Alfa V6 wiring

[Andrew Way]

I'm just about to start making my own loom for my V6 (standard 12v). Does anyone know of any good newsletter articles I should read? John Rutter wrote some wise words in #36 (p7-10). I'm sure I've seen a list of which wires go where from the ECU - but I can't find it!

Thanks,
Andrew.

[guy mayers]

Erm...... what's wrong with the original loom? If you need a copy of Alfas' wiring loom drop me a line and I'll send you one......if I can find it!
Cheers
guy

[roger001]

I've just finished making up the loom necessary for a DTA ECU.

Vehicle wiring product supplied all the necessary components/plugs etc.

However cant see the point of doing this if you are using the standard ECU. Apart from shortening it to get rid of exccesive length. Or do you have "a cunning plan"

[chris.richard]

If you'er shortening the standard loom, watch out for the cables that are shielded by foil wrapping. There are 3 or 4 on the 24v, they're a bit harder to cut & shut satisfactorily. The wiring diagram will alert you to these; guess who found out the hard way?:(

[David May]

Which hard way was that then? Could not get the crank sensor to read again or what??

Dave May

(Nothing nasty meant, I'm just interested in what can, and does go wrong...)

[chris.richard]

I don't know the final outcome yet, because the engine hasn't been run until the cooling circuits are finished ( which is held up by the de-rusting of the front end). I was merrily (subtle christmas reference) cutting and soldering cables, and found one a bit harder to cut, and said b***er when I looked at what I'd cut, with the tinfoil all unravelled. I re-shielded the spliced cable, but the shielding is relying on touch contact for continuity. The word was "bother", by the way!

[Andrew Way]

what's wrong with the original loom?

I just wanted to do my own loom so that I could route it exactly as I want to. The only screened cable is the one for the crank sensor. Luckily I have a very good (free;)) source of wiring components so I'm going to make my own loom.

[David May]

My Q4 24V had loads of screened wires (crank sensor, cam sensor, coil signals, 2 knock sensors, 2 Lambda sensors) which I diligently made with screened (Teflon) cables when I made up my rear loom. I can understand it for the unamplified crank sensor but it looked a bit excessive for the rest - they must have had some problems on the top-model 164s to spend their money on screening, nobody else bothers!

I'm amazed just how many people have the skill and patience to do a full rewire - it's a rotten job until the loom tape covers it all up!. Hats off to you all!

Dave May

[Arthur]

I did mine, I looked at the huge nylon plug thing, and said "that'll have to go".
Daftest thing I've ever said.
So, when I finished splicing cables (only the one shielded in my loom, lads ) I did the crank sensor one. Simply stripped back enough outer to do (twist and solder) the core and shrink-wrap it, then slipped over (remember it was cut at this stage) a length of braided copper cut from TV aerial coax cable. Made sure of a generous overlap with the foil wrap, and just shrink-wrapped it - runs fine, no probs at all.
If you are paranoid, solder a spare black core to this screen and earth wherever you feel like. But it's truly not necessary.

Speaking of the loom wiring diagram, remember there are a couple of bogies lurking there. There's the "no idea what its for" relay, just leave the loom as it is, then there's the parking brake interlock for the auto g'box, which needs a link fitting permanently, or you'll never get the bugger to crank. (actually, should you wish to run this out to a single blade-fuse holder, its probably the cheapest theft insurance you can do!).

Oh yes, its worth paying the dosh when its done to get the ECU checked via the Motronic and Alfa diagnostic ports - the ECU may well be carrying fault messages from the donor vehicle, and unless cleared may cause you untold trouble (like can't get it legal at idle cos its running a "get you home" strategy for no good reason at all).

All the best
Arthur.

[chris.richard]

Originally posted by Arthur
[B, then there's the parking brake interlock for the auto g'box, which needs a link fitting permanently, or you'll never get the bugger to crank. (actually, should you wish to run this out to a single blade-fuse holder, its probably the cheapest theft insurance you can do!).
[/B]

Arthur, you're posting some relly useful stuff today!
Is the autobox interlock a link to +12v or to ground?

[Arthur]

Chris,

Thanks for the vote of confidence - in me day job as Chief Engineer for BP Shipping on Tankers, with a side interest in short red things with unfeasibly large engines, I must have learned something worthwhile. But as with all things, I believe whole-heartedly in Carroll Smith's "end-user responsibility" clause. Just cos I've said it doesn't absolve anyone else of the responsibility to gauge the advice and its worth before applying it. I try to get my guys (in the day job) to look at WHY things are good ideas first, and with luck that translates to a more forward-thinking approach, generating lots more good ideas.
Passing on the best of the solutions I've found to date is by no means "the only way". If there's one way, there will be a dozen ways - but all I can say is "here's one that worked for me".

I regret, for instance, using those rivnut things in Aluminium, with Stainless dome-head fasteners. Looks good, but the aluminium still corrodes, and I can't get the damn dome heads out. What I should do - and am in the process of doing - is drilling them out, re-rivetting the rivnuts, setting stainless stud bar with Loctite, and using half or full-height Stainless nylocks on the stainless studs. Don't care that the stud will never come out; I can at least get the nuts off when I need to.

It must be 5 years since I finished wiring the damn thing; since I'd have to go back to the Motronic wiring diagram, or alternatively check what's fitted and report back by wire colour / terminal designation, I'm using the "I've just moved house and can't find anything" gambit.
I seem to recall that the loom came with a chatty tatty relay still attached to a relay base on a flying length of loom. Not part of the ECU, so God knows where it went on the 164. Never interested enough to find out (not to be confused with the two "Motronic Relays", on their own base, which of course you still need). On closer inspection, the "change-over contacts" in this relay were soldered solid, so there's a clue for the observant. (I assume this soldered relay would be the only difference between an Auto box and a Mnaual box). Just pull the relay, chuck it in the the bin with the growing pile of other "what the hell was that" bits, and solid-link the terminals together (there are only two, I think).

I'd be very wary of doing an ECU loom - when you look at the schematic, you start to realise the cunning in the design, esp. with reference to the loom internal earth links. Some of these, I seem to recall, are used as link-outs for unused ECU functions, as well as being earths, and I'd hate to guess whether or not any of these paths had pre-planned impedences read by the ECU. Things with chips in need treating with extreme respect, unless you understand them, and I speak as one who uses this kit all the time in the day job, and still don't have the confidence to mess with it.

Mind you, :D I did all my own loom drawings, layed it all up myself, and it worked first cat out out of the bag. Every lamp seperately fused; intruder alarm cabling all in, lamps and flash all worked first time (snuk snuk) etc.
Apart from the Motronic loom, which I used as presented apart from removing the nylon plug, and about 3 feet of loom altogether.
Only two things have gone wrong with it in 4 years legal (11500 miles). The flasher can (used the old tin can job as the simplest fit, and will not go obsolete with updated road car models) has failed twice; but I don't have to get the SVA flash speed checked ever again, so its now on a hazard light flash can.
Second was an intermittent starting problem. Sometimes no crank, sometimes fine. Drove me to distraction.
Good one, this - traced it to the Exide battery. The terminals were at root flat lugs. Exide, in their wisdom, had popped adapters over the tabs to make it tapered pillars. The contact between the lugs and pillar adapters was dire.
All it cost me was another new battery, with the ledges planed off, etc to fit the tray.

Oh yes, I can also remember one other bugger - should you use the Alfa 164 handbrake actuator, the parking light switch is a**e about face. Its open with the handbrake on. (for the Motronic auto box interlock, of course). So you'll need to plan 1 extra relay if you want a parking brake light on your dash.

All the best, Chris - if you do need any ECU drawings, I'm sure I'd be able to dig 'em out, but at the end of the day, they were just a photocopy run off on Hugh Carson's fax!
Same's true for the full car loom, but I've tried to post scans on the website before, but they are too big, and I get chucked off.

Regards
Arthur.

[Andrew Way]

Originally posted by chris.richard

Is the autobox interlock a link to +12v or to ground?

From memory you need to ground it (but I may need to check that!). I did my own (prototype) engine wiring loom last month and the engine started first time...... I wasn't expecting that! There are lots of connections which can be ignored or grounded if all you want is a simple system; from the 35 way plug 23 pins are used, 5 of which are grounded. You then have the choice of using the ECU status light, ECU interrogation button, lambda sensor, Alfa diagnostic port etc. Only two relays are required, one of which is for the fuel pump and the other handles the high current drain of the injectors and coil (amongst other things).

As mentioned else where on the forum, you do also need a relay to invert the oil pressure warning light:eek:

Andrew.

[CorseChris]

Pretty sure that the WTF? relay is the CAT coding relay. Seems to be used to differentiate between CAT (and therefore Lambda probe) equipped models and non-CAT ones. That it was a fixed short on Arthur's loom suggests I might be thinking about the right thing here 'cos when I first saw the wiring, I couldn't see any sense to putting a normal relay in as a coding device. This would be an important item if you went from having a lambda on the donor and none on the kit of course..... 'tother way around less of an issue.

[Arthur]

I have in front of me the chatty Fax copy of the motronic loom wiring diagram for the 12V 3-litre.

As far as I can find out, the 12V was never fitted with Lambda control, so there's one thing less to worry about. No idea about the 24V motors.
Should this ever be relevant, the motor I have was put together, after much badgering by me as the build progressed, by Mike Buckler of Rusper Alfa romeo, from bits he had lying around at the time.
I believe I have a Cloverleaf motor, at least its doing about 209 BHP on Peter Hignett's rollers at Astmoor Garage, Runcorn (another very fine contact for those of you close enough to get to Geoff Turton's shop in Widnes) (Peter incidentally does race and rally car preparation and support, as well as being a commercial garage with specialist Bosch diagnostic equipment and full MOT gear).
So I guess its got the right compression ratio, which I think was the only difference in the engine, but whether I have the right AFM is moot - I didn't know there was a difference til it came up on the Forum recently. I also think I have a standard rather than Cloverleaf short diff, but I actually like that on the road, and to be honest, first and second would be awfully short with a shorter diff.

Anyhow, back to the ECU drawings, labelled Motronic 3.0 Diagram A.
S12A is the fuel pump relay. S12B is the Motronic relay. You need both of these as fitted. Both of those are straight ON/OFF relays, but whether Type A or Type B I don't know. Supply on terminal 30, load on 87, and coil on 84 and 85 for those who need to know which relay type.
The one you need a solid link for is S25, a 2-pin female plug, which used to be the link for the Auto Transmission.
The Alfa test port is a 3-pin female, T1.
The relay Q22, on 5-pin base C184 (I think, could be 154 or 164, this copy is not great) is the electromagnetic coupling relay for the AirCon (I believe it steps up the idle speed a touch to maintain battery charging with the AC on at idle - wish I'd known this earlier; when I first cranked I had an idle of 600 rpm, and the alternator would not charge. But its possible to pick this up to about 800 by tweaking the throttle body back stop, provided you remember to reset the throttle pot idle click stop as well. Linking the idle speed boost for AC may well have saved me doing this). The cable colours are Green/White and Grey/Yellow to this baby.
The WTF? relay, terminals solid-soldered on my loom, is on plug S30. The hand-written note says "Motronic Central.......nt switch connector". Or it could be "Motronic cont..l...n switch connector". Whoopee. You don't need this, whatever it was, so in the bin it goes leaving the relay base hanging free. (Have tried it linked out and open terminals - not a scrap of difference either way). It actually takes the ECU multi-pin S11 Terminal 10 to earth when linked, whatever that means.
The Motronic diagnostic port is a 5-pin female plug T2.
The battery live goes into a 4-pin female connector, with only two terminals in use. One is green/black, into terminal 2, can't read or remember the other. The battery live goes into terminal 3. The juice comes out of terminal 2 on ignition switch, then to the fuse, the out of the fuse to the pink wire heading for Terminal one on connector G154.

Best bet is to get the ignition switch and column from the donor 164 if you can (or if you need, as per the CorseI). Then just extend the cores as required to fit the car. Oh yes, if you do, get the ignition key as well, and copy it fist job).

You probably won't need the Alfa Tacho signal on the brown/white wire from G154, but since it reads the coil as per all electronic tacho's, its there if you want it.
The fuel pump supply is on the pink/white wire from G154 terminal 8.

I think that's it for the Motronic stuff.

AOB
Someone somewhere mentioned inverting the oil pressure switch for dash warning light - not necessary if you replace the standard switch with a high-pressure aftermarket device. (Beware, when hot, you will see barely 1 bar pressure, and since aftermarket HP switches tend to be about 25psi, you'll get used to the big amber flashing light at idle).
The Alfa dipstick has a level monitoring device - I could not see how this worked, so its gone - just cut the wires off flush and forgot about it.
The water temperature sensor may come on a variety of threads - possibly M16, possibly M18 depending on your luck, so matching threads may be a sod when you go aftermarket sensor, as you probably will, to match the gauge.
Some of the aftermarket gauges have an earth terminal, some don't, (case bleeds to eath through the mounting threads) and depending how lucky you are, the case may or may not have a decent earth, so be prepared not to believe what they tell you til you've run a flying earth to the casing anyway to double-check. If the indicated value jumps about at all as you apply the external earth, you will need a permanent one fitting.
The speedo as Alfa - once again, I couldn't tell what sort of output it had for gauge matching, and in any case the accuracy would be moot depending on gears ratio and wheel size, so I took this off and chucked it away. BEWARE - if you decide that the drive gear is also redundant, and remove it, it will most likely fall in the final drive gearcase, which is a real "close eyes, raise head heavenward, and swear" kind of moment. Especially when you find the casing will release but not actually come out of the car for cleaning and re-sealing. (although I believe the entire final drive case will come out, if you haven't already done the driveshafts). (This is just the CorseI, you understand).
Anything else - oh yes, electronic speedo. Gave me much grief. I fitted it (VDO gauge with inductive pulse sensor) with the signal wire sheathed (Computer small ethernet cable is just made for this). Didn't work worth a damn. Made sure I had just one end of the sheathing earthed - still no good (earthing BOTH ends of the sheathing can set up circulating currents in the sheathing, which you do not want - don't do it). Took the fore/aft loom out, separated the core into its own sheath, no difference. Took the junctions out of the cable, so now direct from speedo to sensor - no difference. Finall ran the gauge earth as a sheathed cable from the sensor to the gauge in a seperate sheath external to the main loom - much better, but still prone to losing signal. Finally played with the sensor air gap. Started at about a fag paper thickness - gradually eased the gap up (you need a good spike - running too close a gap can cause interference between pulses sufficient to confuse the speedo reader. Opening the airgap gives a lower spike, but loses the interference, so the speedo sees a much cleaner signal). I'm currently running a couple of mil gap, and it probably needs to be more yet - its stable to abou 70 mph indicated, on a 6 pulse per rev signal (reading the bolt heads on the inboard rear driveshaft coupling) but tends to lose it and waves around much faster than this. Some of this is vibration induced - on the SVA rollers it was dead stable to flat whack. God knows what to do now - its on the Mark 4 bracket, screened both cables, no connectors in the line, earthed wherever I can - still the same.

All the best, sorry it was so long, but there you go.
Arthur.

[David May]

Well done Arthur - you've managed to dig yourself out of all of the pitfalls!
The speedo sensor problem is probably due to using an active sensor (like the original AR.) They require about 5mA in the off state and >10mA in the on-state so are not simple on/off switches. They ideally require a current source and current threshold type of instrument input but can be fiddled to work by applying a variable pullup (variable trimmer to +12V or +5V).

On my Q4 ECU the A/C input only speeds the tickover from 750 to 820rpm but does help the alternator charge and water pump when cooling off after a race.

I'm not sure about using driveshaft coupling bolts for a pickup. There's probably too much movement there to assure a gap within 0,5mm and the bolt heads are very narrow, giving tiny pulses. The standard electronic pickup (later cars) works well, apart from the strange drive ratios.


Dave May

[CorseChris]

Originally posted by Arthur


As far as I can find out, the 12V was never fitted with Lambda control, so there's one thing less to worry about.

US market cars did AFAIK, but we aren't likely to see many of those this side of the pond... it's just more wires to worry about.

[roger001]

differences between cloverleaf and standard 12v motor are

1. higher compression 10:1
2. different cams
3. different ECU
4. different AFM, the outlet of a cloverleaf AFM is approx 80mm dia as oppossed to approc 65mm on a standard AFM

I will take a camera to the barn text time I'm up and take a piccie of both for comparison. ditto the ECUs. ( I have a pair of both standard and cloverleaf spare)

[rutthenut]

OK then, I have/had a wiring diagram for the Motronic system engine loom on the 12v engine, and managed to shorten/adapt the damaged loom in my car with no problems in the past.

Since it looks like I'm now (hopefully) going the 24v route this time, does anyone have wiring diagrams for that system? I don't plan to modify the loom, but would like to understand it. And does it need a Lambda sensor on the exhaust?

If not wiring diagrams, how about the connections between Hawk dash/power loom and the 24v engine loom? Presumably only a few wires again, with permanent live, switched live, tacho feed (bet that's not going to work on a standard Fiat gauge), and maybe a relay/switch feed for the fuel pump?

On the older setup, this was an eight-way connector of some sort, and not all connections were used.

How is the 24v system connected up?

[David May]

I too upgraded from a 12V (turbo) to a 24V Q4 (4WD) and there was not one wire or connector in common - I ended up making yet another full rear wiring loom. AFAIK all 24V were at least Euro1 emisisons (lambda) and mine was USA specs with 2 lambdas, EGR and evapoaration valves, immobiliser, 4WD - load of wires! Luckily it still produces full power without going into limp-home mode with some missing.
You'll need to know the origins of the motor to get the right circuit diagrams - and there are loads of optionals to confuse things further.

[rutthenut]

Not that I want to pay fifty quid and wait weeks for delivery, but I wonder if this book would be of any use for 164 engine transplants?

http://www.amazon.co.uk/exec/obidos/ASIN/1859605583/qid%3D1109013388/026-5334021-5350864

[shaun]

Funny you should mention this company. I placed two orders with them in December since I would be in the uk for Jan.

Order one was possibly a hoax and I should get a credit card refund on the secondhand book I did not recieve - how long that will take is anyones guess.

Order two is still an ongoing saga, that is over 8 weeks from the initial order and a promised despatch in the next 3 to 5 weeks.

I will never agian use this company.

[rutthenut]

Don't blame you for holding that opinion, but for me the convenience is still sometimes worthwhile.

But I only tend to order books from Amazon if they are listed as 'delivery within 24 hours'. If they list anything longer than that, it is usually going to be an unknown time.

I have placed orders for 24-hr delivery before, got the confirmation, then shortly after got notification that it will be some days before delivery. In that case, I simply cancel the order there and then - I've usually chosen to pay for prompt delivery and want to know I am going to get the book. If they can't assure me of that, I won't use them!