alternator light not working

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Al Housman
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alternator light not working

Post by Al Housman »

1990 diesel doka.

Starts fine but no battery illuminated on the dash. The battery is discharging quite rapidly but it may be getting past its best.

Would anyone have any useful pointers please?

Could it be a blown bulb?

Thanks

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Mocki
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Re: alternator light not working

Post by Mocki »

First thing to check is the small blue wire at the rear of the alternator , check it is connected and is not damaged 
it’s should when it is disconnected from the alternator, with the ignition switched on give you a reading of about 12v against chassis neg .
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Robsey
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Re: alternator light not working

Post by Robsey »

What he said.

Chances are, you have a dodgy connection or wire.
It is indeed a blue wire.

The route is not too convaluted.
Alternator to the engine bay junction box.
Junction box to main fuse box.
Then main fuse box to dash panel.
And then there is the dash flexible circuit board.

These flexible circuit board tracks can crack and fail with age and brittleness. So could also be the cause of your dead warning light.

The dash light is an LED , so not a normal bulb.
LEDs have a much longer life span, than normal bulbs, so not as prone to burning out if used normally.
Last edited by Robsey on 07 Apr 2021, 20:50, edited 1 time in total.
1983 Tin Top with a poorly DF and 4 speed DT box.
Soon to have a whizzy 1987 DJ.

davidoft1
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Re: alternator light not working

Post by davidoft1 »

Put a multi meter on the battery , then start the engine , if the voltage doesn’t increase by 2-3 volts the alternator isn’t charging, check the dash light works , then as above check the alternator wiring

Al Housman
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Re: alternator light not working

Post by Al Housman »

Many thanks all of you for responding so quickly. I’ll be having a poke around today.🙂

Al Housman
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Re: alternator light not working

Post by Al Housman »

As suggested the blue wire had come adrift. Eventually found the correct connection and red light comes on then goes out as it should.

Only additional question: where does the red/black wire which is lying next to the blue one go as it is also disconnected? On the digram it just goes to the alternator but it's not clear where.

Thanks
again

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Robsey
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Re: alternator light not working

Post by Robsey »

My understanding is that the red / black wire is the starter solenoid wire.
So it should go to the starter, not to the alternator.

Heavy red / black goes from starter motor directly to fusebox connector D24.

Connections to -
alternator are as follows: -
10mm red wire to starter motor.

1.5mm red wire to engine bay "engine electrics"
(Fuel injection systems, pre-heaters etc).

0.5mm blue wire to fuse box pin E13.

Earthing is through the mounting brackets.
------------------------------------------------------

The starter motor is as follows: -

6mm red / black wire is from the solenoid to the fuse box pin D24

10mm red wires is to the alternator.

70mm red wire is from starter motor to the battery + post

Both the starter motor and starter solenoid, are earthed through their mounting to the bell-housing.

-----------------------------------

I hope that helps.
1983 Tin Top with a poorly DF and 4 speed DT box.
Soon to have a whizzy 1987 DJ.

T25boy71
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Re: alternator light not working

Post by T25boy71 »

Have you checked the alternator is actually charging the battery properly as I thought the light on the dash was an indicator of not charging You may just have a worn out alternator.
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Robsey
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Re: alternator light not working

Post by Robsey »

Al Housman wrote: 10 Apr 2021, 18:06 As suggested the blue wire had come adrift. Eventually found the correct connection and red light comes on then goes out as it should.
1983 Tin Top with a poorly DF and 4 speed DT box.
Soon to have a whizzy 1987 DJ.

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shrig1969
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Re: alternator light not working

Post by shrig1969 »

I'll jump on the back of this if i can....
I also had similar issues this weekend with the alternator not charging the battery, but having read this and a couple of other threads from you knowledgable lot I managed to get it sorted.
Having spent most of Saturday trying to sort, ordering a voltage regulator from Brickwerks and checking my bank account in case a new alternator was required I gave up and trawled the forum.
Sunday morning I began again but in a more organised manner. 12.5 volt reading at the battery 12.5ish at the alternator. 
Then the blue wire connection on the back of the alternator with ignition on. Nothing.... no voltage and no battery light on dash.  I tried a continuity check from crimp connector to the connection in the black box in the engine bay but again nothing. Everything looked ok with no visual damage? Crimp was clean and secure I thought!
I cut the crimp off and tried again from bare wire to black box and hey presto I got a reading ( bleep )
Re-crimped and re-connected blue wire, ignition on and battery light appeared. Started her up and immediately got a charging reading of around 13.9 v.
Started the weekend thinking of being ££'s out of pocket ended up costing about 2 pence on a bloody crimp  :ok .
Hopefully this will help someone else in the future.
Thank you all.
I am no mechanic, but I try......
1987 1.9DG Hi top 4 speed manual

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