The Mitsubishi Pajero Owners Club®

[Keith-i]

I suspect I have an alternator problem of some sort on my gen3 3.5 GDI. Last year my battery was gradually failing and after a bit of investigation I deduced it was an alternator problem. I took the alternator out and my local auto-electrician diagnosed a faulty regulator. After refitting it along with a new battery I'm still not convinced it's right. My headlights and other items noticeably dim when the revs drop down below about 1,200 to 1,500. It would be helpful to know what sort of voltage your alternator puts out at idle.

[Google]

[trekker]

A vehicle alternator will charge at engine idle speed, producing around 13-14 Volt. That's one of an alternator's advantage over the old generators. Unless your engine idle speed of around 700-800 rpm is much lower, I think you still have a problem. Is your belt correctly tensioned ?

[Crp]

Keith, just checked my 2005 3.5 GDI and I have 14.2 v measured at the battery with the engine at idle (lights, heater radio etc turned off)

Hope that helps

[Keith-i]

That's really helpful Crp, thanks for going to the trouble.

[Keith-i]

[Missing Lincs]

It might be worth a quick check of the charging connections, battery terminals etc especially the chassis end of the earth straps. Rust/corrosion is a great insulator.

[Keith-i]

Does anyone know if there is an alternator relay in the engine compartment relay box. There are 5 relays in there labelled A to E but I can't find a reference anywhere to what relay does what.

[Crp]

Keith,

Not sure you have them but have a look at these:

http://jdmfsm.info/Auto/Japan/Mitsubishi/Pajero-Montero/Manuals/

The service manual you want is the 2003 Montero Service Manual (Montero another name for shogun when sold in certain countries) .... A Fountain of information

Once again many thanks to another Forum member who sent them to me

[Keith-i]

Brilliant, thanks. I'd forgotten about that link to the manuals.

[Keith-i]

The plot thickens! I've tracked down the elusive 'alternator relay' which isn't a relay at all but rather a resistor and diode in a black box that looks like a relay. According to all the online parts databases and wiring diagrams it should live in the junction block under the dashboard - only I don't have one in mine - just a gap! Could it be the UK Shogun doesn't need one or has mine been removed by a PO? I'll grap a photo later and mark the missing spot as it would be helpful to know if other Shogun's have it or not. On the fuse block under the steering column there are 4 relays on the main panel in a 2x2 grid and then 3 or 4 vertically to the left. The suspect relay is top right of the 2x2 group. It may not be the cause of the problem but it's another thing to check/resolve.

[Keith-i]

It's at position  V on this diagram Relay box

[Keith-i]

A small update. According to Mitsi, my car doesn't have one of these 'alternator relays' or at least the chassis specific parts list does not list it. Upon further research it looks like this relay thing is actually a failsafe device (resistor/diode) to ensure the alternator gets its excitation voltage at start up in the event that the dashboard light or associated wiring fails. Perhaps Mitsi think UK drivers look after their dashboard bulbs better!

Having done some very preliminary checks on my alternator it looks like it puts out a decent charging voltage of 14+ volts at idle immediately after startup but within a minute or so it drops down to around 12.5v. This will rise to 13 - 14 volts if revved over 1,500 rpm. Whether this is the alternator playing up as it warms up a little or something to do with the ECU controlling the output via the FR & G terminals is yet to be discovered.

[trekker]

I seems the built in voltage regulator is suspect.