerships would only have the MUT-III setup for in-car operation. In that case you would need to find a dealership which would swap the ECU in and set the immobiliser code and return your existing ECU as-is (you could get them to do the swap your existing ECU is back into the car - extra $$$). Out of car reflashing requires a special harness which can be made, but I doubt would have been common in dealerships.

TBH, if you already have access to a Windows laptop buying the OpenPort cable is likely to work out cheaper and give you more control.

Because there are mounting screws both sides of the ECU, you do need access from both driver's and passenger's footwells, however from memory with some finesse you don't need to remove much from the driver's side (I think I removed the footrest).

You don't need to disconnect the battery, as unplugging the ECU has the same effect - also leaves the HU with its code intact. The connectors have catches that need to be depressed to pull the connector out.

I thought i'd disconnect the battery anyway to be sure to avoid any spikes when plugging/unplugging.
Wouldn't it be cheaper to have a dealership do it rather than me buy a cable and software that i'll only use once?
I can remove the kick panels prior to taking it into them to speed things up, shouldn't take more than a few minutes to do, so the labour charges would be minimal.

Get a quote. You might be surprised - either way :hmm:

The cable can be used for logging and checking/clearing DTCs if you buy the Evoscan software as well, not to mention tweaking your auto trans shift points (ECUFlash is a free download), so it can have a use beyond the immediate requirement.

-The cable can be used for logging and checking/clearing DTCs if you buy the Evoscan software as well-.
Where to buy the cable and software?

i brought my cable to read CEL code from http://www.evoscan.com/

i believe this is the cable you will require for the reflashing http://www.evoscan.com/evoscan-gps-obdii-cables/details/15/1/performance-vehicle-pc-diagnostic-interfaces/openport-13u-universal-usb-datalogging-and-reflashing-cable

OpenPort 1.3U is fine for logging all 3rd gens, but can only be used for reflashing J/L/W ECUs. OpenPort 2.0 will reflash a lot of things and can log direct to a microSD card but is a bit slower for logging (ie fewer samples per second by about 1/4); it is also more expensive.

OpenPort 1.3U is fine for logging all 3rd gens, but can only be used for reflashing J/L/W ECUs. OpenPort 2.0 will reflash a lot of things and can log direct to a microSD card but is a bit slower for logging (ie fewer samples per second by about 1/4); it is also more expensive.
Ah, "OpenPort" is a standard i guess? $137? What about the software? Where do i get it and how much? And does it run under Windows?

Update; the dealership says that i need a replacement BEM and shows me some Mitsu documentation to support that.
Got as far as installing the new ECU before they had to stop and go back to the old ECU :(
I believe the standard Mitsu procedure would be to replace ECU/BEM and re-register the keys.

The dealership does not believe we can program the BEM code into the new ECU. They believe its the other way around and the BEM module contains data about the ECU. They also state that the evoscan or flash software only works on the older models, but wouldnt work anyway due the BEM containing the ECU details.

From my pov, it doesnt matter that the BEM contains the ECU details so long as we can flash the data across to the new ECU. The new ECU would then be a clone of the old ECU and the BEM should work happily with it.

So, has anyone done this on a T/KL or T/KW and knows for sure that it can be done? If so, exactly which software was used?

Have done this heaps of times, the dealership is either guessing or simply does not know. The tune or datanfrom your old ecu can be flashed directly into the new ecu

Have done this heaps of times, the dealership is either guessing or simply does not know. The tune or datanfrom your old ecu can be flashed directly into the new ecu

Its a bit disappointing. I dk why they needed to pull the old one out and install the new one if they couldn't do it. Bit of a waste of time.

Mal, you have a PM.