no power getting to my 9a ISV

[ollster 0]

can someone explain how the ISV system works on a 2l 16v 9a engine. Basically i am getting no power to mine and although the car still runs withgout stalling im 100% sure it would run a hell of a lot bettter from cold with a working ISV. Is it possible that the ECU output for it is fried or is it more lightly to be wiring.

 

I get no buzzing noise from it at all and it throws up a perminant error on vag com:

 

04E9 :Idle actuator Op.circ/Ground short

[Supercharged 2]

Have you taken the plug off and checked for power?

[ollster 0]

yes, it was checked at a bosch dealer and no power at the plug with the ignition on. It should be battery voltage shouldnt it? I take it the 9a's dont have a control box like the kr's?

[bcstudent 0]

This is another piece of the 9A puzzle I'd love to understand too!

[RW1 0]

I take it the 9a's dont have a control box like the kr's?

 

Yep, the KE Motronic ECU controls the ISV directly like the VR6 ECU.

 

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First of all, is fuse 15 (10 amps) OK? This is the source supply to the ISV, 12 volts ignition.

 

The ISV has the ignition 12 volts on the black with white stripe wire. The black wire goes to the ECU plug on pin 17 and is the on/off signal demand and is effectively the electronic "grounding" wire to the circuit to actuate the ISV.

 

If no ignition volts on the black with white stripe wire, also check the cold start valve’s ignition 12 volts supply on it’s black with white stripe. This uses the same 12 volt source and the wires are spliced in the ECU loom.

 

 

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[ollster 0]

ok so what other factors could be stopping it from getting power for example if the idle switch wasnt making a circuit would that cause no power or buzzing of the isv with the ignition on. has anybody got wiring diagrams for the 9a ISV system?

[RW1 0]

“POWER”

- Ignition ON 12 volts via Fuse 15.

- Through plug position G2, pin 4 on the back of the fuse/relay panel.

- Plug G2 is 9th plug (White) on the top row from the end that starts immediately with a multi pin 8 way yellow plug, not the end from the 3 single connectors.

- Pin 4 of G2 has a black wire with white stripe, which splices in the ECU loom several ways**.

- Black wire with white strip comes out at the ISV plug.

 

Nowt else is involved, no idle switches. The idle switch is down stream on the far side of the ECU electronics signalling the ECU, not the ISV.

 

** cold start valve black wire with white strip should have ignition 12 volts as this is off the same splice in the ECU loom.

[ollster 0]

Sorry mate i didnt read your fist post correctly, i mentally discounted everthing below the line in your first post as a sig lol

 

right fuse 15 checks out is it worth switching the ignition on and putting a multimeter accross fuse 15 slot to make sure there is power there?

 

So it is doubtfull that it would be a faulty ecu as the isv should get power through the black wire with a white stripe with the ignition on anyway which it is not. I take it the next logical step would be to see if the cold start valve is getting power with the ignition on?

 

Thanks for this i have something to go on now :)

[ollster 0]

ok so just checked with the ignition on i get power to the CSV via the black and white wire but nothing from the black and white wire which go to the ISV. The other wire to the ISV has a very small voltage with the ignition on so i am guessing this is a the ecu switching it on but without 12v the isv will not buzz?

 

So next where is the black and white wire spliced to both the CSV and ISV and where is the ISV earthed as one of these this must be the cause. I also tried testing the black and white wire to the ISV before the connector and there was still nothing with the ignition on... the saga contrinues but i think im getting closer lol

[-Neil- 0]

olly when your start it up does it take a good few seconds of the starter to get it up and running?

[RW1 0]

CSV via the black and white wire but nothing from the black and white wire which go to the ISV.

Check the wire as far back as you can go in the loom with a pin and see if you can get 12 volts with igniton on. If OK, either a broken wire between the connector and where you've peirced it. If not, then your into opening up the loom. To determine that, you need to look where all the black/white stripe wires enter the loom as it feeds across the car. Things on the "branched" black /white stripe wire are: Carbon canister solenoid valve (2 wires the same), cold start valve, ISV & gearbox speed sender.

 

My guess is that the wire may be broken inside the insulation sleeve just as it leaves the ISV plug. But If I understand you right, "black and white wire to the ISV before the connector" so that is kyewashed. Does the wire twist/bend anywhere further back? If so, test on the fuse/relay panel side for 12 volts. Has it chaffed on something and burnt out?

 

without 12v the isv will not buzz

Oui.

 

 

where is the ISV earthed

That is the ECU's internal function. Electronically switched. The fact you have no 12 volts on the black wire/white stripe is you problem. Cannot at this stage see the relevance of chasisng the earth side. Sort the 12 volts out first onto the ISV plug via the black/white stripe wire from the fuse/relay panel.

 

 

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[ollster 0]

right a bit of progression i have managed to get the isv working by disconnecting the CSV and using the blk/wht power feed from that along with the ecu solid white wire from the existing ISV plug. I know its working as the car fires up better form cold and the revs go all over the place which i am guessing is because the isv is full of crap and hasnt run for a while.

 

I have tried to find the break in the wire to the ISV but without any joy and i cant find where they are spliced so would it be ok to take a feed off the blk/wht wire to the cold start valve and have this running both the isv and the csv i take it this is all that is dont somewhere up stream?

[RW1 0]

You may get away with cross linking the ISV's supply wire to the CSV but....

 

The wire out of the fuse/relay panel is a 1mm wire which then splits into 4 ways into 0.5mm wire. The ISV could just be overating the wires if hung on the CSV wire.

 

You don't know what the failure is and loading up another part of the loom could melf things. I would be happier to say yes if the reason for this happening had been found so I'm inclined to bypass the loom by going backto the fuse/relay panel area for your pick-up point.

 

The safe way is to run a wire off one of the ignition single point connections on the back of the fuse/relay panel to the ISV with an in line fuse or....

 

Find the 1mm black with white stripe wire on the back of the fuse/relay panel at plug position G2, pin 4. Plug G2 is 9th plug (White) on the top row from the end that starts immediately with a multi pin 8 way yellow plug. Splice your new connection for the ISV from here as it's derivingits power at this point in the same way as the original loom. Run the feed through the bulkhead into the engine bay.. etc,.

 

I'm surprised you didn't find it. Did you check out the loom ISV wire at the fuse/relay panel end before it dissappears into the loom? ie. plug G2 pin 4 and where does it go to.

 

The splice 4 ways I would expect to be before the first black with white stripe pops out of the loom assembly to one of the 4 items listed earlier on. It's curious why it has broken as where I would expect to find it, its not likely to get broken unless you did something in the engine bay recently or under the dash. Any thing come to mind?????

 

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[ollster 0]

cheers for all the help RW1 you ahve been a star, i traced the wire from the ISV as far as teh back of the gearbox before i gave up on that one. And from the fuse box end i could see the thicker gauge blk/wht wire going into g2 pin 4 but it just dissapers into a the loom, so unless someone could confirm where it is spliced i do not fancy unwrapping all of the loom!

 

For the time being i have spliced off the CSV feed and both the CSV and ISV have power and are working fine. The wire just before the join is not getting hot so i am hoping it will not cause problems, but i would still prefer to find the orignial splice and connect everything up as per factory if anyone could help me locate it

[dubweiser 0]

hi mate,contrary to popular belief(in my experience anyway),the isv doesnt "buzz"like everyone says it does,and if it doesnt it dont mean its paggered.Mine never has and i thought it was faulty but it aint.Also,i didnt realise vag com was able to diagnose such things as this for this engine,only basic stuff????