Help with 1998 passat ecu/cluster communication vagcom problems

[showoff]

Hi,

I have a 1998 Passat Auto V6.

When I bought it, it wasn't running, with a flat battery.

I replaced the battery and got it running, but wouldn't idle without your foot on the throttle, and sounds like its backfiring/missing when you try and load it up.

I used my Rosstech (which I have for my audi b6) and had a kline to ground fault, unplugged, and replugged in the climate control and then it worked.
and it would talk to the ecu's, but not the auto ecu, engine ecu and not the cluster.

I pulled the carpet to find the auto ecu swimming, so I found a auto ecu with the exact same part number, and while I was there they had a engine ecu with the exact same part number. (but not a matching barrel/cluster)

With the new auto ecu in, I can now communicate with the auto ecu.

Fitting the new engine ecu the imobiliser light comes on the dash obviously, but still can't communicate.

I would like to do a throttle adaptation and also diagnose the engine ecu for fault codes to see if something else is playing up.

But I have read that the engine ecu communicates through the cluster, so if the cluster is faulty it needs replacing to talk to the engine ecu.

I have pulled the cluster out, it visually looks fine. And I can't find a suitable cluster online, let alone a set of cluster/engine ecu/ matching barrel to swap them all out.

Does any one have any ideas, can I bypass the cluster some how so I can, talk to the engine ecu and adapt/diagnose it, then once sorted plug the cluster back in?

I have been reading on line for weeks, i just don't know what to do....

[h100vw]

Hi,

I have a 1998 Passat Auto V6.

When I bought it, it wasn't running, with a flat battery.

I replaced the battery and got it running, but wouldn't idle without your foot on the throttle, and sounds like its backfiring/missing when you try and load it up.

I used my Rosstech (which I have for my audi b6) and had a kline to ground fault, unplugged, and replugged in the climate control and then it worked.
and it would talk to the ecu's, but not the auto ecu, engine ecu and not the cluster.

I pulled the carpet to find the auto ecu swimming, so I found a auto ecu with the exact same part number, and while I was there they had a engine ecu with the exact same part number. (but not a matching barrel/cluster)

With the new auto ecu in, I can now communicate with the auto ecu.

Fitting the new engine ecu the imobiliser light comes on the dash obviously, but still can't communicate.

I would like to do a throttle adaptation and also diagnose the engine ecu for fault codes to see if something else is playing up.

But I have read that the engine ecu communicates through the cluster, so if the cluster is faulty it needs replacing to talk to the engine ecu.

I have pulled the cluster out, it visually looks fine. And I can't find a suitable cluster online, let alone a set of cluster/engine ecu/ matching barrel to swap them all out.

Does any one have any ideas, can I bypass the cluster some how so I can, talk to the engine ecu and adapt/diagnose it, then once sorted plug the cluster back in?

I have been reading on line for weeks, i just don't know what to do....

I don't know anything about the V6, having never owned one. However, I am guessing they might be running an ME7 ECU. As the 1.8T AEB motors aren't particular about swapping ECUs around.

Does the engine run, even briefly with the replacement ECU fitted? This confirms that you only have an immobilisation problem

There's a VAG TACHO lead which can get the PIN from the cluster most likely and allow you to code the new ECU. (Maybe)

Another thing that might help you is swapping the immo chips between the original and replacement ECU. This isn't too big a job, just needs a hot air gun and some tweezers

[showoff]

Hi mate,

Thank you for replying, but its not an imobiliser problem, it only cranks with the new ecu, it doesn't fire and then stall like its meant to when its an imobiliser problem.

With the ecu that the car came with, when you crank it, you need to give it a little throttle, and it starts and will keep running, some times it goes to die after a few minutes, but if you feather the throttle it keeps running, if you try and load it up, it pops and misfires, that could be a coil issue for example, and it not idling without throttle could be coz it needs the throttle adapting, both of which i need to communicate with the engine ecu with the ross tech cable to diagnose....

[h100vw]

Hi mate,

Thank you for replying, but its not an imobiliser problem, it only cranks with the new ecu, it doesn't fire and then stall like its meant to when its an imobiliser problem.

With the ecu that the car came with, when you crank it, you need to give it a little throttle, and it starts and will keep running, some times it goes to die after a few minutes, but if you feather the throttle it keeps running, if you try and load it up, it pops and misfires, that could be a coil issue for example, and it not idling without throttle could be coz it needs the throttle adapting, both of which i need to communicate with the engine ecu with the ross tech cable to diagnose....

What's the ECU part number?

Have you tried disconnecting other boxes to see if they are preventing the connection? Pulling the dash fuse is another thing to try.

I don't think TB alignment.

If it's ME7, says so on the data sticker, I have a bench flash lead that would allow it to be interrogated out of the car. If it's ME7 then you can disconnect everything in the car until there's the ECU and OBD socket and have the same set up as me.

Gavin



Gavin

[Umai Naa!!]

Pull the carpet up on the passenger side as well, as there's one or two other modules under there, which will also probably have taken on water.

Also, clean out the sunroof drains

[showoff]

Hi gavin,

Its Bosch, 4D0 907 551 R, 0 261 204 690

Sorry mate i don't understand how pulling all the ecus would make a difference, if i still had a k-line fault then okay, but i can read other ecus, i couldn't read the auto ecu because it got wet, got a new one and can read it fine, the engine ecu communicates through the cluster so if the cluster isn't working i wouldn't be able to communicate with the engine ecu....

I also have pulled the whole interior out of the car, it was only wet on the drivers side, i have cleaned the harness with contact cleaner, dryed it all out and changed the ecu, the passenger side is dry.

[h100vw]

Hi gavin,

Its Bosch, 4D0 907 551 R, 0 261 204 690

Sorry mate i don't understand how pulling all the ecus would make a difference, if i still had a k-line fault then okay, but i can read other ecus, i couldn't read the auto ecu because it got wet, got a new one and can read it fine, the engine ecu communicates through the cluster so if the cluster isn't working i wouldn't be able to communicate with the engine ecu....

I can see your point on that. It's not ME7 so back to the drawing board...

Can you connect to the clocks with VCDS?

Have you got a wiring diagram of the ECU and clocks?

[Jmac]

You can jump the kline, cut it at the Engine just to bypass the actual drama, for quickness just jump straight to the k line at the 16 pin obd plug, you obviously have issues somewhere but if the clock works etc and all you want is to com with the engine try that, all this after you verified you have no aftermarket Radio, this can ground the kilne. If you do have one disconnect your radio fully and try it
Let us know,
Cheers
Jmac

[showoff]

Okay... slowly making progress... Thank you so far for the support.

Ran a wire to replace the K-line between the engine ecu and the diagnostic port.
Can now connect to the engine ecu.
Problems with the throttle body when ran a check, kept coming back.
So removed the throttle body from the car completely cleaned it with throttle body cleaner, replaced it, codes went away.
Have now successfully ran a throttle adaptation.

Now you start and it runs and stalls straight away.
17978 engine start blocked by immobilizer code is now coming up on the engine ecu faults

I'm not sure how this all works, I thought it may need a new battery in the key, but I don't think its central locking, its a simple key with one button which I think activates a light, I don't think it does anything else, so I haven't got a new battery for it
The light on top of the door trim next to the locking pin doesn't light up at all. ive tried locking and unlocking it with the key
And when I try and connect to the 25-immobilizer ecu with vagcom it won't connect...

[Umai Naa!!]

Re-adapt Immobiliser to Engine ECU? Should be able to do that in Engine ECU.