The Mitsubishi Pajero Owners Club®

[Rodspajero]

My 1992 Pajero LWB 2.5tdi (manual gearbox) stalled on a journey a few weeks ago. Ignition light and water in diesel came on together. I found the front battery was losing charge (the rear one was replaced a few months ago) so suspected faulty battery. Voltmeter readings on idle showed about 13.5 volts, then the battery light came on intermittently so I checked again and when the light was on it showed 12 volts, dropping steadily, so I assumed a faulty alternator. Having replaced the battery and alternator with new ones the I made the schoolboy error of reconnecting the alternator positive when the batteries were connected temporarily, causing a short across the alternator. (Not sure IF this is relevant so bear with me?!)
Upon starting, the ignition light and water/diesel light went out but new lights came on which hadn't been on for years (I've had it 15 years and plan to keep it) - namely the seatbelt warning, handbrake light and door open light. They went out when door closed etc but had not been on for ages before the alternator swap. also the headlight buzzer kept on when the lights were not on but engine running and the central locking failed to work. I have a remote alarm which operates on a fob and it pipped to indicate the central locking was not working although it did open and close the drivers door, as it did on the key. I believed as the ignition light went out it was charging, but this was not the case as the voltmeter registered 12.2 volts at idle and 11.6 volts with lights on (ie load) - not increasing over about 15 minutes idling. I thought I'd blown the alternator so put another new one on with the same result.
Any ideas as to what is the issue? It starts and runs fine, everything works except the central locking, and the headlight buzzer fails to work now with lights on or off. I'm fairly competent with electrics/mechanics (apart for this schoolboy error!) so want to diagnose myself if possible - if not any recommendations as to who can fix in the Peterborough area? I find it hard to believe 2 alternators are defective. My wife and me both love this truck so want to keep it for years to come, it is part of the family. Your ideas/recommendations are more than welcome, in fact essential! Thanks.

[Google]

[Simon_W]

Did you check that the polarity of the batteries were the same as those taken out?   Japanese batteries have the terminals transposed compared to European ones.  Some Pajeros have one Japanese and one EU style battery!  Check the markings on the batteries and make sure the red positive lead is actually going onto the battery terminals marked '+'.

I made this mistake on my Challenger that created all sorts of problems before I realised that I had created a positive earth version!  

[Rodspajero]

Thanks Simon - I've got 2 new identical Varta's, polarity is correct - I'm happy they're fitted the correct way as they've been out many times in the past 15 years! Not sure if there are any relays that I'm not aware of that may be an issue - Haynes manual is poor re wiring, anyone know where to find a Mitsubishi wiring diagram?

[dhammika]

Have checked al the related wiring diagrams and cannot find a possible reason for your lights.

Please check No 11 fuse in the junction box in the driver's footwell.

[Rodspajero]

Still having serious problems - I've checked the wiring from the alternator to the battery and back to the starter motor and there is no damage to the wiring at all, which had been suggested by an electrician I contacted. Paj off road at the moment and I want/need it back.

Question to those experts in electrics please? … I put a new 100 amp fuse in the Paj and drove it about 50 miles in the dark, lights on and no issues, fuse not burning. Then did a 10 mile run with wipers on due to rain and when I got home the blue 100 amp fuse had blown. The wire from the alternator goes direct to a yellow 60amp fuse in the relay box in the engine compartment and is then bridged to the blue 100 amp fuse. From there runs a series of wires which I haven't checked as I was advised that it must purely be an alternator wiring issue.

Question1... Is it likely that there is a wiring fault in this area, if so how can I test without having to expose the wiring to check for an obvious short?

Question2... Could it be an alternator issue? Still not convinced the replacement alternator (Chinese but labelled Bosch) isn't faulty? It kicks out 14 volts when fuse isn't blown, but nothing when fuse is blown.

Any other obvious (or not obvious?) checks I need to do?

Hoping one of you guys are able to help - if not can anyone recommend a good electrical engineer Grantham area?... Many thanks!

[assassin]

Maybe a silly question but have you checked your vehicle earths?

Often they corrode and this cannot be seen unless the earth straps are removed and you seee rust behind them and they cause these intermittent problems, clean to bare metal, assemble, and spray with Waxoyl as this is electrically inert and prevents corrosion.

Battery connectors are another problem, often they are poorly fitting or corrode inside the fitting to battery post, and often the battery post is oxidised and a combination of this drops your system voltage to below 9V when you crank the engine.

Simple test: connect both batteries correctly and clean a good earth on your engine and run a jump lead from the battery negative terminal to your cleaned section on your engine and start the engine, if it starts and runs with the temporary jump lead connected it suggests a poor earth somewhere.

[Rodspajero]

Thanks Assassin - under normal conditions the Paj charges (14.4 volts) and runs well, it's when the fuse blows that it doesn't charge, guess it breaks connection between alternator and battery. Would earth issues cause a short and the fuse to blow? The fault occurred immediately after replacing the alternator (and I did briefly short the positive on the alternator to earth which sparked - stupidly I hadn't disconnected the battery earth straps) so I've been assuming that the fault lies around that issue?

[assassin]

It would appear to be a faulty alternator then, get it tested and claim it was that way when you got it.

Sensing comes in two forms, first is the machine sensed alternator which are generally fitted to most vehicles and automotive applications, and there is the battery sensed alternator, what is the difference.

Alternators sense their output and regulate themselves and a machine sensed alternator does this internally and any bad wiring or earths does not register with the alternator and it regulates its output according to what it thinks the batteries need; battery sensed alternators need a seperate tag soldering into them and this has a wire soldered to it and this wire goes straight to the battery terminal from the alternator and measures what the battery actually needs direct from the battery and this is a more accurate way of controlling the alternator output as it accounts for bad or corroded connections as it reads from the battery itself and regulates exactly what the battery demands with corroded terminals or connections and raises the voltage and current to compensate.

[stezario]

Hi Rod, out seems I don't have enough points to send you a pm. Regarding your message or turns out I'd bought a bad batch of 100amp fuses (from eBay). All 10 were made of foil, practically! As soon as I bought a decent one from eurocarparts the issue was solved. Sadly I'd lost faith in the truck by then and sold it soon after.