looms and lengths

[Vanny]

got a question, and its one about size!
Every BX16v i have played with has the ECU sittting under the drivers seat, with the loom then running through the drivers side wing space and into the engine bay behind the LHM reservoir, it then runs all the way round the front of the car to link to the AFM making the whole thing rather long.

Gary C has very kindly sent me a loom which is two row and matches both the ECU i have and the injector loom piece i already have, however it looks like it goes trhough the bulk head behind the battery. Never seen one and am wondering if anyone can give me some indication of where to route this short loom? Can you get a two row ECU in the 'long' format?

[Jezziebx16v]

Possably no use at all Vanny but every 16v i have come across has had the ECU under the drivers seat and the ABS unit under the passengers seat. Could make a difference to your loom routing questions.


Jez

[Vanny]

ignore me, idiot slip i obviously ment i've always seen them under the drivers seat with the ABS under the passenger! Have edited the original post!

[Toddman]

Vanny
The "FULL" loom runs from the fuse box through the bulkhead behind the battery under the tray and AFM etc with various plugs then down round the front end and all the way along th efront up behind the LHM tank then behind the inner wing and through the bulkhead and down to the ecy under the drivers seat.

I have a full 3 row ecu and loom here and have worked on and removed several 2 row items, and that is how they run so you either have an incomplete loom or it has been modified in some way.

Hope that helps

Cheers
Luke

[Vanny]

The "FULL" loom runs from the fuse box through the bulkhead behind the battery under the tray and AFM etc with various plugs then down round the front end and all the way along th efront up behind the LHM tank then behind the inner wing and through the bulkhead and down to the ecy under the drivers seat.

thats what i'm used to as well, but in reality there is no reason for it to go all that way round if the ECU was by the fuse box, which is kind of how this one is layed out (as though the ECU should go under the passenger seat). It certainly hasn't been cut up, but there are a few easily replacable connectors missing that should plug into the fuse box, other than that it's intact and all the connections i would expect are there!

[Timmo]

i dont know if its any use but on the 205/309gti's the ecu is under the dash drivers side? iirc they are all 2 row ecu's???

wouldnt you be best askign gary?? he is likely to be able to tell you how they had it connected??

[Mike P]

Is it 405 Mi16 loom as they are different IIRC

Mike P.

[Vanny]

It's deffinately a BX one, thats clear just by looking at it (405 loom is very over complicated with various multiplug connectors (9 and 7 way brown) which no BX uses!

I have obviously asked Gary and he's told me that its from an E-reg 16v. It's obviously ment to go through the bulk head by the battery which is likely to be impossible for me to route as i have sooooo much stuff going through there already (inc AC wiring and power to the boot).

I've also been looking into it further and it seems that aircon 16v's have a totally different loom again which swithces the AC off on full throttle and on over heating, and raises the idle with the AC on. Shoulnd't be too hard to add the wiring, but might be a problem if it requires a different ECU


Oh what a learning curve! But by my reckoning this loom is MUCH better for a 205 conversion as you dont have to go miles and miles round the car, just hope i can find someone willing to swap!

[jayw]

My G plate has it running through behind the battery, round the engine bay to the relays on the driver side wing.

The H plate comes in through the wing to the big round multiplug on the riser by the engine mount and then all over the place.

Still, the latter is a lot easier for removing the engine & box as it's just 1 main connection for the wiring (though i've not noticed where the relays are relocated to).

No idea why Citroen went to so much trouble to change between the 2 looms, especially as the BX was within a couple of years of death.

[Vanny]

Jay, the relays are relocated to the void under the drivers seat (right next to the ECU, and obviously much closer to the fuel pump which rather makes sence).

I suspect the change was because or EU regulations meaning the need for a CAT and lower emisions which also meant a move to a different ECU with knock sensors lambda sensors etc the later ECU has a three row ecu and extra wires (but not as many wires as there are holes, the extra pin outs from the ECU are for extra funtions including two more injectors). The extrawires probably started to make going a different route a little easier as the hole behind the bulk head was starting to get rather full (especially with aircon), im sure other european factors will have had soemhting to do with it (wires for the head light washers for example) and i'f they where trying to just fit out shells they had then i guess its a nice easy add on to just throw a longer loom that fits easily enough!

[jayw]

Does that mean the one's with the big single connector have a 3-row ECU or did i read that wrong?

I've never paid that much attention to little details like that on the H plate as it's always been reliable and i've never needed to take it apart!

[martyn]

Mines a late '90 a/c model and has the large round connector by the engine mount and a 3 row ecu no. 0261 200 354.
Vanny is the second relay under the seat for the injectors?

[Vanny]

BX GTi 1.9 litre 16 Valve 87-89 ML4.1 0261200119 - 2 row
BX GTi 1.9 litre 16 Valve 89-90 ML4.1 0261200140
BX GTi 1.9 litre 16 Valve 90-93 M1.3 0261200354 - 3 row


thats how the ECU's line up and as you can see the ECU number changed for a little while to the 140 which i think is when the long loom came in. However, i believe that some of these had two row and some had three row.

The M1.3 only came in a long loom and all of them had a round connector to the engine part of the loom, these can also take Lambda sensors and knock sensors but had to have an AFM (other option would have been to have TPS and MAPI sensors)

The second phase of the ML4.1 had round connectors and square connectors as best i know, so there is no guarantee that if you have a round connector in the engine bay that you have either version of Motronic (ML4.1 or M1.3).

For the later ML4.1 and i think the M1.3 (though i have never seen the M1.3 but i assume this is what Adrian had) both the injection and fuel pump relays are located by the ECU under the seat, and are the same relays as the earlier short looms (just not in the engine bay, you'd think have the injection relay in the engine bay and the pump relay in the cab but perhaps they are setup in the same location to cancel out differences in heat?

[Gary C]

Answer. JW shortened it

Spoke to him earlier and he believes this is our original loom which was used when the ecu was moved to the passenger side; for ease of access (plus some weight saving); it was bolted below the fuse box. Should save several kilos in weight for the old BX to drag about.

Apologies for any confusion but one loom looks much like another to me.

Regards

The Nut behind the wheel.

[Toddman]

Answer. JW shortened it

Spoke to him earlier and he believes this is our original loom which was used when the ecu was moved to the passenger side; for ease of access (plus some weight saving); it was bolted below the fuse box. Should save several kilos in weight for the old BX to drag about.

Apologies for any confusion but one loom looks much like another to me.

Regards

The Nut behind the wheel.

Seems I was about right then

Cheers
Luke