Hello,

Had a crank no start. Bosch starter motor reconditioned fitted. Car starts each and every time for a month since fitting.

Wife noticed radio (Kenwood aftermarket) loses power on cranking and resets or stays shut down. Radio fitted 1 year ago and only shut down when battery was knackered. Turning off fan, lights had no effect. Radio loses power when starting every time, warm or cold engine.

Looks like a voltage drop. Dash lights unaffected. I already cleaned all earth points in engine bay. I checked the negative battery cable to suspension turret earth. Put extra cable on it in case breakage (jump lead). Radio still loses power momentarily forcing reset. Presets not lost.

Battery is healthy and reading over 12.6v

AI Google says to fit a capacitor plus loom behind radio to drop the voltage drop. Anything else I can do? The battery is bigger than needed. 540Cca and it got at least 100 cca so I'm thinking is there a weak ground.

Radio needs ignition on to power up - switched live. Could red and yellow wires be wrong way around, but then radio would be on all time = flat battery on constant live.

Also seen a little brown wire slightly frayed on neg battery terminal. It is used for control systems on car and provides clean voltage unlike earth points. Could that be to blame?

Any ideas appreciated.

Check the battery voltage while engine is being cranked - likely that voltage is dropping too low during engine crank.

From memory the yellow wire I think is permanent live and red is from ignition. The yellow wire is there to keep settings etc. It may be that the Kenwood is more susceptible to voltage drop. Check that the yellow wire is getting 12v with ignition off.

Alasdair