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Old 05-01-2013, 12:33 AM
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Parasitic voltage loss

I have around a 200ma load when my car is off. Drains the battery. 1970 Cadillac Hearse.

I narrowed it down to the circuit in the fuse box labeled lighter/clock/body. I've checked the dome lights, (they're on that circuit) and one had some melted wires. I replaced them, but I don't think that would cause a draw, since there is only power going there when the door is open. The stereo is on that circuit, but that draw shouldn't be 200ma. But the draw is there when the radio is unplugged too. And still there when the clock is unplugged. There is nothing else added to the system, and there are no other cut, or broken wires. I've jiggled every wire under the dash, and in the engine compartment to check for a loose connection, but no change.

What am I missing?
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Old 05-01-2013, 01:38 AM
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Bad grounding will cause drain. Connections dirty wiring frayed on the outside and /or on the inside of the threading. I had a major drain starting a year after getting the truck. Symptoms were of the alternator, double checked everything replaced it. A year goes by battery bites the dust ok its over expired buy new one put in. A couple months later symptoms of alternator again. What the crap...rechecked everything again..every fuse line connection in the entire truck then replaced the alternator. Following year battery issues that whole year...recharged the battery 4 times that year until it was toast. Ok ive had enough even though I trusted my conclusions with checking everything I did it again except did it the easy way. Replaced every line and rechecked fuses one by one on each line. Put new battery in and found out it was the main grounding cable being rotted from wetness running down onto the battery then followed the line all the way down to the alternator and chassis. The factory location had the battery right under the hood/fender channel so I moved it further in and the relay box is pretty near to the same channel and bothers me but no where else to put it ......right now anyway.
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Old 05-01-2013, 03:28 AM
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You also have power to dome lights all the time. It works differently than most other circuits because the ground is switched and the power is constant. The wiring is always powered and the door switch grounds the circuit when the door is open.

You might want to check the grounding switches on the door. They are very simple switches, but have been exposed to the elements over the years because they are outside the door seals. Corrosion may have built up between the barrel and the body of the switch (its mostly just one spring-loaded tube inside another) and current is following the path of the corrosion even when the switch is compressed (the off position).

You will have to unscrew the switches and then remove the wires to disconnect them. Usually the back of the switch is inside the two walls of the kick panel and not reachable from inside.

Bruce
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Old 05-01-2013, 03:33 AM
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X2 with GMC, Bad ground
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Old 05-02-2013, 01:44 AM
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Ok, yeah 75gmck25, that's what I thought too at first, about the dome light, but for the rear, the wire at the switch is power (+). When the door is open, the switch closes and then power goes to the lamp. The other side of the lamp is grounded at the mount for the receptacle. Usually it's a ground at the switch. And when the door opens, the switch grounds one side of the lamp, and the other is power. All of my other cars are that way. The Nova, the Firebird, the Elcamino, the Tahoe, the CRX, the Civic and so on.
Maybe they did this for a reason. I don't know. But the door switches are rocker type, with two terminals. Not the regular door pin with one terminal (plunger type) . And I need to replace at least one and I don't know where to get them. There are three dome lights in the rear like this. And there are three switches. One for each door.

The front I believe is normal. I haven't had a chance to check it out yet, but I pulled the dome lamp out, and there was no grounding wire on it. There were two wires coming to the receptacle, but one broke when I was messing with it. The front dome light, and under dash lights don't work. So that's why I was messing with them.


And itsjusti, about the ground, I haven't removed and clean it yet, but when I was looking at it, it seemed to be good. No corrosion or anything. Nothing on either the ground wire, or the positive cable. Nothing at the alt. either. I pulled the wires out of there first, and the regulator. But I traced the load to the circuit for the body/lighter/clock when I was pulling fuses. So something there is wrong.

Does anyone have a service manual? I need to know where this circuit goes. What does it connect to? 1970 Cadillac Superior Hearse end loader.
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Old 05-02-2013, 01:48 PM
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I also agree that it could be corrosion causing a weak short in one of the door jamb switches, but with a 200 mA parasitic draw my first suspect would be the glove box light. Just for kicks, you might want to remove the glove box light bulb and see if it affects your amp reading.

Good luck.....
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Old 05-02-2013, 04:44 PM
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A bad ground would be defined as a poor connection or connection impeded by high circuit resistance. Cause is irrelevant . Corrosion, rust, broken ground strap...etc.

A bad ground will not cause a parasitic draw. A corroded door switch is actually a short to ground if it is conducting voltage
The glovebox light is a great suggestion.
A cigarette lighter in the back seat, that is rusty from years of moisture/non use etc can cause a drw if the rusty particles fall acroso ts the positive connecotr in the socket.
The Body fuse may also supply constant voltage to the HVAC controller which could be defective and also if it has the" Dial" auto temp system the blower module under the hood can also cause a draw.
Seems to me there are some other items on the "body" fuse. I just cant remember what they are.
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Old 05-03-2013, 12:25 AM
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JoeG: "the glove box light. Just for kicks, you might want to remove the glove box light bulb and see if it affects your amp reading."
When I was checking the front, IE: lighter in the ashtray, stereo, clock, I checked the lamp in there. But there is no lamp! What? There is a hole, and a plunger switch, but no lamp. So I looked for it, and couldn't find anything. No socket, no wires!??!

LATech: "A cigarette lighter in the back seat, that is rusty from years of moisture/non use etc can cause a drw if the rusty particles fall acroso ts the positive connecotr in the socket."

There are no lighters in the rear. Most dead people don't smoke, well, anymore at least!

"The Body fuse may also supply constant voltage to the HVAC controller which could be defective and also if it has the" Dial" auto temp system the blower module under the hood can also cause a draw."
Also, there is no A/C. There is a heater, and I pulled the connector for the fan, and checked that too, but it has it's own circuit.

I'm trying to think of what else could be back there. All of the wire under the dash look perfect. There is some minor corrosion on the terminals for the fuses, but nothing on the connectors. Like the bulb sockets, or the column harness. But those are on different circuits too.

There is only like 10 or so circuits in the fuse box, but only this one has the draw. If I put the leads of the DVOM to each terminal for the fuses, I get the same draw as I do with the negative battery terminal.

Oh, one more thing. If I connect the black (-) lead to the battery cable and the red (+) lead to the battery, it shows nothing. The other way it shows the draw. (or was it the other way around?) Shouldn't the draw show the same both ways? Either way, there is a spark when connecting the cable to the terminal, or when replacing the fuse for that circuit.
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Old 05-03-2013, 10:13 AM
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easy test

One way to test for this is to connect a 12 volt test light across the fuse clips, with the fuse removed. The light should light at nearly full brightness.

As you attempt to find the fault (wiggle wires etc.) you can view the light. And as you find a possible trouble the light may change brightness, blink or go out.

This may help you find the trouble.

vicrod
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Old 05-06-2013, 04:30 AM
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Ok, connected test light. It lit very dim. jiggled wires everywhere. No change in brightness. Opened rear door. Light got very bright. Closed rear door, light slowly dimmed. Messed around with front door switches. Light dimmed out. Stayed dim. Kept checking different wires. Light stayed dim.

Does anyone have a wiring diagram for this car? Or at least for a 1970 Caddy? I started pulling apart the dash to see if there was anything amiss, and there was some weird stuff. The thing is that none of it was on this circuit. But I don't know if the wiring was changed when it was built. So if I can get an original diagram, I could go from there.
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Old 05-06-2013, 04:24 PM
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A lot of these specialty vehicles (Hearses, Ambulances, Motor homes, School buses, etc) are wired the way someone felt like doing it that day and there may not be a wiring diagram for it. Your door switches may have come from the cheapest vendor who's been out of business for years and you may never find the exact replacement. One way to locate the problem, is to find the wire feeding the interior lights and cut it to see if the problem goes away. This will narrow down which direction to search and you can just splice the wire after you fix the problem.
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Old 05-06-2013, 04:40 PM
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Try finding the connector that connects the rear door circuit to the body circuit......... opening and closeing the door might stretch the wires and over time, cause them to chaff etc.... If you can locate the connector unplug it and see if the problem goes away....... Never worked on a hearse before but vans and SUVs that have a rear opening hatch often have a problem with wires in that area.
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Old 05-07-2013, 02:21 AM
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sparkchaser: "wired the way someone felt like"
That may be, but there is a master harness that they go by and someone hopefully has that.
"Your door switches may have come from the cheapest vendor who's been out of business for years and you may never find the exact replacement."
Maybe, but there has to be some kind of replacement. Also, it's not like it's different from factory. They have an oval mount that has two screws on each side. That's factory, right? I could be wrong. I had read another post somewhere about a guy with a regular Cadillac with the same type of door switch as mine.
I have seen that there are some push button type, two terminal switches that might work. http://reoriginals.com/ProductImages/N0076X.jpg
http://www.opgi.com/common/CE12195-lrg.jpghttp://img0103.popscreencdn.com/1606...mb-switch-.jpg

"find the wire feeding the interior lights and cut it" I hope it doesn't come to that.

EOD Guy: "opening and closeing the door might stretch the wires" Luckily, there are no wires in the door. Just to the switches, and lights. The wires are inside the body.

If I can get a diagram, it could help to know what colors what wires are. Does anyone have any wiring diagram for any GM model in the late '60s or early '70s? GM had a standard. My '81 Elcamino had a lot of the same wiring as my '73 Nova and my '82 and '88 Firebirds. Anything at this point will help. I'll also see if I can come up on anything from my Nova manual.
I have the knee panel off to trace wires, and can see pretty much everything from there. I am planning on putting an amp and some speakers in the rear, so I will be taking off the door sills and such to run the wires. I can check more then, but I'd like to know what wires do what.
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Old 05-10-2013, 06:19 AM
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Might be a ghost drawing energy. They want to connect with you. Do a exorcism on the Caddy, keep some holy water in it also. I'm sure this is the problem.

Last edited by dogwater; 05-10-2013 at 06:27 AM. Reason: more info
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Old 05-10-2013, 03:20 PM
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Speaking of ghosts, John Edwards or one of the other Mediums can help.
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