V6-12V - ECU wiring

[GMC]

I have just stripped my Alfa V6 - 12V (1988) model tonight. To made life easy for me, can some tell me the wires that I need to keep for to the ECU and the ones needed to start the engine again !

[roger001]

John rutter is the chap to speak to on this, basicly you keep the ECU/injector loom intact (although some have cut it and shortened it _ brave) it conects back to the engine as it came off, the conection to the cars harness is 4 wires all in and near to one of the plugs, one is fuel pump power white/pink, one is tacho signal white/brown, the third from the plug is coil supply green/black the fourth conection is a bunle of red wires which are a live feed from the battery.

[Stratos]

Gerry,

Roger has pretty-well told you everything.

Keep the whole engine loom intact. Find the wires that Roger mentioned, and connect them to the relevant wires from your existing loom - turn the key, and VROOOM!!!!

I know it sounds too simple, but it is!

[GMC]

That all makes sence but is there any wire connected to a light on the dash the tell the ECU that all is well ? I recently wire an ECU from an Opel car and without the ECU been able to turn off a light on the dash it would run on "safe mode" in other words it drank petrol. In the Opels case the bulb wasconnected to live and the ECU supply the earth (opposite to what you /(me) might think)

[roger001]

nope!

There may be one but if there is it does not matter, it run just fine without.

[GMC]

Yes it will run. but have you done a plug cut ? the reason why I am concerned is that both Opel and Alfa both use the Motronic ECU and there is a big difference in fuel consumption and crispness of the eninge :confused:

[Stratos]

Gerry,

Haven't heard of anything like this light on the dash situation with respect to the Alfa V6.

I don't recall disconnecting anything like this when I've taken V6 engines out of my 164s.

[rutthenut]

Not seen any form if ecu indicator light in the wiring diagram of the engine loom. Certainly haven't needed to fit one in any way.

I don't have the wiring colour codes or anything else at present, but the info already posted indicates that it is fairly simple to plumb in the ecu loom. I think that there is/was a single eight-way plug and that you then just make a few of the connections from there to the kit loom. If you haven't found out from other sources, I'll try to sort out the info in the next few days if you still need it.

Related to another question, the ecu does control the fuel pump operation, but you do not have to use this method if you don't want to. The pump is only turned on by the ecu when the engine is rotating, as determined by the crank sensor. This can lead to a few headaches when first debugging the system if anything is wrong, so you may want to set up a manual power supply to the pump just to prime the system. Then again, the oil system needs to be primed too, so you don't want the engine to fire up immediately when your first turn it over (another topic, I guess).

If you don't use the ecu to switch the fuel pump, do make sure that it does turn off when the ignition is switched off and that it will not run continuously. I use the ecu to control mine, it's not at all a problem once everything is known to work.

Another thought about warning lights and the Alfa V6, which is a common 'gotcha' - the oil pressure warning lamp on this car works in a fail-safe warning mode, i.e. in reverse! I think this was explained in the Yahoo Group, but if you just wire up the lamp to the standard switch, it will be extinguished when the engine is not running and will light when the oil pressure is ok.

This does mean that if the switch fails, the lamp comes on. Whereas I had a problem once with a switch that failed coincidentally with an oil leak that resulted in loss of pressure. The lamp didn't come up on the dash and the first I knew was that the engine temperature shot right up and when I slowed down from speed I could then hear the big-ends rattling away. Very unlucky for both failures to happen at once, but it wrecked that engine. This wasn't on an Italian car, by the way.

You have two options with the oil pressure warning lamp. Either change the Alfa switch for a more 'normal' switch that works in the simpler fashion, or fit an improved wiring setup to drive the warning lamp. I guess a changeover relay is what you use here, although I'm sure there are other methods available using diodes and things. I've not done this though, just used a standard type of high-pressure oil switch and left the wiring alone.

Still, it's nice to know about this rather than having a panic when first running the Alfa engine in your kit and thinking it has no oil pressure - it may just be the reversed operation of the switch...

[CorseChris]

Gerry,

The ECU on the Alfa does have a facility for a diagnostic lamp/switch arrangement (I fitted one to my donor car just so I could be sure it was OK - the later cars have it as standard). It is simply a diagnostic item and has no effect on the normal running of the engine.

If you are really keen, I can give you the wiring info.

Personally, I would be happier to let the ECU continue to manage the fuel pump. Nice to know that if the engine does stop (say, in an accident), the pump stops as well.

Just connect it up as suggested and enjoy!

Chris

[rutthenut]

Originally posted by CorseChris
The ECU on the Alfa does have a facility for a diagnostic lamp/switch arrangement (I fitted one to my donor car just so I could be sure it was OK - the later cars have it as standard). It is simply a diagnostic item and has no effect on the normal running of the engine.

I suppose this connects up to the 'unused' connector from the engine loom which I recall has a four or five way plug of some sort. This is separate to the main feed/switch connector that needs to be joined up with the kit loom.

Wouldn't hurt to know a bit more about what can be run from this additional 'diagnostic' connector. I always assumed it was for other equipment to be plugged in to the system. Hadn't thought about it being a bit more simple, perhaps providing certain voltage levels or signals as handled by the ecu itself.

[CorseChris]

John,

That's the one. All you need is a push-to-make momentary switch, and a small lamp that will accept 12V. With this, you can initiate the diagnotic readout and some self-test routines (as detailed on the 164 cardisk). US spec cars all seem to have this built in with a switch on the column and a lamp on the dash.

I also experimented with the possibility of fitting a lambda probe and working the car closed-loop but didn't get very far as I suspect the ECU lacks the necessary code in the firmware. It seemed to have all the appropriate hardware fitted though, as the lambda input pin went all the way from the edge connector, through the signal conditioning and on to what I assumed to be the A/D converter.

I'll dig out my scribblings and post a jpeg.

Chris

[David May]

I've been playing a bit with the diagnostic tester interface. Up until 1993 it was used exclusively to connect to the official AR workshop tester (using the standard ISO-8 3-wire interface K+L+GND) and a serial code to interrogate the ECU error memory.
From 1994 onwards the K-line was routed via the immobiliser module (where fitted) to run the encoded handshaking during key-on while still allowing diagnostic testing.
The ISO-8 method has now been superceded (for most markets)
by the (USA based) OBD/KW2000 protocol, which allows almost anybodys tester to talk to the error memory of any ECU.

If you know all the codes involved (I don't!) you should be able to read all the internal parameters and also activate the various drivers (as used for EOL testing.)

Dave M

[CorseChris]

To finish off what I was waffling about, if you want to add a simple diagnostic lamp & switch arrangement, try the following. No guarantee it's going to work on your particular version of ECU, but it's worth a go.

Parts required. Small 12v lamp & holder (ideally, maximum of 1.2W). Push to make, non-latching switch.

Locate the 4 (or possibly 5) way connector in the ECU loom that is near to the main ECU connector. It should have the following colours of wire going to it - White (+12v with ign on), Black (ground), light blue/yellow (ECU pin 4 and main diagnosic plug), light blue/red (ECU pin 17).

Connect the parts as follows;

Lamp - white one side, light blue/red the other
Switch - black one side, light blue/yellow the other

Once done, switch on the ignition (but don't start the engine) and the lamp should stay off. Press and hold the button until the lamp flashes. Release the button and it should then flash the currently stored error code. A sequence of 4 lots of 4 short flashes means no problems. For a full description of what's what, see the 164 data CD. It's possible to initiate a few basic checks with this switch as well (idle speed actuator, injector test plus some others I forget).

Trust this is of some small interest to someone out there. It's not as useful as the full blown diagnostics that David is talking about, but at least it's achievable by most of us and will help in diagnosing the more common problems. This lamp and switch sems to have been fitted to all the US cars, but I have never seen one on a UK spec car. The later versions of Motronic have a more sophisticated diagnostic setup which can be accessed by switching on the ignition (NOT starting the engine), then pumping the throttle pedal 5 times in quick succession. This then gives access to the same system of error flash codes via the injection trouble light that should be on the dash.

[GMC]

Help!
Using the wires that were on a small grey seven pin plug that was connected near the bulk head (Alfa ) I have connected the white / pink wire to supply the fuel pump with power, I connected the green / black to ignition switch to supply the ECU with power, and connected the red wires to the battery. I did not connect the white / brown as I do not have a six cylinder tacho yet.
The engine will not start. No spark.
Must I connect the White / brown ?? onto the back of the rev counter ?
Have I connected the green / black correctly ?

The wires that are left over from the seven pin plug are, Pink -
Green / white - Yellow / Grey - Yellow / Green, these are also not connected :confused:

Help please, I just want to get started

[GMC]

All sorted, the missing part was the pink wire, when I got an Alfa wiring diagram from a dealer today I noticed the pink wire must be connected. Did someone forget to mention this the one of the above threads ?

[chris.richard]

It's a long time since this thread was aired, but it's the appropriate place for this query.

There are a number of redundant wires in the ECU loom; is it OK just to remove them? Things like connections to aircon, automatic transmissions etc. If I cut the wires and insulate the ends, or remove the pins from the ECU connector, will it still work? (It's not something I can hit with a hammer or put a mole wrench on, so I need to ask!);)

[Stratos]

Not the Automatic!!!!!

I've been told that if that gets disconnected, the engine stops. Never tried removing it on mine, so can't confirm 100%.

[rutthenut]

Yes, you can remove the unused wires and pins from the ecu loom if you want. Probably more effort than it is worth though!

I went through this process when first fitting my V6 engine, but partly because the loom itself was damaged, so I removed redundant wires and pins, got rid of the huge bulkhead grommet and shortened the loom overall. And even got it working in the end!!!

But the automatic 'sense' wire needs to be checked out first, as per Dave's warning. I cannot remember know if it needs to be open, closed to earth, or closed to supply. I have no idea what will happen if it is not connected (or open) as required, so it may well cause the engine to stop - might be one of those safety things that prevent the engine being started if not in park?

I'm afraid the wiring diagram I used does not copy at all well, so would not be any use to you. Perhaps you've already got one?

[chris.richard]

I'm workingfrom the cardisc one, whichis fine; only a problem to print for some reason.(Single pages print OK, the double page spreads are spat out as blank sheets)
It does seem odd that a wire that doesn't connect to anything should cause a problem when it is removed. (If it was an aerial, I could understand it)

Chris

[roger001]

one of the connector blocks near the ECU has two wires feeing it, on an automatic these are left "disconnected" but for a manual the have to be connected by a small link, the reson for this I dont know, I guess it is a way of telling the ECU to think in auto or manual mode.

[Stratos]

Originally posted by roger001
one of the connector blocks near the ECU has two wires feeing it, on an automatic these are left "disconnected" but for a manual the have to be connected by a small link, the reson for this I dont know, I guess it is a way of telling the ECU to think in auto or manual mode.

Roger,

That's the one I was talking about, but you've explained it much better than me.

[kens]

I recently converted from an automatic. There is an I10 relay that you will probably omit anyway. The automatic no-start wire runs from the transmission to the I10 relay, for starting the gray wire must be grounded.

[chris.richard]

Doesn't tally with my wiring loom - the connection to the CAE (electronic automatic transmission) has 4 wires Pink/yellow; grey/black; yellow ; white. In the wiring diagram they show no alternative connection for a manual.
Oh no, I've just thought - there aren't different ECUs for manual and automatic are there/:eek: :( :confused: :mad:
Straight to the parts disc. Exit stage left, panicking!

[chris.richard]

Same part numbers! Phew!:cool:

[rutthenut]

Originally posted by chris.richard
Doesn't tally with my wiring loom - the connection to the CAE (electronic automatic transmission) has 4 wires Pink/yellow; grey/black; yellow ; white. In the wiring diagram they show no alternative connection for a manual.

From what I recall, the auto/manual connection is on a separate 'tail' from the loom, possibly near to the diagnostics connector.

It isn't run through the main connector for the engine management loom, so the wires listed above will be ok. It's somewhere else within the engine bay and should be easy to sort out when you find it!

[roger001]

The auto/manual selector i have described is on a 12v wiring harness - i'm sorry to say that I'm sure it is totally different on a 24v

[richard hall]

can a 164 12v loom be fitted to a 24v engine,also are the starter and alternator the same? ecu etc... i have a 12v car to strip and have been offered a 24v lump without electrics!

[roger001]

the simple answer is - no! lots of differences the least being the ECU

[Martin K]

All sorted, the missing part was the pink wire, when I got an Alfa wiring diagram from a dealer today I noticed the pink wire must be connected. Did someone forget to mention this the one of the above threads ?

For clarity, what must the pink wire be connected to?

[John]

The pink wire should be an ignition fused +ve and feeds into the fuel pump relay. When the fuel pump relay is energised this then feeds the fuel pump through the pink/white wire.
At the fuel pump relay the pink wire loops off to energize the Motronic relay (usually has a red stripe on top to identify it). The Motronic relay in turn then provides battery +ve back to the fuel pump relay to actually energize it (switch it on that is).
The Motronic relay also provides battery +ve voltage to the idle valve and the injectors.

I'd better qualify my interpretation of the wiring diagram by saying don't take this as gospel until Mick's engine fires up. It was me who altered his engine loom!!

[Swamprat33]

Ahhh, the cats out of the bag now John.

Alfa V3 indeed :p

Cheers
Tim