Any experts with 90 electrics.

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
Fatboy11

Fatboy11

New Member
Posts
1,074
Location
Thatcham, Berkshire.
Really having major problems with my alternator(s) at the moment.

I have a new battery a new alternator and have cleaned all the earth connectors I can find.

I went out on Monday and the alternator was fine for most of the day (14v ish on voltmeter) then at the end if the day the voltmeter had dropped to just above 12v and the battery warning light was lit dimly. Thus is the 3rd alternator that has been put it in in a year.

Anyone offer any advice as to why the alternator stops working ?
Do I keep blowing the diodes because of some electrical fault ? Is this possible ?
Could it just be bad earthing stopping the alternator from kicking out the correct voltage ?

Thanks for any help.
Jason
 
Forgot to mention when the alternator was working the battery light would light normally when switching ignition light on although oil light was dim. But when the alternator stopped working both the battery and oil lights are lit dimly.
 
Are these new or recon alternators, after many bad experiences I've given up with reconditioned anything, if there's no obvious reason I'd try a new one if you're using recons
 
my battery light was glowing dimly a few weeks back and 30 seconds later my dash went up in flames followed by the cigarette lighter and stereo wiring. as i stripped it back one wire at a time i found that a number of wires under the dash liner tray had worn thru where they bend and drop thru the dash into the fuse box causing a short which fired most of the wiring and melted the insulation, might be worth a look under the tray if you cant find an obvious bad earth.
 
i had this on me 90 a while back went thru 3 alternators in about 3 months all new ones

1st one was replaced straight away
2nd one they wanted it back to test under warranty
3rd one was a fight i had to purchase another new one while the investigated my old 3rd one

turned out they had a whole batch of faulty ones all the 100 amp model

so before u go beating yourself up over whats wrong with your 90 get the alternator looked at/replaced under warranty
 
Either another faulty alternator or the wiring between the battery and alternator is damaged.

When you checked the charge, was it at the battery end? Put your metre on the alternator.

Just a thought: check the connections on the ignition - they may have worn or be damaged.

Good luck.
 
Just a couple of things to add.

I think I would check the engine has a good earth rather than just a clean up of the terminals. Just because sometimes the cable assembly will corrode over time (and possibly vibration and temperature) and build up resistance, especially if there are any wire braid type earth straps.

The other thing that springs to mind it to ask whether your fan belt(s) are tight? If it is slipping, it might not be turning your alternator properly.

And, when you say at the end of the day the voltage was about 12 volt, you do still mean while the engine is running don't you?
 
wiltshire landyman said:
i had this on me 90 a while back went thru 3 alternators in about 3 months all new ones

1st one was replaced straight away
2nd one they wanted it back to test under warranty
3rd one was a fight i had to purchase another new one while the investigated my old 3rd one

turned out they had a whole batch of faulty ones all the 100 amp model

so before u go beating yourself up over whats wrong with your 90 get the alternator looked at/replaced under warranty
Click to expand...

Can you get 100 amp alternators for a 1991 110?
 
Thanks for all the advice

mundungus said:
And, when you say at the end of the day the voltage was about 12 volt, you do still mean while the engine is running don't you?
Click to expand...

Yes the engine was running when the voltage dropped to just above 12v.

It may be that it's a cheap alternator I have been using and it's not up to the job, but I don't want to buy an OEM one if there is a problem and I'm just going to break that one too.

Can I replicate earth cables with jump leads between battery/ chassis/ gearbox/ engine to see if that helps ?
 
Fatboy11 said:
Forgot to mention when the alternator was working the battery light would light normally when switching ignition light on although oil light was dim. But when the alternator stopped working both the battery and oil lights are lit dimly.
Click to expand...


From this diescription I would start looking for a short circuit in the wiring behind the dash.
 
Yes you can replicate an earth strap with a jump lead from the engine to the battery.
Check for any short circuit or any nasty draws from the battery. Switch of the interior light, Remove earth connection at the battery and use your multimeter on the amp DC setting put one lead on the battery and put the other ont the eartgh clamp and see what your reading it should be less than 0.5 amp. if it is higher start pulling out fuses to see if it drops. if all of the fuses are out and it still has a high drain then i would disconnect the alternator. if that doesnt cure it check the wiring between the alternator and starter. If that still doesnt sort it you will have to start taking things to bits to check for damaged wiring.

If you susspect an earthing fault you connect a jump lead from the engine to the battery clamp.
 
That's nearly an amp. That's quite a significant current drop if the ignition is off.

Time to start pulling each fuse one by one to see which ones make that figure drop significantly.
 
The fuse is the cigarette lighter one.

So I guess the question is, would this be causing the alternator to blow/ stop working ?

Also does this 0.9a reading mean that there is a short somewhere on the lighter circuit ?

Cheers
 
So what does the current draw go down to when that fuse is removed?

I can't imagine a short on that circuit will impede the alternator operation in any way, but it would explain if your battery is going flat. Also, if the short is intermittently changing from better to worse (e.g like a frayed wire rubbing on the body work) it could explain your low reading of 12v whilst running.
 
Actually just to clarify that, i guess buy continuously shorting out the alternator whilst it's running could damage the internals over time. It depends on the regulator circuit inside the thing.
 
The current flow dropped to 0 with the fuse removed.

The alternator only lasted 1 day from new so it must have got damaged quite quickly.

I'll think I'll have to check all the wiring behind dashboard to see what state it's in.

Cheers
 
You must log in or register to reply here.

Similar threads

J
Help please! Electrical issue with 1995 Defender 110 County, 300 tdi
2
Replies
36
Views
3K
KISSMYAURA
KISSMYAURA
F
TD5 Fuel pump mystery
Replies
3
Views
488
Brown
Brown
DefendingLancashire
Advice on decent flasher relay replacements? (1996 Defender 90)
Replies
0
Views
328
DefendingLancashire
DefendingLancashire
S
1988 90 replacing lights with LEDs and have lots of questions
Replies
5
Views
1K
sleepybear
S
8
2008 Range Rover sport L320 crank no fuel no start . 2.7tdv6
Replies
1
Views
942
psychmarz
P
Back
Top