Mercedes Benz O305/7 starting issue

[BembokaO305]

Hi all, I'm trying to move an old MB305 for a friend and it refuses to turn over. We have put two good batteries in it, pushed in the key and pushed the start button. The centre relay/solenoid clicks (quite audible) but nothing else. Is there any other master kill switch that may be the problem? It was running okay about 12 months ago apparently. The park brake is engaged and gear shift is in neutral. Are there any other safety checks which might be stopping it? Thanks Paul, Bemboka NSW

[BembokaO305]

And a related question, do these buses use a positive earth electrical system? I have connected the two batteries to the bus according to the colour of the terminals .... ie red connected to positive end of battery. But this cable seems to go straight to a large solenoid and from that solenoid the other cable is attached to the chassis .... thoughts?

[boronia]

Check for a safety isolation switch on the engine hatch. Some buses won't start if this is open. or not closed properly.

[Guy_Arab]

IF YOU REQUIRE A WIRING DATA CONTACT ME I SEND IT FREE
GUY ARAB tram1one@bigpond.com

[BembokaO305]

Thanks boronia, I'll check that out. Email sent Guy, thanks.

[BembokaO305]

Anyone on here currently driving one of these around? Especially if it's not too modified... I would love to able to talk through the details with you.