charge light on! please help

[Nisspatrol]

ok fellas,
i took my 97 coily zook for a swim on the weekend in the mud, on the way home the charge light came on, it disappeared after a while, then it came back on, then off and then on permanantly, drove 150ks home, and i was having problems with keeping it running all the way home, it would all of a sudden conk out, id play with the coil and leads, get back in and it would run fine for about 15-20 mins and then did it again, anyway, it conked out just up the road and the batt was dead, had to push it home, washed all the mud out of the engine bay, gave the alternator a good clean, light still on, check the batt voltage not running 11.5v, voltage running 11.5v, checked voltage with the negative probe on the batt negative and the positive probe on the thick wire coming off the alternator 11.5v, removed the thick wire and checked the alt running with the red on the bolt and the black on the case of the alternator, 13.5v looks good to me?,
i think theres something wrong along the line but im buggared if i know!
can anyone point out were ive gone wrong, or a possible answer to my problem, it would be much apprieciated.
cheers heaps
warren

[familybus]

i had that exact prob on my couriour to a T and when i took it to auto elec he replaced my alternator and problem fixed! what you can try is take your battery leads off the battery while motor is runnin and see if it stalls, if your alternator is ok it should keep runnin!

[Nisspatrol]

but the alternator is generating power, 13.5v at 2500rpm?? what tha???
thanks for the reply, anyone got any ideas
cheers
warren

[bazooked]

should be the 14 volt mark under load, eg, with ur lights on at 2000 rpm.

[-Scott-]

but the alternator is generating power, 13.5v at 2500rpm?? what tha???
thanks for the reply, anyone got any ideas
cheers
warren

Check earth continuity between alternator case and battery negative terminal. It probably relies on motor-chassis earth, which may be dodgy. Also confirm continuity between alternator output and the battery positive terminal.

Good luck,

Scott

[Nisspatrol]

ok, tested again
battery connected
between pos post on alt and casing of alt, no continuity
between pos batt term and pos post on alt, continuity
between neg batt tern and casing, continuity
pos and neg batt terms off
between pos post on alt and casing of alt, no continuity
between pos batt lead and pos post on alt, continuity
between neg batt lead, veh earth and casing, continuity

heres a funny one
with both leads disconnected, multimeter set to continuity, when i put red multi probe in batt earth lead and black on pos lead, it has continuity, but not vice verca, i thought continuity was just that, continuity, with all other tests it doesnt matter which way round the probes are!
crazy, any more ideas.....please

[-Scott-]

heres a funny one
with both leads disconnected, multimeter set to continuity, when i put red multi probe in batt earth lead and black on pos lead, it has continuity, but not vice verca, i thought continuity was just that, continuity, with all other tests it doesnt matter which way round the probes are!

It's called a diode - conducts current in one direction only, and there's a few of them in your alternator.

crazy, any more ideas.....please

I'm out.

Scott

[Toy80Diesel]

If it is the same problem I've had several times after mud then its the brushes in the rear of the alternator.

You most likely need to take it out, unless you can get to the rear easily enough. remove the wires/plugs, careful with the live one from the battery. remove the cover. There should be two brushes that contact the centre shaft. Even if they look like touching the shaft, believe me they wont be. mud hold them in a position just a hair away from the shaft and causes all these problems. It can be constant and can be temporamental.
unbolt the parts that hold the brushes in, make sure they spring in and out properly to put tension onto the brushes/shaft. clean if necessary. put back together and try it out. hopefully it works for you as it has for me and a friend on several occasions!

good luck.

by the way, if the brushes are nearly gone you may wanna change them at the same time.

[F'n_Rover]

but the alternator is generating power, 13.5v at 2500rpm?? what tha???
thanks for the reply, anyone got any ideas
cheers
warren

Voltage measurement without a load connected means nothing.