Tiers

Hi All, I am helping a friend on a S5 rebuild and we have a problem. There is no spark. Have been doing all the troubleshooting as per manual etc. and already have a great knowledge on all this but we did have one prob that confirmation on wiring that would help.

On the CAS our harness side wire's got completely broke off and I just need confirmation on which way the wires go.

O O
B W

O O
G R

is this correct looking at the plug when connected to the CAS ( B=Blue W=White G=Green R=Red harness side colors) and as well can anyone confirm that the Blue wire is the Ne signal and the White wire is the G signal ?

Is there any chance that an S5 car cas wiring is different then an S4 ? like is the white and blue wire reversed?

I actually found a diagram discrepency in the online FSM that actually shows the CAS plug (S5 manual section G-32) connector with the G and Ne wires on the connector apparently backwards.

SOOO...

The actual problem we are having is when wired the way i think it is supposed to be we get NO spark or injector clicks. We checked wiring harness back to CPU as well as all other wires etc. If we reverse the Blue and white wires we get spark but I guess because it is the wrong signal that it is not frequent enuff. When we put it the way it is supposed to go (I believe) it sparks and injectors click once the thats it...no more.

I cannot find a short or unhooked connector or anything else anywhere.

We also have 2 ecu's and both have the same result. Though, I so far have only guessed going by troubleshooting in manuals that it says replace ecu.

Totally stumped here so any help would be greatly appreciated.

I hope I have explained and asked this clearly enuff, let me know if not.

THanks

Terry

HAILERS

Green to Green

Red to Red

Blue to White with a Black stripe

White to White

Harness colors are on the left (of the callouts above) and cas harness colors on the right. Series four.

Tiers

Ya thats what my S4 is as well and I know that I need confirmation S5 is the same...I dont see why not but we are having a weird problem so need confirmation.

As well AND possibly more important is any other thoughts on why it clicks and sparks one time then shuts off spark. (we removed cas and are spinning it to test for spark etc.)

Thanks

Tiers

This is just killing me, I cannot figure what is cutting the signal/spark/ignitor from firing.

Everything looks and tests fine so what could be interupting or shorting the white wire signal. I have gone over schematics til my eyes bleed hehehe...

I need help

philiptompkins

iTrader: (4)

i know this is kinda stupid but did u check all the grounds, including the large main one?

Tiers

Yes , in fact took harness and intake off again, checked each wire to ecu, tore harness open check all wires for shorts, re-wrapped harness re-assembled etc. and still same prob. It is a weird one too cause at this point it should work according to all checks.

I suppose it could be the ecu but we have 2 ecu's and both have the same prob when you hook it up so odds are that it is not the cpu right?

THis is all that is holding up finishing this car but I am stumped and need input

HAILERS

Looking at the plug on the Harness side and looking from the wire side of the connector:

Top left RED

Top right Green

Bottom left White

Bottom right Blue

Download the series five wiring diagrams. Ohm from the ECU thru the cas. See page B-2a of the series five wiring diagrams. See a post this day below yours that mentions the series five wiring diagrams.

I have no series five.

The wiring is a touch different in the emissions harness on a S5 vs S4.

Try disconnectong the afm plug and spin the cas and see if the spark is more consistant.

Tiers

In this pic from manual what is the GY (EM) referring to? (I know that it is some wire in the emissions harness but GY? ) and it shows semi connecting? to the B(EM) wire which I assume is the black wire ground from emissions harness. but I dont understand how it relates to the GY(EM) I mentioned. As well the way that it shows connected to all 4 CAS wires with the dotted line( ------- )...and I thought I was good at reading schematics...

I am sure it is a wire problem somewhere and maybe getting close if only I could understand this part.

HAILERS

GY is the ground wire for the shield around the four wires in the cas harness. In my opinion the car should start without the shield being grounded. Not desireable, but I don't see it not being grounded causing a no start problem.

Frankly I don't know just where that GY wire is grounded because.......I've a series four.

A o2 wire has a shield but I can guarantee you the 02 will work without that shield being grounded. Personal experience.

But, hell, go ahead and get a wire and put a alligator clip on one end and the other end to a known ground. Attach the alligator clip to the cas shield. Car still won't start most likely.

P.S. Make sure the shielded wire has NO strands touching ANY of the other four wires. That would keep the car from starting.

Tiers

Ya if its a shield then it aint the prob...(In fact this so called shield is not even in the 4 wires to cas)

dam...frustrating this is am at a loss to what to check

Tiers

Well, I am going to need some expert input here casue I am plain out of ideas. Just spent another 2 hours checking all wires connections and read voltages off egi ecu. (well all the ones you can get without a rinning car)

I suppose that it could be the ecu but had previously ruled it out as had an extra one that when hooled up has the same failure-no spark-

No one has 100% confirmed the wiring at the CAS for an S5 though but cant see why it would be different then an S4.

Sooo...can anyone offer up some expert advice etc. please

Terry

Tiers

no one has any help?

HAILERS

Yeah. Go to the pressure sensor and pull the plug off. See what the voltage is on the brown/white wire. If I remember right it should be approx 4-5vddc. If not and its only say 2vdc, then try removing the plug from the afm etc and see if the voltage rises up where it should be.

The only reason I mention that, is that it is a KNOWN that if the REF voltage of the ECU is corrupt, then you don't get spark. I doubt you have two bad ECU.

It would help if someone with a S5 would look at his cas and see how the wires match b/t the cas and engine harness.

Tiers

thanks Hailers will check that...and yes I really would like confirmation on the cas wiring on an S5 cause it seems it could be a prob as all four wires were out of the cas plug.

I cant see why thye would be different on an S4 but without confirmation ...well you know it is only a guess...

This afternoon I am back at it again as we are completely out of time in finishing this rebuild.

I forgot to mention (though shouldnt be any different) that this is an Automatic as well.

I spec'd all voltages at ecu last night and found NO probs as well as checked cas wire continuity through harness etc.

I just can't put a finger on what this could be as the system is not that complicated. I have missed something somewhere or something is shorted but dam...