The battery light comes on OK with the turn of the ignition switch and goes off when the engine starts but he battery voltage stays at about 12.5V. Is there a fuse in the alternator feed and where is it located? Thanks
franc123,
Apr 26, 6:03pm
What is the voltage doing when its revved a bit, or if the headlights are turned on?
bigfatmat1,
Apr 26, 11:18pm
yes fuse at the battery bunch of them on positive terminal often corroded up. easiest way is to check with a multimeter voltage at the alt B+ then again at battery should be no more than 1v vd. A failed diode could also drop the output of the alternator with out bringing warning light on. Same as a loose belt or stuffed harmonic balancer.
intrade,
Apr 26, 11:55pm
how old is this vehicle would be my first question. ? if its new and it has a smart charger then it wont charge the battery to save fuel and thus better emissions. unless it has to charge!. Smart charger charge on downhills when the vehilce goes in to overrun to save fuel and meed tuff emission standards. Its all about emissions number 1 then fuel saving bmw ford use these smart chargers amoung 100s other stuff like paper thin wires toyota use to save a few grams on the total kg of a cars waight , loads of fun with ultra thin wires that snap and corode with a breeze of sea wind.
rctr,
Apr 27, 12:09am
Come on intrade it's an l300 even in brand new ones the most modern tech in them is the cd player from 2005
The fuse will be bolted in. remove cover in bolt. Have you checked it first no point pulling it apart if it's ok
p.monro,
Apr 27, 6:04pm
It is awkward to check because of its location and I have not found how to remove the cover. I can see the bolts ok. At present I am working between the showers but I just checked continuity between the battery terminal and the wire connection at the rear and it seems to be open. I can not absolutely confirm this because it is physically awkward to be sure of the meter contact. The rear connection has two white wires, red stripe in the same lug. The alternator has the same colour wire When the rain clears I will check voltage at this wire with the motor running. I hope it is 14V approx. Thanks for your interest
p.monro,
Apr 27, 7:37pm
I checked the voltage at the voltage at the WR wire at the rear of the box. It was zero. It should have been 12.5V. With the motor running it was 30V+. It appears to me that the fuse link is open and that the Alternator is OK. I guess it will go to the Auto electrician tomorrow. I do not have a fuse link in my spares
bigfatmat1,
Apr 27, 7:43pm
Better hope that running it open circuit ddid not do any damage as well repco supersheep sell the fuses
p.monro,
Apr 28, 2:19pm
The 30+V looks a bit high but I guess it is OK. I am not worried about that. I finally got the cover off and removed the fuse. It is open. I looked on trademe for the fuse but it is not offered. Thanks for your comment about repco Supercheap . I will go there this morning. Thanks for your interest. It was very helpul
aredwood,
Apr 29, 12:20am
Now you need to figure out why it blew in the first place. My pick is voltage reg running open loop. (alternator outputs as much voltage as possible). You soon find out what is the weakest link out of: alternator, alt fuse, battery, alternator to battery wiring, various electronic devices that don't like overvoltage. You haven't had alot of lightbulbs fail recently by any chance?
Or you have a loud sound system or grunty inverter.
bigfatmat1,
Apr 29, 2:00am
? The voltage was high because fuse was blown! open circuit voltage from alternator. No where to go it wont damage any componants because its open circuit!The most likely cause of that particular fuse blowing is reverse polarity jump start or batt installation and terminals connected backwards. the only other way the fuse will blow is a short in the B+ supply to alternator!
bigfatmat1,
Apr 29, 2:02am
by damage I meant to the alternator only! they do not like being run opencircuit to long
p.monro,
Apr 29, 2:50pm
I put the new fuse in but I was a bit lucky. Because of the weather I was working in a shed which does not have lighting . I was using a torch so it was pretty dark. After I assembled the fuse I touched it on the battery terminal to see if it was drawing current and saw an arc where the battery compartment where the cable loom passes through to the engine compartment. On inspection I noticed that the loom wrapping and wire insulation. were completely worn through. If the lighting had been good I would not have seen it. Thus the explanation for the blown fuse. I took 50mm of plastic hose ,slit it lengthwise and put it over the cable. It was too awkward to get in there to tape up the damaged wire still in the loom. The alternator is OK. It shows a rise in battery voltage to about 14V when the engine starts and a drop in voltage when the engine stops. I suggest that if you own an l300 you check the cable loom where it passes out of the battery compartment.
bigfatmat1,
Apr 29, 7:10pm
Good result. Glad you found the cause.
intrade,
Feb 19, 11:19am
yes and you now kow you dont just swap a fuse because its blowen like a swaptron moron, because you know now the fuse has blowen for a reason and is only a symptom to a other problem.
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