Warning lights come on when driving

[Mr Green]

My son had his car laid up for a few months and has now got it back on the road. I drove it yesterday and noticed the dash warning lights came on for about 4 seconds then went off, the service warning lights also came on but stayed on for 3 seconds longer just like they do when you fire it up, the speedo and the rev counter were still working through out this.
I thought it might be the earth terminal or a weak battery so I put it on a trickle charge over night, after 16 hours it showed green on the Optimate charger, I cleaned the earth wire and terminal and thought that would be it, I spoke too soon.
Just been out again in the rain and after 5 miles it did it again, this time occassionally the speedo and rev counter return to zero then come back into play after a few seconds.

Any suggestions/ Its a 318is E36.

[john_p]

I've had "odd behaviour" from a BMW with a flat or dying battery on a number of occasions. Dashboard lights flick on and off etc - maybe try replacing the battery as a first step?

[Mr Green]

You could be right there, yesterday when I drove it it wasn't raining so I didn't have the lights on. Today when it did it it seemed a little worse and I did have the lights(and wipers) on due to the rain. Maybe having it laid up has caused the battery to fail.

[Mr Green]

Went to my usual Tyre and Battery place for them to test the battery, it's ok so they checked the Alternator and that's ok.
Specialist spark is coming round on Friday if he can't sort it nobody can. Has anyone else had a similar problem?