Greetings - I took the instrument panel out of my Volvo '86 240DL wagon looking for disconnected wires. Now when I tried to put it all back together I don't get any readings! At all. I've got three hot wires but they don't do anything.

On top of that a wire from the alternator has melted it's insulation - so I disconnected it - where that wire connects to the alternator doesn't put out juice . . .
and another wire to the nearby oil pressure or temperature guage also melted it's insulation so I disconnected that.

I'm in escape mode from zombies and perhaps only immediately need to be sure the temperature guage is working so the engine doesn't cook - so perhaps I could try to hot wire this circuit?

A friend mentioned relays from the fuses to the wires that actually touch the instrument panel. Could these need replacing?

The car starts right up and runs fine except for this. Thnaks! Dagaan

 

If you want your alternater to charge the battery, it must be connected through the battery light in the instrument cluster. If it isn't connected, no charge.

Are these wires actually melted or is the insulation crumbling on them? Your car is in the years that had biodegradable wiring harnesses. The insulation on the wires degrade over time (heat accerating the process) causing all kinds of issues. If the wires melted it is because there is some sort of short somewhere in the wiring harness. These need to be chased down and fixed.

 

Hi - Thanks for the reply. OK got it about the loop from the alternator through the dash 'battery charging' guage.

And no, the wires are not melted but only the insulation completely vaporized. The insulation being biodegradable makes sense.
However - the instrument panel WAS working with the wires in this state! I had gas guage - can't remember about the alternator - temperature - a few of them.
But now nothing. YET there are three wires that are running 12 volts so you'd think something would light up?

With appreciation, Dagaan

 

If I remember correctly, power comes into the instrument cluster on one of the 3 wires that connect to the speedometer. From there, power is transferred to the cluster circuit board via a u-shaped wire clip that has no insulation and then goes through what looks to be a flexible plastic circuit board that is attached by two screws. This flexible circuit board is actually a fuse. Check that to see if it is blown.

 

that sensor on the exhaust side of the block is your oil pressure light. and yes, the wire to the alternator is the D+ 'bootstrap'. when you switch on your ignition, that wire is powered via the alternator light on the dashboard, this provides the initial magnetic field for the alternator to start generating juice.

 

My computer's been malwared so it's hard to get around just now. Thanks for replies.
Pierce - can I connect the alternator light on the intrument panel directly to the secondary connector on the alternator? The insulation is all worn on two wires - that touch and that disappear into a multi wire tube -.

Correct that the activating wire connects to the speedometer - got that and also the temperature and gas guage going.

Thanks!

 

the circuit goes like this...

[battery +]-----[ignition switch]----[instrument panel batt light]------[D+ on alternator]

I don't have an 86 wiring diagram, just 1985 and 1987/88. the 85 was mechanical speedo, the 87/88 (and later) are electronic speedometers, so they are different. yours is probably identical to one or the other.

on a 87/88 240, the battery light output is a red wire from instrument panel connector 31 pin 11. connector 31 is the full circle connector, pin 11 is near 6:30 as you look at the back of it. a 1985 240 is the same.

on the 87/88, the alternator light power connection at the instrument panel is a red/black wire on pin 3 of connector 233, which is the 3 pin speedometer connector. that is connected to the ignition switch.

on the 1985, the + connection is a blue-red wire to the 'smile' shaped connector pin "A", which comes from fuse 13, which comes from the ignition switch and to the battery.



your battery light should turn on when you turn the key to II (run), that indicates there's boostrap current going to the D+ on the alternator. when you start the engine, the alternator light should go out indicating the alternator is charging the battery.

 

Thanks Pierce - Just what I wanted - the sequence of connection events. For your pretty complete records, my '86 240DL has the electronic speedometer.

Thanks! Dagaan

 

Looking over your old response on electrics. Thanks for this.