Alternator Problem

RoadrunnerA65 · Apr 16, 2014

Has anyone any suggestions on how to solve my alternator problem. My old alternator was electrically fine (bad bearing) type Lucas LRA356 (45A). I wanted to uprate to 65A so bought a Lucas LRA406 (type133) on fitting the ignition light would not come on. Refitting old Alternator everything works fine. Lucas say it should work and dealer says he has tested item and its ok. What is the problem? any ideas?

trax · Apr 16, 2014

you are fitting it wrong?

take it off and look for the markings.

B+ to battery via starter, thick brown wires

d+ to dash light, thin brown/yellow stripe

you don't have a tacho, so not w for you

Vincemcdonald · Apr 16, 2014

For an alternator to begin working it requires a small supply of current called the exciter current. This comes from the battery, through the warning lamp in your dash (which illuminates and acts as a resistor) to the alternator via the thin wire.
When the alternator starts producing current the lamp in your dash will go out. This is because it now has voltage both sides of it so no flow of electricity so no illumination.
So I sounds like that your new alternator is not receiving it's exciter current. You have proved that the lamp hasn't blown so you must have a wiring issue at the alternator or your new alternator is faulty.
Maybe you could take it back to the dealer and whitness his alledged test.
By the way. The SAD landrover club has a laning day very close to you on Saturday. If you're not a member you can join on the day. Go to sadlrc.co.uk for details.

Cheers, Vince.

trax · Apr 16, 2014

Vincemcdonald said:
For an alternator to begin working it requires a small supply of current called the exciter current. This comes from the battery, through the warning lamp in your dash (which illuminates and acts as a resistor) to the alternator via the thin wire.
When the alternator starts producing current the lamp in your dash will go out. This is because it now has voltage both sides of it so no flow of electricity so no illumination.
So I sounds like that your new alternator is not receiving it's exciter current. You have proved that the lamp hasn't blown so you must have a wiring issue at the alternator or your new alternator is faulty.
Maybe you could take it back to the dealer and whitness his alledged test.
By the way. The SAD landrover club has a laning day very close to you on Saturday. If you're not a member you can join on the day. Go to sadlrc.co.uk for details.

Cheers, Vince.

lol, what a name

RoadrunnerA65 · Apr 17, 2014

Thanks for the replies, I now understand a bit better how the light works. I'm sure it's connected correctly. It's difficult to get it wrong because the B+ brown wires have 9.5mm twin spades and the D+ has 6.3mm spade. Continuity and earthing all checked out as ok with multimeter and engine harness is almost new genuine LR part. So it looks like an alternator fault despite what the supplier says.

trax · Apr 17, 2014

RoadrunnerA65 said:
Thanks for the replies, I now understand a bit better how the light works. I'm sure it's connected correctly. It's difficult to get it wrong because the B+ brown wires have 9.5mm twin spades and the D+ has 6.3mm spade. Continuity and earthing all checked out as ok with multimeter and engine harness is almost new genuine LR part. So it looks like an alternator fault despite what the supplier says.

turn ignition on, stick d+ dash wire to earth.. the light should come on.

get your multi and stick cont on d+ alt and the other end to your engine block and it should beep showing a circuit.

if you don't get a circuit, then try sticking a jump lead to the alt housing and another to the block. if that makes it all work then for some reason your alt isn't being earth via the casing

Alternator Problem

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