Alternator Issues?

[fred130111]

Engine is a rev3 NA

From what I can tell all wires are in the correct place ( recently changed the engine ) however the alternator is not charging the battery, wondering if it is a dodgy earth.

Charged the battery and the car starts fine, looking at the built in volt meter as soon as the car starts the voltage drops.

Can anyone help with basic checks etc?

Thanks, any help is greatly appreciated.

[Peter Gidden]

Can anyone help with basic checks etc?.

Search button at the top of the page will have revealed loads of threads with the test.

With ignition on, check the voltage of the 3 pins in the plug. All should read 12V. If they do, alternator dead. If not, problem is on the circuit with the low voltage.

[fred130111]

Thanks peter!

I will investigate this later today, Also noticed the battery light stays on and I know the alternator is not seized as the pully spins freely. Wondering if I have not attached something during the engine change. Probably

[fred130111]

Ok so I tested the 3 pin connector, 11v at all three pins
Tested the big ring connector and also 11v

When the car starts the power drops slightly, Tried a different battery and the same result but at 12v and the battery light still stays on, based on all this can we confirm this is a fault with the alternator? I assume so.

So does anyone know the best / cheapest place to get alternators reconditioned as for a new one I have been getting quotes for around £200




Thanks

[Mr2Madlad]

Make sure the engine earth lead is bolted to the engine and chassis if not even with the signal present on the small 3 pin alternator plug the battery will not charge as no complete circuit due to rubber engine mount isolating engine from chassis.

Case of alternator is bolted to engine this is the 0 volts / GND output back to battery - terminal (via the engine earth lead) if missing i.e air gap no circuit and no charging of battery.

Fat stiff bolt on wire is the alternator DC output back to the battery + terminal via the large 120 amp "ALT" Fuse in the front trunk. should be 12 v all the time and spark like a mo fo if shorted to ground for a very small period of time (not recommended !)