Greg_S S2 Coupe 20+ years going strong

[Greg_S]

I had 5 mins to take another look this afternoon and started with the fuel pump relay and removed the cover. It isn't operating on the ignition to activate it. When manually closing the after run pump amongst other component Spring it o life, but still won't start. It appears the small terminal has 12v supplied to it, I'll have a check through the wiring diagrams this week to try and work out what to look at next. Also setup a couple of mouse traps just incase

[Greg_S]

I've been going through the schematics again this morning. http://www.s2central.net/S2_Schematics/B/B73.PDF

I'm getting a bit screen blind though. Can anyone tell me where bus 15 is fed from and where it connects. I'd like to avoid taking the fuse box out to check underneath as I'm more likely to disturb more connections in doing so. I'll mark down what voltages and states I'm getting on the fuel pump relay next.

I may have answered my own question. The ignition switch connects to track 15 (A2) up from the dash wiring loom. http://www.s2central.net/S2_Schematics/D/D44-07.pdf

So this is where I should focus some more effort to verify the connectivity

[Greg_S]

Finally had an opportunity to check the s2 out again and been retracing steps today. So far tested relays 1,4,5,7,8,10 as we have been working through. I've traced back through to the fuel pump relay which the relay operates fine, however the Ecu isn't switching it on.

I'm trying to check how the Ecu is powered as it doesn't appear to have a feed. Which circuits provide supply to the Ecu?

[Greg_S]

Found ABY pin out on mikes site here http://www.s2-audi.co.uk/tech_articles/motronic/ecu.htm permanent 12v to pin 18 on Ecu is good. As is the gnd's to pins 10,14,19,24,30

What isn't buzzing out is the 12v switched ignition live to pin 27 on the Ecu. From the wiring diagrams this connects to 69 on the wiring diagrams. Any idea where that is?

[Nace20]

i have AAN electric plan here and it looks like it is same fuse that is for coils

[Shoto]

In motor wiring there are relays 205 and 364?

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[newsh]

Are you 100% sure the timing is correct? The ECU won't energise the FP relay if it's not.

And is the timing pin present on the flywheel?

[Shoto]

If in motor wiring is 205 and 364 relays, 205 relay cuts off that timing pin on flywheel. I mean if motor wiring is with anti theft and immo version. So you must take off 205 relay.

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[Mikes2]

That's a black wire to fuse 32

on this diagram

http://s2-audi.co.uk/workshop/schematics/motronic_aby/page7.png

[Greg_S]

First of all, thanks for all of the replies.

i have AAN electric plan here and it looks like it is same fuse that is for coils

Yes I think thats correct, also based on Mikes link to the wiring diagram

Are you 100% sure the timing is correct? The ECU won't energise the FP relay if it's not.

And is the timing pin present on the flywheel?

I'll see if I can check the timing pin, however I hadn't considered this as an option. The last time I used the S2 i drove home parked up in garage as I normally would and was running fine. Then the next time I came to use about a week later I couldn't get her to start. I've been unable to get the ECU to respond to vagcom either so thats where I started to suspect an issue with power to the ECU, will try the blink codes incase it is a faulty vagcom cable I have which is one of the ebay generic jobs.

If in motor wiring is 205 and 364 relays, 205 relay cuts off that timing pin on flywheel. I mean if motor wiring is with anti theft and immo version. So you must take off 205 relay.

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Just been out and checked for these two relays on the S2 but didnt locate them in the fuse box. Are the one of those under the dash?

i've attached a pic of the fuse board for reference

That's a black wire to fuse 32

on this diagram

http://s2-audi.co.uk/workshop/schema..._aby/page7.png

Mike, That was what I was expecting too. I took the cover off of the ECU loom to check the wire connecting to pin 27. It is sw/gr (black/grey) if I got the colours correct.

After running through and retracing steps today im back to looking at an issue between the ignition and ECU power. In addition to not starting the auto check is now flagging up the oil sensor light too when ignition switch is on and immob disabled. I suspect this is a sympton of the other issues. Also the electric windows wont move, but this could be because they had started to get lazy and cool weather has stiffened the grease in the motors.

I want to verify if pin 27 on the ECU connector should have 12V switched live if another member could check or verify for this me. To test I used a voltage probe with the ecu connector disconnected from the ECU on pin 27 and switched the ignition on with immob disabled. When I tested It is showing as no connection when I expected to get the switched 12V+ as shown in the wiring diagram above to the ECU (J220) on pn 27.

If it is the case that I should be getting +12v on pin 27 with the ECU harness off where does the black/grey wire connect to? I used UrS4boy's thread on the AAN pinout here: as a reference too AAN T55 - ECU Connector Pin-out

This shows S64/115 thermofuse not sure if it is present on the S2 though? It shows connection to ECU and ignition coils and Shoto said. I think I will check if the POS is being powered if it is meant to be from the same. In the ABY current flow diagram schematics this is referenced as D9 on page No.73/5 and shows connection to 15 and 108.

Thanks all

[newsh]

Sorry Greg I forget, do you have a Toad alarm or other similar aftermarket alarm immob?

[Error404]

Careful with the AAN schematics as they are not 100% the same.
Pin 27 is the switched live for the ECU & coilpacks so should be +12v with ignition on. It would be a logical place to immobilise the car from, so sounds like an immob fault to me.
Trace the ECU harness back and look for a pair of wires leading to it which will be the immob loop. The ECU harness connector B on the underside of the fuse board is the black one in the row of the larger 8 pin connectors

[Greg_S]

Thanks Alex, very useful diagram. I thought as much with the 12v supply. I have had the immob out and apart to circuits and connections and have traced through to verify it is operating and supplying voltage on both of the circuits it breaks. I will double check as it is the most likely cause. I'll get back under the dash and check that connector out. I'm still a bit perplexed that the cable on my Ecu on pin 27 is black/grey rather than black as wiring diagrams suggest

[Greg_S]

Sorry Greg I forget, do you have a Toad alarm or other similar aftermarket alarm immob?

Yeah it's a toad aftermarket one. Planning to getting it changed at some point as its one that you have to touch a transponder on the dash to start which is quite annoying

[newsh]

I stripped mine out completely, no more tears

Quite often the circuits in the alarms are not up to the task of passing the amount of current needed, when the multipin connectors and or relays start to fail you can measure volts but no current flow..