Golf GTI - Weird electrical issue after rain

[edge]

Hi all,

Need your help with a weird issue I have been having with my GTI recently as my online searching for the past few weeks has taken me on a wild goose chase.

Issue:

While car is driving, it suddenly loses all drive and is stuck into Neutral (still running), all warning lights come on the dash, RPM needle goes crazy (car idles fine), gear display flashes. Turning the car on/off or disconnecting the battery doesn't do anything to restore drive or clear the warning lights. Only way the car can drive again is to reset all error codes with the OBD2 app (airbag light stays on).

This issue has happened twice and seems to be only after rain within 5-10 minutes of driving the car.

Initially I thought the issue was due to a bad battery (dealer confirmed that airbag light can be caused by low voltage) and so battery was replaced but has happened again since.

I cleared all the leaves and dirt from under the windscreen plastics to ensure drainage isn't blocked near the ECU and washed the car trying to replicate the issue, error didn't come up.

Any ideas or similar experiences?

[h100vw]

Hi all,

Need your help with a weird issue I have been having with my GTI recently as my online searching for the past few weeks has taken me on a wild goose chase.

Issue:

While car is driving, it suddenly loses all drive and is stuck into Neutral (still running), all warning lights come on the dash, RPM needle goes crazy (car idles fine), gear display flashes. Turning the car on/off or disconnecting the battery doesn't do anything to restore drive or clear the warning lights. Only way the car can drive again is to reset all error codes with the OBD2 app (airbag light stays on).

This issue has happened twice and seems to be only after rain within 5-10 minutes of driving the car.

Initially I thought the issue was due to a bad battery (dealer confirmed that airbag light can be caused by low voltage) and so battery was replaced but has happened again since.

I cleared all the leaves and dirt from under the windscreen plastics to ensure drainage isn't blocked near the ECU and washed the car trying to replicate the issue, error didn't come up.

Any ideas or similar experiences?

Did you save the fault codes?

I am sure I have read of water wicking up the looms to the ECU plugs and causing lots of drama. When investigated pins broke off the ECU and it needed a new one.

I'd be unwrapping the loom under the rain tray and having a look inside.

Gavin

[edge]

Did you save the fault codes?

I am sure I have read of water wicking up the looms to the ECU plugs and causing lots of drama. When investigated pins broke off the ECU and it needed a new one.

I'd be unwrapping the loom under the rain tray and having a look inside.

Gavin

Thanks for the reply Gavin, I didn't get to save the error codes this time around but I should have and next time I will.

I tried to remove the rain tray to access the ECU and its loom but I couldnt remove it, It looks like the windscreen was replaced earlier in its life and the installer might have actually stuck the windscreen onto the rain tray. All I could do is bend it up and reach as much as I could inside to clean it. I wonder if there is anything I can spray onto the wires and loom that will act as a water repellent

[h100vw]

Thanks for the reply Gavin, I didn't get to save the error codes this time around but I should have and next time I will.

I tried to remove the rain tray to access the ECU and its loom but I couldn't remove it, It looks like the windscreen was replaced earlier in its life and the installer might have actually stuck the windscreen onto the rain tray. All I could do is bend it up and reach as much as I could inside to clean it. I wonder if there is anything I can spray onto the wires and loom that will act as a water repellent

You can see the ecu without removing the plastic.

At the ends of the plastic cover there's a 10mm nut or bolt. Undo both. Then the steel panel with the sound proofing on can be pulled up and out of the way. The ECU is on the passenger side of centre.

You can extract the ecu and mounting bracket with a bit of effort, I do lots with tuning but you'll be able to see. To get the plugs off you'll need to remove the security fasteners though. These are shear bolts. I grab them with vice grips but in extreme cases, I'll dremel a slot and use a big flat blade screwdriver.

https://www.google.com.au/webhp?sour...0ecu%20removal

Gavin