Hello all
I have a 1998 2.0t which has developed a crazy fault. It will run for weeks then suddenly when I go to start in the morning the battery is Completely Flat! Nothing has been left switched on, and once it is jumped by another car it runs beautifully until the next flat battery incident which can happen at any time apparently without reason.. This is a new battery and dealer says alternator is charging properly. Sounds like a stuck relay. Any ideas?
All help greatly appreciated.

You are sure it is not a loose connection??

Thanks for your reply. The car has been at the dealers twice, all connections good, nothing left switched on, so looks like I'll test the relays. What is the best way to check they are OK without having to replace them all.

I still have trouble thinking it's a relay as suggested, and to troubleshoot a relay that only 'sometimes' sticks would seem to be very difficult. If it is a relay, tapping on them (or the starter) sometimes works. Not that it would revive a dead battery.

I personally wouldn't trust that the connections are good, and it is simple enough to clean and attach them again yourself, knowing they are good. Be sure to check the negative ground cable to the frame. And maybe you did.

Let's look closer: When the battery 'goes flat' does that mean no accessories work at all or just weakly? (headlights shine at all? wipers function at all?).

With battery fully charged, disconnect the neg battery cable. Using an ohmmeter, connect a lead to the battery cable and the other to the negative battery terminal. If more than 5 or 10 milliamp draw is noted, remove one fuse at a time, rechecking the draw after each removal, to find the drain.

On some cars the auto trans will prevent the car from starting (my 850 did this once). Releasing the handbrake and moving the car slightly allowed the car to be started. If it's a manual, the clutch switch sometimes fails.

Perhaps these things won't solve the problem. I'm just brainstorming on you.
Good luck.
Don M

Thanks for your reply,
I'll check the connections again,including the negative ground at the frame.
When the battery goes flat, nothing works, I cant use my remote to open the doors, the clock has reset to 00:00 and the radio code has reset as if I had disconnected the battery.
I dont have an ohmmeter nearby, but I can get one.
I'll let you know my progress.
Many thanks,
Chris

Before you start popping relays, check the glove box light and the trunk light making sure both of them go off when closed. If your model has a light in the engine bay, turn it off.

Klaus
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98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)