Looking for a switched circuit to add a light and thought the lighter would be a place to start. Probed the connector and found .61 volts with ignition off, fine when switch turned on. Scratched my head and figure I'd get some advice, so my question is why is there any voltage when ignition switch is off?

 

Where'd you find the circuit that had the voltage? What kind of light are you looking to add? Switchable by toggle or by power?

From what I recall, the lighter isn't a 12V constant, it's a switched circuit... Course, I think that was why I pulled mine, to begin with.

Check the fuse box. With the car off, your source lead will show +/- 12V, and mostly constant with the car running.

 

DMM
Power for an AutoMeter Shift Llight
Yes, lighter should be a switched circuit as it has never had power with the key off, at least not 12 volts, in the 21 years we've owned the car.
I'll start back at the fuse box out of curiosity, but the .61v is why I'm confused. I also have 3 other meters, one a Simpson, so I'll double check using them.

Thanks for the reply

 

my sweat puts out .61v... seriously.

 

Might pull the CIGAR fuse on the ACC buss and see if the voltage is still there. Shouldn't be anything there with key OFF.

If stk I'd bet you could take that wire and put it to gnd and nothing bad will happen other than the .61 disappears. It might be a capacitor or some such thing in the radio.......logicon......pwr mirrors (anything item on the ACC buss).

Worst case would be the CIGAR fuse blowing. NOT very likely to happen at all.

 

All stock, at least the wiring. I didn't believe anything would happen with the .61v but was just curious as to what might be the cause. As I've had the car for 21 years, who knows how long it's been this way.

The electrical guru from Texas has given me a few items to check.

Once again thanks for the replies.

 

if i recall, i tapped the illumination wire from the climate control, just probe wires off it til you see one that changes with the dimmer, that way you have dimmer adjustment on your gauge.

 

Once again, thanks. When I installed the mechanical boost gauge many years ago, I did run the wiring from the light wire on the back of the lighter.

 

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Good point out, Hailers! That was going to be my next suggestion.

As far as .61v, sounds like something's bleeding current; mild short, or something grounding out, just enough, to show.

 

Either that, or it is just a ghost reading. Pull the fuses, and if you still read voltage it is just ghosting. I can hold both probes of my DMM in both hands and get a voltage.

 

^+1

Good point.

 

As soon as the DMM is removed fromn the connector the reading drops to 0, touch the connector and it's back to .61V.

I was out of town today, so it looks like some investigation Thursday/Friday.

Far from an electrical genius when it comes to the car systems. so thanks for all the replies and as was out of town today, looks like some investigation will take place Thursday/Friday, or when I get some free time to get to the garage.

 

Either a ghost reading or some kind of Fuct ground reading.

 

If you pull the CIGAR fuse, then that circuit will not be connected to the source of power for the ACC buss in the interior fuse box.

But it WILL still be tied to the other circuits that are powered by the ACC buss. Those would be outside mirrors, clock, logicon and radio. They should also be dead if the CIGAR fuse is pulled unless someone wired something in to them from and unauthorized source after the car was built.

A couple of those items above also have pwr from other busses for other functions than the ACC functions. Like the warning light unit gets pwr from the ACC for the clock but other items get power from another fuse. Might unplug each of those other items til the half volt goes south.

Can't bring myself to put a meter on my cars to see what is normal and what is not.