Hi there,

I have two Octavia 4x4 1.8T - both 51 plates - 1U23QX.

One of them has developed an annoying intermittent electrical fault - I first noticed it then the key was removed, the radio stayed on.

I WD40'd the ignition lock, which seemed to cure it. For a day or two.

Then one of the rear windows wouldn't go back up using either switch. And I was unable to lock the car with the remote button. But the next day it was OK again.

I disconnected and reconnected the battery (resetting the ECU?), which seemed to fix it. Then a few days later after the key was removed I tried the rear offside window, and it operated in 'steps' as if it was connected to the indicator circuit or similar- ie. whilst I was holding the button down, the window started and stopped going down in equal steps of about one second.

I swapped the 'windows/door lock control switch' unit in the drivers door from my other car, but the intermittent fault remains. So sometimes the radio stays on when the key is removed (and I'm unable to lock the car). And sometimes the windows stop working completely, or continue working when the key is removed, or the steps thing.

My next thought is to swap over the ECU's between cars, but I'm not sure if I might end up with two 'non-runners'! I've checked the log books for both cars, and all of the numbers on the grid inside the cover are exactly the same except one (8YP for one and 8YD for the other).

My eBay code reader shows 'no codes'.

Has anyone had anything similar? I've spent a few hours trawling the net, but to no avail. Any advice would be greatly appreciated.

Many thanks,

Nick.

Edited 7 January, 201214 yr by Nick F

Swapping the ECU's over isn't going to help, & will give you 2 cars that won't start.

Most likely cause of your problems is the central convenience unit or corrosion or water in the drivers door multi-connector. It sounds to me like you have moisture collected somewhere which is causing short circuits.

Edited 7 January, 201214 yr by pauldazzle

As above I would agree with the 'convenience unit' being at fault.. that would be an educated guess.. It's pretty common with these and can cause all sorts of issues with electrics from central locking - audio issues

DO NOT SWAP BOTH ECU's The immobiliser will actually poo itself and won't recognise the key/ecu combination..

Hello again,

Many thanks for the replies.

I've spent the last couple of hours dismantling the dash and drivers door in search of the central convenience unit and door multi-connector hoping for an obvious fault.

Unfortunately, all of the bits (connectors etc) look brand new - no hint of moisture anywhere. Whilst I had the tools out, I took a look at the connector for the CD multi-changer, as I read somewhere that it can also be a cause of strange electrical problems. Same story though - it all looks fine.

The intermittent fault remains - I tried the rear drivers side window (with the key out) it's pulsing the window down in one second steps. The radio also stayed on with the key out. After a short drive, both faults disappeared.

Could it be possible that the central convenience unit is faulty (I took a look inside at the PCB - no obvious problems), or the other unit in the drivers door?

I was also wondering if there are any more 'awkward to find' control units hidden somewhere causing the problems, or maybe a relay sticking or something?

Any more ideas please??

Cheers,

Nick.

Update...

I've just driven the car at night (first time for a while) -

To add to the list of previous faults, I noticed that the radio backlight comes on and off at random intervals (the main display). When I took the key out, the display went out but the backlight for the radio buttons remained on. And the courtesy light sometimes works, and sometimes doesn't.

Could this be a faulty CCU? I'm on the verge of trying a new one.

Any thoughts out there. Please....!

Cheers,

Nick.