Powerlite starter diode

ratwing · Post by **ratwing** » Thu Mar 13, 2014 4:11 pm

I've bought one (RAC318) for my Rover p6 V8 but although it turns over ok it won't start, it always started easily before when the old starter was working.
There isn't a terminal for the cold start lead and the little leaflet that came with it says if it won't start then connect it using "a large diode".
Has anyone else had this problem and if so what sort of diode did you use?

ChrisJC · Post by **ChrisJC** » Thu Mar 13, 2014 6:11 pm

Eh?, the only reference I can find for a starter diode would be if you were controlling the starter with some sensitive electronics. If the engine is cranking, the diode is a red herring.

Chris.,

ChrisJC · Post by **ChrisJC** » Thu Mar 13, 2014 6:12 pm

It's more likely that there is a problem with the wiring to the ballast resistor, or rather, the bypass of the ballast resistor whilst cranking.

You could temporarily short the ballast resistor out and see if she fires up.

Chris.

ratwing · Post by **ratwing** » Thu Mar 13, 2014 9:55 pm

ChrisJC wrote:It's more likely that there is a problem with the wiring to the ballast resistor, or rather, the bypass of the ballast resistor whilst cranking.

You could temporarily short the ballast resistor out and see if she fires up.

Chris.

So you mean connect the spare wire (that used to go to the second terminal on the solenoid) to earth or to live?
It just seems odd that it always fired up no problem but now the new starter is on and theres a spare wire no longer connected to anything, it won't start. (presumably thats why they say fit a diode on that wire so it can be reconnected somewhere?)

SimpleSimon · Post by **SimpleSimon** » Thu Mar 13, 2014 10:53 pm

The reason you need the diode is if you connect the ballast/cold start wire to the solenoid trigger terminal then when you start the engine there is a chance the starter will stay engaged due to the starter solenoid staying energized

if you fit a diode you stop voltage fly-back to the trigger terminal only allowing voltage to the cold start wire from trigger wire while cranking

ratwing · Post by **ratwing** » Fri Mar 14, 2014 5:48 pm

Cheers, I see what you mean - that makes sense, just got to search and see what diode to use now.

DaveEFI · Post by **DaveEFI** » Fri Mar 14, 2014 11:40 pm

Assuming it's going into a relay coil circuit, a 1N4001 will be fine.

ratwing · Post by **ratwing** » Sat Mar 15, 2014 4:23 pm

Thanks for the info, 99p for 10 on fleabay so cheap too

ratwing · Post by **ratwing** » Wed Mar 26, 2014 4:18 pm

I soldered one to a ring terminal and male spade, installed it and we're back to first time starting again

. Thanks for the help guys.
ps I got a reply from Powerlite, they do a diode for £9.60 +p&p