Battery charge LED fault finding

[rockthebus]

Hi Chaps and chapesses
My charge/not charging LED is not lighting up at all. I'm really struggling for time to delve into this (childcare, work and holiday in 3 weeks time to the Gower), but knowing that it also indicates whether the waterpump is turning or not I need to sort this.

Would some kind soul give me an ordered check list to go through, and including where to check (not brilliant with knowing where connections are made)?

Would really appreciate some info to help me focus my efforts.

Cheers

[Mocki]

Good evening
Assuming your battery is actually getting charge ?
Check the battery voltage with engine running at tickover is 14.5v ( between 13.8v and 14.1v)
If not check and / or replace brush pack on alternator
If all the above is ok,
check the actual LED in the dash pod.
Swap it for one of the others to test .

[rockthebus]

Thanks for replying, you've helped me in the past and not too far away!

I can hear the fuel pump spin faster once the revs have increased, so battery voltage is increasing but not checked the actual voltage..
The LED doesn't even illuminate on the 2nd click of ignition.

I wish I could remember how the voltage difference makes it light up!

[bigherb]

Remove the blue wire from the back of the alternator. Switch the ignition on and then touch the terminal end of the blue wire to the metal case of the alternator, the battery light should illuminate. If it does you have a fault with the alternator, if it doesn't then the fault is the wiring or the instruments.

[rockthebus]

Remove the blue wire from the back of the alternator. Switch the ignition on and then touch the terminal end of the blue wire to the metal case of the alternator, the battery light should illuminate. If it does you have a fault with the alternator, if it doesn't then the fault is the wiring or the instruments.

Thanks, that's just the starting point I need.

On a 1990 2.1, where does the rear harness join the main harness, ie will the blue wire have a joint somewhere on the rear bulkhead before it joins the main loom up to the clocks?

[bigherb]

will the blue wire have a joint somewhere on the rear bulkhead before it joins the main loom up to the clocks?

Yes in the junction box on the left of the bulkhead.

[rockthebus]

will the blue wire have a joint somewhere on the rear bulkhead before it joins the main loom up to the clocks?

Yes in the junction box on the left of the bulkhead.

Thank you

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[rockthebus]

So earthing the blue wire didn't illuminate the dash led. Checked the junction box in the lhs of the engine bay and buzzed the blue which shows continuity. So the problem must be after the ignition switch and before the loom to the back.
Any known hotspots?

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[marlinowner]

14 way connector to instrument panel is worth a look.

[adie89]

Did you swap the LED with a known other good one as suggested earlier? They do fail from time to time and 30 years I reckon fit ps the bill of enough time

[rockthebus]

Did you swap the LED with a known other good one as suggested earlier? They do fail from time to time and 30 years I reckon fit ps the bill of enough time

I ran out of time tonight. Is the a part number I can use at Maplin or similar?

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[Mocki]

Did you swap the LED with a known other good one as suggested earlier? They do fail from time to time and 30 years I reckon fit ps the bill of enough time

I ran out of time tonight. Is the a part number I can use at Maplin or similar?

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just swap it with one of the others in the cluster for testing purposes, any except the blue main beam, which is not a led, but a bulb *
any non high density led will replace it , just observe the polarity, the flatedge of the dome is the neg leg

*blue leds were not invented when the t25 was in production, so its a bulb unless someone has fiddled before you

[rockthebus]

Did you swap the LED with a known other good one as suggested earlier? They do fail from time to time and 30 years I reckon fit ps the bill of enough time

I ran out of time tonight. Is the a part number I can use at Maplin or similar?

Sent from my SM-G930F using Tapatalk

just swap it with one of the others in the cluster for testing purposes, any except the blue main beam, which is not a led, but a bulb *
any non high density led will replace it , just observe the polarity, the flatedge of the dome is the neg leg

*blue leds were not invented when the t25 was in production, so its a bulb unless someone has fiddled before you

Brilliant. Just been to the DT faculty in school to get a couple

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[rockthebus]

So swapped out the led for the oil led and no change. Checked the charge led in the oil socket and it works.
So what next?
I know on the good old days of bulbs, that they would illuminate when the voltage difference disappeared. Is this still the same?
So should I see alternator voltage on the blue wire in the 14 pin dash connector?
Any other advice would be great
Thanks

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[bigherb]

So should I see alternator voltage on the blue wire in the 14 pin dash connector?

Yes when the engine is running