replaced engine and airbags-now she wont start! any advice please?

[hypobuang]

Hi guys, great to be a part of this site! this is my first post and need some help.

I recently bought a damaged 04 mazda 3 with deployed front airbags. the car is a sport and the side bags didnt deploy.

I then bought a base model 04, with a lower km engine and good airbags. I swapped the engine, airbags, SRS module and seatbelt pretensioners into my damaged car.

now it wont start! the engine winds over but theres no spark and the ABS/SRS/ENGINE CHECK lamps are all lit up.

do you think the car needs reprogramming so the ECU knows it has the new airbags/SRS module etc? or is the module coded to the ecu of the car it came out of? the ecu is the original for that car but the SRS module is out of the donor car).

I did try to fire her up with the donor cars ecu and dash but it wouldnt even crank over. soon as i swapped the dash and ecu back it did turn over but with no spark.

can anyone offer any advice?
thanks in advance!

[dar_vedar]

hello,
the airbag light will have to be reset using a odb2 tool which is cabable of doing it.
no the ecu does not need to be swapped -provided the its the same model etc.(not an engine from a 1.8L being put into a 2L etc)
if your check engine light is turned on, you may not have connected all the wires - if you have a obd 2 reader or can borrow one i'd say grab it and scan your car.

[SMOKEY]

Im pretty sure the ecu has to be coded to match the new engine

@2XS ??

Or you could try the ecu from the donor car (ie the ecu that matches your transplanted engine).

[dar_vedar]

a similar job was done on a mate's subaru and the ecu did not change nor was any change done to it.
but that's on a subaru

[MPS2NV]

The module may need the can system linked it could also be possible that srs module is responsible for engine shut down after deploying air bags, might be a trip to a workshop

[RadiantKnackers]

Did you replace the BCM module?

There are two control systems in Mazda's, the PCM (powertrain control module), and the BCM (body control module). I believe the BCM controls airbag functions, and it is located behind the dash on the drivers side (Though I am translating from US diagrams so it may still be on the passenger side), against the body.

Keep in mind that even with both of these transplanted, you may still need to have the CAN link restored by Mazda.

[2XS]

I'd say you've missed a wire somewhere.
Swapping ECU's shouldn't change a thing, but, I'd try that first if you can.

[Axspeed6]

Did you replace the BCM module?

There are two control systems in Mazda's, the PCM (powertrain control module), and the BCM (body control module). I believe the BCM controls airbag functions, and it is located behind the dash on the drivers side (Though I am translating from US diagrams so it may still be on the passenger side), against the body.

Keep in mind that even with both of these transplanted, you may still need to have the CAN link restored by Mazda.

airbags are controlled by the airbag control module its separate, well in the 6's it is and i'd say the 3's are the same

[hypobuang]

great info guys. why is it the aussie sites are so much better than the US sites for nutting things out! we must be clever buggers and hate paying techs to do crap that we can learn to do ourselves! just hope I wont have to have the car reprogrammed as i can see more $ there, but it may be the end result.

ive looked deeper into it and located (what im calling) the BCM. clever buggers have made it as part of the fuse box under the glovebox. ive checked all the pins on it and it has the same number as the donor fuse block/bcm. so I fitted up the donor one and still no go. I actually had all from the donor car hooked up right down to removing the transponder ring and sliding the donors key into it to bypass the immobiliser. the original (non donor) key i used to crank her over.

heres an update:

swapped the engine/5speed, ecu, dash, BCM, seatbelt stems (with the airbag tube things), 2 front airbags (old fronts were deployed), airbag control module and the transponder for the immo. I even swapped the keyless box behind the glovebox.


only thing I didnt swap were the pretensioners (couldnt see any wires coming from them, only from the side inpact sensors that werent damaged), loom and fuse box under the bonnet, werent changed either.


by rights it should start.


I dont have access to a scan tool.


I had two cars to work off. My damaged car being a 04 mazda speed with side air bags, and the donor car (smashed in rear) that didnt have side airbags.


maybe the airbag module will have to suit the speed with the extra airbags? ive looked at both modules and they are identical right down to all the numbers (except serial #).


all the dash is lighting up. but the immo light is going out as it should do.
theres just no spark, but i do hear the fuel pump priming...


could the speed have different timing than the donor car (it being a pretty basic model). only thing is ive swapped everything EXCEPT the wiring loom and the only difference i can see are the extra airbags...
and yes, they are both 04 models.


I just cant get my head around it... but will keep trying!

[hypobuang]

I think i overlooked something... the donor car had no ABS and the car im repairing has ABS... I think I will need to use all the electronics from the car im repairing and just reflash the ecu or SRS module as it may have shut down due to the airbags being deployed...

alternatively if I use the donoe electronics: despite using the abs rotors it may still need the donor (non abs) ecu to be programmed to accept the abs.

maybe this is something I have overlooked...