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Enes
Enes, VOLVO Master Technician
Category: Volvo
Satisfied Customers: 4911
Experience:  18+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
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Battery and oil pressure lights stay on, even with key out

Customer Question

Battery and oil pressure lights stay on, even with key out of ignition. Alternator output is great with vehicle running, and battery tested ok (though it was weak from being drained by the battery and oil pressure lights staying on). Problem occurred suddenly two-three days ago for my customer and has been an issue since.
Submitted: 1 year ago.
Category: Volvo
Expert:  Gary replied 1 year ago.

Hi Greg,

I would say the alternator has battery feed on the warning light wire.

Do the lights go out if you disconnect the warning wire at the alternator?

Gary

Customer: replied 1 year ago.

I will check tmrw morning and let you know..which wire would this be?

Expert:  Gary replied 1 year ago.

Hi Greg,

Disconnect the small wiring connector at the back of the alternator, would have two wires in the connector.

If the 2 lamps go out, the fault is within the alternator.

You'll then need to replace the alternator.

Gary

Customer: replied 1 year ago.

only have main b+ wire and exciter wire attaching to the back of my alternator. Disconnected exciter wire and lights stay on

Expert:  Gary replied 1 year ago.

Hi Greg,

I would say there is a foreign voltage on the exciter wire while it is disconnected.

Are the 2 lamps normal brightness or half brightness?

Can you place a multimeter on the exciter wire while it is disconnected to measure for foreign voltage?

Can you disconnect the oil pressure switch to see if the lights go out?

If there is a foreign voltage, can you then disconnect the cluster to see if the foreign voltage goes away?

I was hoping for you, the fault was in the alternator.

Hope this helps.

Gary

Gary