Volvo instrument panel - help needed

[Bobc]

I have the standard Volvo panel (two buttons, rev counter, lights and key switch). Does anyone out there have knowledge and experience of these?

I have a problem with mine in that I have the oil and battery lights always on (at about half the normal brightness) when the battery is connected.

When I turn the ignition on, they come on at full brightness, but once the engine is started, they go back to half brightness.

Something is obviously delivering a small amount of power to these lamps permanently, but I can't work out what.

Are ther any know faults that cause this, such as faulty switches, relays, etc.?

 

[Muxey]

possible bad earth ?

 

[cpedw]

This circuit diagram of the alarm panel was posted here some time ago. The notes below were compiled by me from the same thread. It doesn't describe faults but the explanation might help to work out your problem.

How the Volvo Alarm Panel works.
The alarm goes off if you press the test button or if you have an oil pressure or water temperature fault with the alternator giving output.
The diode in the water circuit to alt. tests the bulb when you switch on: the water light earths through this diode to the charge warning light line. This is why the water light as well as the charge light come on if you have a charging fault. The oil light self tests by earthing through the normally closed oil pressure switch when the engine is not running so doesn't need this diode.
Low oil pressure sounds the buzzer provided the alternator is working. If you have simultaneous alternator failure and low oil pressure, the lamp will light (all 3 in fact) but the buzzer won't buzz.
If you have an alternator fault both the charge and water lights come on.
When you turn on key, all 3 lights should come on. However the water temp light connects via the 61 lead, not via the water temp switch. This gives you a parallel excitation feed if the charge warning light bulb has failed.
When you crank/start, the oil light should go out as soon as pressure is produced. The water temp and charge light will go out almost simultaneously as the voltage rises (the water light will be dimmer and may go out fractionally first as it has an extra diode in its circuit).
If the alternator fails with engine running, water and charge will both illuminate. The handbook tells you this. (It's about all it does tell you!)
If the brown wire from the panel to the alternator (61 or D) is broken or if the alternator has an internal fault in the regulator or brushes or field winding and no continuity to earth, then neither the charge nor water light will come on when you switch on. If you earth that wire, both will come on. If you earth the water temp wire (that's no 3) only the water light will come on. The water light not coming on when you turn on does NOT mean the water temp switch is faulty. It means the 61 wire or the alternator has a fault somewhere!!
The buzzer will never go off for a fault if the alternator isn't working (although it will still work if you press the test button). If the alternator is working, the buzzer will sound for oil pressure or water temp.


Derek

 

[scottie]

Try disconnecting the loom and spraying with water repellant
Damp can cause leeching

 

[Bobc]

The trouble is that I don't know what the switches and relays all do. In the wiring diarams it just lists the as "switch" or "relay" (really helpful).

It all seems to be working as it should, other than this faint glow that I get from it when the ignition is off, or when the engine is running and all the lights should be off. So if it should all be off, then surely it can't be an earth leak can it? I was assuming that it's getting a bit of voltage when it shouldn't , possibly though a faulty switch or relay not closing properly.