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AndyGS300

Can Anyone Help Me With Alternator Problem?

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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

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

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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

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

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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.

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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.

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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

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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.

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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

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well im going to dig this thread up , as this is now the same problems im having now

it started a few days ago

the same warning lights come on the instrument panel, and the Battery slowly discharges, right to the point where the car eventually stops, luckily i was parked out side my house at this point, thinking it was the Battery which is 2 years old i took the car to lexus, after i charged the Battery up for a few hours, technician said the Battery was ok, but a little discharged and suggested a bench charge for a few days to get i up to 100%

on driving home i get the nearly dead lexus (typed above) charge it up again and everything will run till the Battery disharges,

any way, while the car was running i stuck a V meter across the Battery and i got a whopping 11.8v across the terminals when the engine running m so obviously the alternator isnt working , i had a look for the 100 amp fuse and if its the one in the engine bay, even tho i couldnt remove it to test properly it visually looks ok.

*update today*

i went out today after reading this post to see what i can see, fusae looks ok, wiring looks ok, everything looks ok, belt ok. i have notised that there is a fair bit of oil and crap on the alternator, which apparantly they dont like,

plus i went out and started the car, it started after 8 hours so its not a slow short as Battery still had enough life in to fire up it up, listening to the revs there seemed to be a noticable difference in rev speed, once speed gave me no volt increase on Battery , other speed gave me 14.1 volts, when it settled down , i got 11.5 volts across terminals,

car is a 1996 with 133k miles on, alternator is origional , im thinking its just given the ghost up , what you think

, oh a new alternator is 150 to 250 £

Steve

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Start the engine and put your voltmeter across the Battery terminals.

Should show approx 12 volts.

Get someone to press the accelerator up to about 1400 revs...you should then see 13.8 to 14.2 volts

approx., certainly more than 12volts.

Get your helper to switch on the headlights and the heated rear screen, it should still show about 13 volts plus showing that the alternator is charging under load.

It may not charge at tickover speed.

If not as above alternator fault or bad connections......

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well i got another one , mine was a broken alternator , that was easily fixed, however

my bezzie m8 has a simular problem, her lexus threw exactly the same probs as reported above, i said alternator, so she got a new alternator, highest it read from the alternator was 13 volts, that then fizzled away to nothing, ive swapped alternators with mine as i know mines OK still nothing, ive checked the fuses for the charging circuit, there ok, all cables look ok, im getting tone from all the earths, nothing looks off, but theres NO charge going to the Battery

it even ran no problem at all with a reading of 10v volts, then a few mins later it died :)

any ideas, as this ones doing my head in

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Sounds like a break in a wire to me....?

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well she has had anauto electrician out to it and he recons is a crankshaft bearing , pully thing thats collapst and its causing the belt to slip

im not 100% sure ,could be tho, seems plausable?

i didnt think there was any bearings down there, only the actual front crank bearings,

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Well, well.

This thread keeps going. I have a 97 MK1 GS300 Sport.

Engine died on me a few weeks ago - lights dimmed, warning lights came on, steering heavy etc. RAC man came out and in mucho hurry told me alternator shot.

Towed to my local helpful mechanic with instruction to take time to check, but he immediately changed alternator. Showed him this and other threads.

Still no joy, so changed 100A fuse and alternator again. By this time warning lights came up when turning steering full lock, so topped up fluid and did bleeding and problem sort of went away.

However the first time I drove it at night e.g lights, blower, rear window heater on, thing died again as originally.

Much head scratching and last night got a text to say that crankshaft harmonic pulley had separated and needs to be replaced.

EEEK am now getting fed up and very broke!

Does anyone who has gone through this rigmarole have a brief synopsis of the solution with part numbers, reasonably-priced supplier etc. ?

(Cam belt replaced @ 70K when still serviced by Lexus)

Sorry to bring this up again but getting desperate and not wishing to send the old bus to the breakers as it only has 85K miles on it

Have loved the thing from new after moving from expensive mercs (and their associated problems) with the view to it lasting me many 100's miles.

I remembered bleating to Lexus when I had to have the front suspension arms replaced at about 45K miles - gave the example of my wife's v old Astra not having to have it's suspension replaced.

Please help one very sad/depressed/desperate old fella rambling on a Sunday afternoon!

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Well, well.

This thread keeps going. I have a 97 MK1 GS300 Sport.

Engine died on me a few weeks ago - lights dimmed, warning lights came on, steering heavy etc. RAC man came out and in mucho hurry told me alternator shot.

Towed to my local helpful mechanic with instruction to take time to check, but he immediately changed alternator. Showed him this and other threads.

Still no joy, so changed 100A fuse and alternator again. By this time warning lights came up when turning steering full lock, so topped up fluid and did bleeding and problem sort of went away.

However the first time I drove it at night e.g lights, blower, rear window heater on, thing died again as originally.

Much head scratching and last night got a text to say that crankshaft harmonic pulley had separated and needs to be replaced.

EEEK am now getting fed up and very broke!

Does anyone who has gone through this rigmarole have a brief synopsis of the solution with part numbers, reasonably-priced supplier etc. ?

(Cam belt replaced @ 70K when still serviced by Lexus)

Sorry to bring this up again but getting desperate and not wishing to send the old bus to the breakers as it only has 85K miles on it

Have loved the thing from new after moving from expensive mercs (and their associated problems) with the view to it lasting me many 100's miles.

I remembered bleating to Lexus when I had to have the front suspension arms replaced at about 45K miles - gave the example of my wife's v old Astra not having to have it's suspension replaced.

Please help one very sad/depressed/desperate old fella rambling on a Sunday afternoon!

The pulley is used on other models..IS--SC--SUPRA....try a breaker?

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The pulley is used on other models..IS--SC--SUPRA....try a breaker?

Yes am aware that they are the same - hence trying to track supra item.

As per the other posts, would be loath to try a used item, considering the effort to change and consequences of it failing. After all if mine is dead after 85K, where will I find a lower mileage one.

Many thanks.

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I think they still exist so why not take the suspect alternator to a specialist rebuilder who will have the necessary jigs to actually run it on load as it would when in the car just to confirm all is OK.

I would think if a crank bearing or pulley had failed you would notice more than an alternator not charging!

Engine earth points are of paramount importance in modern cars and although they may feel tight and look OK it takes little time to remove them,clean the connector and body contact points with some emery or wire wool and then reassemble,even a slight high resistance connection can have dramatic effects.

Is the drive belt in good order and the tensioner working correctly?

Also if accessible check the voltage output from the alternator directly as well as at the +ve Battery terminal,any difference indicates a high resistance either in the connectors or the cable itself between the two.

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I think they still exist so why not take the suspect alternator to a specialist rebuilder who will have the necessary jigs to actually run it on load as it would when in the car just to confirm all is OK.

I would think if a crank bearing or pulley had failed you would notice more than an alternator not charging!

Engine earth points are of paramount importance in modern cars and although they may feel tight and look OK it takes little time to remove them,clean the connector and body contact points with some emery or wire wool and then reassemble,even a slight high resistance connection can have dramatic effects.

Is the drive belt in good order and the tensioner working correctly?

Also if accessible check the voltage output from the alternator directly as well as at the +ve battery terminal,any difference indicates a high resistance either in the connectors or the cable itself between the two.

An update and a solution???

It is the crank pulley. The rubber has gone and whilst visually belt is running, whenever major loads are put on it i.e steering at full lock the pulley slips.

Mechanic has proved this by drilling through pulley to hub and inserting screw through it thus holding the 2 together!! Hey presto alternator now charging up to 14V with all accessories on, steering held at full lock etc

Very obviously this bodging is not a solution and pulley need replacing.

Lexus part number is L13407-46020 cost 332.11 (for reference to to others with same problem e.g

post

http://www.lexusownersclub.co.uk/forum/index.php?showtopic=32237

Don't know if anyone else had dealt with these guys but $175.00 seems to be worth a chance

http://www.toysauto.co.uk/product_info.php?pName=lexus-gs300-30l-24v-2jz-9105-alloy-engine-pulley-set

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