The Mitsubishi Pajero Owners Club®

[Keith-i]

This is a bit of a follow on from my previous thread about charging voltage at idle.

When I start the car (Gen3 3.5 V6 GDI) the alternator puts out 14.3 volts or so which is great. However after a minute or so this drops to around 12.7 and only increases if I rev the engine above about 1200 rpm. I've done as much diagnosis as I can but cannot work out whether it is the alternator playing up or the ECU control circuit.

I've monitored the voltage on the FR terminal and this starts at around 9.5v but then rises to 11 or 12v as the alternator output drops. It then drops back to about 9.5v but the alternator output doesn't increase again. From what I've read on the internet, the FR voltage should be between 9 and 10v and only ever drop as consumers are turned on. I've also monitored the G terminal and this floats at around 8v then drops to 0v and quickly rises again to 1v at the time the alternator output falls.

Without having a better understanding of the ECU control circuitry it's difficult to determine what's at fault and what to do next. I have read of the FET transistor in the ECU failing but why would this happen as the engine warms up and why would it temporarily recover if the engine is revved?

I have disconnected the FR and G terminals for the time being and will let the alternator regulator do its thing without interference. In this condition it puts out a steady 14.3v.

Any thoughts would be welcome.

[Google]

[hutchy]

when your alt was repaired did the right regulator get fitted,gdi alternators have a lot higher output than a standard alt,when mine failed i fitted one from the starter alt company,which stated it was for my engine and part no,s matched but the battery light was always faintly lit up even though it was showing as charging,i was not happy so returned it and then bought a delco remy one which cost 3 times more but i have had no issues since i fitted it and that,s on my mk2 gdi

[Keith-i]

Thanks for the info hutchy. I'm pretty sure the part is correct as the part no. they quoted on the invoice matches what my internet research suggested it should be. However, it seems like there are regulators and there are regulators so I am very tempted to buy and fit one myself. Perhaps I'll look into the options and try and buy a decent one. Presumably you rate Delco.

[hutchy]

delco are good but i would not say they are the be all and end all ive had new starter motors from delco that did not even sound right when you turn the key,and in this day and age it seems everything brand name or not are made from cheap materials and components,as it,s more about maximising profit due to being a throw away society which i hate,i don,t mind paying good money if something is going to last but it,s rare these days