Can anyone please give me some assistance.

I have a 1994 GS 300 (UK) and have been getting all the warning lights flashing on the dash for a number of weeks (Battery, Brakes, Washer Fluid, Lights etc.)

The other day they came on and have stayed on since. Shortly after the radio went off and the clock went dim. Then the engine started reving on its own between 1000 & 1500rpm. When I turned the ignition off and tried to start it again it had diffuculty starting.

On returning home I checked the battery voltage and it was about 11V so charged the battery and went to the local garage. They put the tester on the battery and told me it was the alternator that was faulty.

I have been checking the battery voltage and it is slowy reducing after a run or being left standing (with alarm on) so I presume the battery is not getting any charge from the alternator. I have checked the output from the alternator to ground and it is reading between 17 & 18V.

I am wondering if the alternator is therefore OK and if there is a problem somewhere between the alternator and the battery.

Can anyone help me and give me some idea what I can check???


Cheers

Andy

What is the voltage on the battery when the engine is running? Sounds like you have a bad earth.

Colin

I have charged the battery to about 12.8V. After staring it drops to about 12.4V and slowly reduces when left on tick over.

I have checked the continuity between the alternator housing and the chassis/battery -ve and I get a good tone on my multimeter.


Regards

Andy

if its reading 17 to 18 volts then the alternator is faulty. it should read no more then about 14volts.

I have just measured the battery voltage at 12.7V and fitted a link directly between the alternator terminal and the battery +ve.

When I started the car all the warning lights on the dash went out and the voltage across the battery was 14.3V.

After leaving it running for a few minutes and then switching off the engine the voltage across the battery is now 12.8V.

Are there any control units between the alternator and the battery or does it just go through the main fuse box.

I'm begining to suspect a broken cable under the engine somewhere, any clues where to start looking!!!!



Cheers

Andy

P.S. The 100A Alternator fuse is OK.

I would disconnect your -ve battery terminal and remove, clean and put back the leads on the alternator and also check the +ve terminal on the battery is tight before looking at the wiring. Double check the 100A fuse, it could have a hairline crack in it which will cause problems.

I've removed and cleaned the connection on the alternator and checked the connections on the battery. Still no different!!!

The connection on the alternator was black and pitted as if it had been arking. Could this have cause any other problems besides a bad connection on the alternator?



Cheers

Andy

It depends if the terminal that was arcing is crimped or soldered. I've had a soldered one come unsoldered due to being loose and arcing. You should examine the terminal closely then follow the wire back to the battery to see if any more bad connections exist. You really need someone with a good ohmeter to check the cables through.

Just to let everyone know that I've found the problem!!!

On further inspection of the connection to the alternator I noticed that the end of the cable in the lug was a bit black. As I disconnected it again to have a closer look the lug snapped off the cable.

The first 2 inches of the cable were black and burnt (presumabley caused by the arcing).

I did a botch job with another piece of cable and a couple of crocidle clips and everything seems to be OK. I am getting a new lug and crimping tool tomorrow and hope that the cable will now reach, otherwise I will have to trace the cable and replace the full length (what fun that could be!!!!)

Thanks for everyones help.


Cheers

Andy