Our lovely LET into a Mk3 Astra Cabriolet project has developed a strange fault. What happens is when switching the ignition on the injection fault light doesn't come on, which literally means the ECU hasn't booted up. It doesn't loose it's memory as it nearly always had the first gear fault code stored till recently (sorted now, speedo sender removed).
So obviously the engine will turn over fine but not start.
Thing is, if you raise the battery voltage just a tiny bit, by connecting a charger, another running car or even just another battery it will come back on and the car will start, even if you just connect a trickle charger for a few seconds.
The battery has been changed a few times for brand new ones, the alternator has been rebuilt, and the engine turns over ok. In short, the battery is not flat at all.
I'm worried the ECU is on it's way out, any other opinions? Maybe a dry joint ojn the board?