Hello,

What is the best way to rig up (easily and cheaply) a cigarette lighter socket (for lights, phone chargers etc) that doesn't go off when the ignition goes off.

Is there a common positive cable that is readily accesable? Whats the best earth inside the car?

Also, is there a one - way diode or such in the dash mounted socket? If I leave a battery connected to the socket, will it effectively flatten it when I turn the ignition off? I'll check with a meter.

Any replies (esp to the first point) much appreciated.

John

> Also, is there a one - way diode or such in the dash mounted socket?

> If I leave a battery connected to the socket, will it effectively

> flatten it when I turn the ignition off? I'll check with a meter.

Definitely check for this. In my '89 244, the backlight on the radio's display will glow dimly if I leave one of my battery-powered devices connected to the dash socket with the ignition off.

To avoid this, a diode is needed somewhere. I didn't check the wiring diagram to see if one should be connected to the dash socket. Even if Volvo included a diode, the previous owner of my car did some creative wiring, so no telling what the circuit really is.

To be fair, the designer of my portable device should have thought of this scenerio and avoided trying to power a car with a small 6V NiCd pack.

Hi Ron,

There are no blocking diodes, but the cigar lighter and the radio share fuse #1 if I recall correctly. Someone makes a "service tool" that works like your accessory does: A nine-volt battery connects to that jack to keep the microprocessor in those later model radios from thinking it has been thieved if you should disconnect the car's battery. I hope the service tool has a blocking diode in it.

John --

"...that doesn't go off when the ignition goes off..."

Using a test light or voltmeter, survey your fuse panel. You'll find that the fuses cluster into three categories. First, some fuses are powered with the ignition switch in the "acc" position. Second, you'll find more fuses that are powered in the "run" position (and the first group are still powered). And finally, you'll find a group of fuses that are always powered even with the key off and out. These are for things such as the interior light, brakelights, clock, and a few other accessories.

Some of these fuses may not be used or are very lightly used. You should be able to move the female connector (that goes to the lighter socket) to one of these "lightly used, always powered" fuse tabs.

Be sure to note which fuse now supplies the lighter. Be sure to install a fuse of adequate capacity.

Also -- AND THIS IS IMPORTANT -- be sure to disconnect the battery ground cable before you start probing around the fuse panel. You might otherwise short an unfused wire to ground and burn up your car.

> Also -- AND THIS IS IMPORTANT -- be sure to disconnect the

> battery ground cable before you start probing around the fuse panel.

> You might otherwise short an unfused wire to ground and burn up your

> car.

Thanks Don and Everyone else.....

I just want to clarify though, how do I test for a closed circuit (ie voltage) at the fues panel? do I place the probes either side of the fuse? How can I measure voltage with the battery disconnected?

No doubt I'm missing something obvious...

Thanks again,

John

"...how do I test for a closed circuit (ie voltage) at the fues panel? do I place the probes either side of the fuse? How can I measure voltage with the battery disconnected?"

Good questions.

First, use your voltmeter with the negative probe attached to a solid and reliable ground, and use the positive probe to measure voltage on each side of the fuse at the fuse clip. As much as possible, do this with the circuit active. That is, with current flowing through the fuse. A perfect fuse (and clips) will show no change in voltage from one side to the other, whereas a crummy fuse and/or corroded, high resistance contacts will exhibit voltage drop. In this case, for example, you might see 13 volts on the "high" side and 9 volts on the "downstream" side of the fuse. This would require immediate attention. (You'd probably also raise a blister if you touched this fuse.)

You could also measure the drop directly across the fuse (by touching the fuse clips with the probes). In the above example, a perfect fuse would show 0 volts drop whereas the crummy fuse would show 4 volts drop.

Finally, make your measurements with the battery connected and able to turn on various loads (wipers, lights, radio, and so on). Once you've "mapped out" the fuse conditions (keep notes of your measurements) you disconnect the battery and dig into the fuse panel with a wire brush, sandpaper, etc. to clean up the fuse clips.

Because you're trying to reconnect the lighter to a different circuit, you'll be moving connectors among fuse tabs, probably using needle-nosed pliers. You do this with the battery disconnected.

The "downstream" side of the circuits (or after the fuse) is the end toward the inside of the car, nearer the driver's knees.

"Using a test light or voltmeter, survey your fuse panel. You'll find that the fuses cluster into three categories."

Last night I was doing this probing on my '84 to discover perhaps a sub-category of "power when key is inserted, any position" which seemed to work out well for the 50mA drain of the voltmeter I was adding. Had an empty faston lug and not much more than the key reminder buzzer as current, ahem, occupant. If my memory is working today, it was fuse 4 on the '84.

Ground (by flashlight) was much more difficult. Resorted to using the 6mm bolt attaching the heater unit to the floor, where two other existing grounds were.

So far, it seems like a good place for the voltmeter because you can see the battery voltage before, during and after cranking without a glitch while you switch.

It might be OK for low current accessories, say through an 8A fuse, but I've seen the contact assembly in the ignition switch that provides this function-- it is not nearly as hefty as the other switches. So if I move my cigarette lighter socket and want this switching, I'll use a relay.

In years past, I've done a LOT of probing and digging around the stupid 240 fuse panels. These damnned things seem to be an engineering design afterthought (as opposed to afterbirth). I lean heavily on the schematic -- it shows the fuses clustered into three groups (at least for the late-'80s and earlier cars). These groups are the:

1. Always powered
2. powered in "acc and run" position
3. and powered in "run" position.

Hi Don,

The way you dismiss the careful design of that fuse panel! (I looked, it doesn't say Lucas on it anywhere.)

Normally I'd have gone to the schematic to properly plan something like this, but the connection of my voltmeter was a little rushed. It is fuse 4 that provides power in the 4th "subcategory".

"I have not seen any fuse associated with the "chime" circuit or starter-motor-cranking position, although the '90s cars might have this."

You'd have to look in one of your pre-85 cars. Check this out, as I have only one car that qualifies as a '90s car. According to Bentley's reproduction schematics, fuse 4 is used to power the tank pump in those '85-'93 models using re-solderable fuel pump relays.

The schematics reproduced in the Bentley for '83 and '84 show fuse 4 has power from contact "S" of the ignition switch in US cars. Haynes drawings suggest it has been this way since at least '76.

I suppose that gives us a new 4th "subcategory" in those later model years -- a fuse that is powered only when ignition pulses are being provided to the coil. A place to put that jumper wire when you forget to Fosterize your bride's fuel pump relay.

Back to the chimes.

Ignition switch terminal "S" is used for the chime that reminds me to turn off the headlamps and remove the key. Les Lyne motivated me to dissect an ignition switch in his quest to redraw the Volvo diagrams, so I have intimate contact with this contact-- it is not much of a contact.

The chart shows this switch is closed while the key is in place, or in the terms of the chart, position 0, 1, 2 and 3. Haynes drawings suggest it has been this way since at least '76.

So, if your 240 is pre-85, you should be able to wire accessories to fuse 4 if hot-when-key-inserted is desireable. I wouldn't change the 8A fuse to anything higher, though, based on the looks of the ignition switch contact and its making force.

Thanks Don,

I ended up using fuse #9 - hazard lights.

Works like a dream.

not too "hazardous" either.

John