charging circuit fault - Land Rover 90

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policybuddy

New Member
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Hi, I'm having an issue with my 1989 2.5td Land Rover 90..

Battery keeps draning and I've noticed the battery light doesnt come on with the key in ignition, oil does as normal. I've changed the bulb and checked that i'm getting power up to the instrument display. 12v to brown/yellow when all connected up to dash and 12v at the other end of the brown/yellow at the alternator.Both of the other cables on the alternator also getting 12v. This I assume means no break in the cable? Alternator was changed a year ago and so was the battery.

Now to confuse things this happened a few moths ago. All I did then was unravel the tape back to the bulk head, clean the connectors on the back of the instrumnet panel and remove the voltage regulator on the back of the alternator to check for lose connections. One of these seemed to work but unfortunately the same not working this time.

Any Ideas what to look at next?

Many thanks
 
Thank you, so with the key in ignition on first click and the plastic cover off the plug that goes into the back of the alternator all 3 wires have 12v but still no battery light, again the yellow brown wire from alternator to instrument bulb also getting the 12v...alternator you think? I'd also checked the solenoid wire as i'd read maybe this shares the same feed but this all looks fine

cheers
 
remove plug at alt ,two thick wires should have battery 12v thin 12v ignition live ie only live when ignitions on check if ok alt needs changing or repair
 
ok, ignition off and alt plug unplugged, get nowt from the small bulb feed but both of the thicker brown cables giving just over 12v with no key in ignition... Not sure if I need to mention that for example the radio has always worked if needed with no key in ignition. the only other thing changed recently was the ignition barrel

many thanks
 
policybuddy said:
ok, ignition off and alt plug unplugged, get nowt from the small bulb feed but both of the thicker brown cables giving just over 12v with no key in ignition... Not sure if I need to mention that for example the radio has always worked if needed with no key in ignition. the only other thing changed recently was the ignition barrel

many thanks
Click to expand...
The wire that goes to D+ on the alternator from the bulb in the dash should have 12 volts on it when disconnected from the alternator with the ignition on, if you ground it, the bulb should light.
If you have no volts and the bulb doesn't light, either there is no 12v feed to the bulb, the bulb is blown or the wire from the bulb to the alternator is broken. You may have disturbed something when you did the ignition barrel.
 
Last edited:
policybuddy said:
ok, ignition off and alt plug unplugged, get nowt from the small bulb feed but both of the thicker brown cables giving just over 12v with no key in ignition... Not sure if I need to mention that for example the radio has always worked if needed with no key in ignition. the only other thing changed recently was the ignition barrel

many thanks
Click to expand...

both thick brown wires are battery fed so will be 12v at all times
 
Datatek said:
The wire that goes to D+ on the alternator from the bulb in the dash should have 12 volts on it when disconnected from the alternator with the ignition on, if you ground it, the bulb should light.
If you have no volts and the bulb doesn't light, either there is no 12v feed to the bulb, the bulb is blown or the wire from the bulb to the alternator is broken. You may have disturbed something when you did the ignition barrel.
Click to expand...

Thanks for taking a look...

With ignition on I do get 12 volts at both the alternator end and where the wire connects to the bulb on the instrument display..still no bulb lit and bulbs definitely good. My first thought was to run a new cable straight from the dash to the alternator but decided not to when I saw 12v at both ends...worth a try or a pointless exercise?


cheers
 
policybuddy said:
Thanks for taking a look...

With ignition on I do get 12 volts at both the alternator end and where the wire connects to the bulb on the instrument display..still no bulb lit and bulbs definitely good. My first thought was to run a new cable straight from the dash to the alternator but decided not to when I saw 12v at both ends...worth a try or pointless?


cheers
Click to expand...
duff alternator or earth
 
The Mad Hat Man said:
connect a jump lead between battery neg terminal and alternator case
Click to expand...


Morning, so just disconnected the smaller wirer from alternator and earthed to body turned key and light came on....does this tell me its the alternator or connection to it rather than the wire itself? Ideally id like to rewire the connectiong plug to the alternator before booking it in to be looked at...any idea how to get those old pins out of the plastic plug?

Cheers
 
That is what should happen. Ground wire to earth and light comes on. That is the exciter circuit on your Alternator. Means you alternator isnt being " switched on". Get a new one, or get that one refurbed.
 
The Mad Hat Man said:
That is what should happen. Ground wire to earth and light comes on. That is the exciter circuit on your Alternator. Means you alternator isnt being " switched on". Get a new one, or get that one refurbed.
Click to expand...


Great, ill book it in, it was only changed a year ago so part should be under warranty.. Many thanks again for your help
 
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