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Electrical nightmare

1350 Views 28 Replies 7 Participants Last post by  jn.mitchell59
Helllo again. This time, Im at a complete loss. I've spent hours trying to find out why my tempgauge, fuel gauge, shift display, & radio stopped working. Also the charge light is still on, even though it's charging. (The shift display quit about a week before the other stuff did.) I've checked ground points, avd all fuses great and small with an ohmmeter, and pored over diagrams searching for a common point that would tie all this together. I'm considering calling the Belle of Louisville, to see if they need a new boat anchor! Help, pls!!
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dang, and you just got that fuel gauge sending unit working too. Aside from the radio not working, I would think the bulbs could have gone out. I guess you don't mean bulbs though.
I'm assuming you have an analog dash. The only common point I can think of without looking over diagrams is the ignition switch / circuit. It would have to be at least in the "run" position to let the radio turn on. Yet it can be turned off independent of the other lights and gauges. (You do have the radio turned on right?馃Of course you do. 馃檪)
The next thing I can think of is if your charge light is on, then there may be a shorted wire grounding out what I venture to say is the power source to those items. it may not kill your battery while off because it is only getting power while in the run position.
With your shift display, are you referring to just a light is out or do you have some other non analog display?
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Thanks about the style.
You mean you were an electrical heavy line tech?
I'm not sure what you were testing to get "12v key off, .3v when running " and what your points were, but if you remember electrical theory, you would have a voltage on an open circuit, not closed. In a closed you get current, not voltage.
Also, in theory, a large wire decreases resistance and increases current capacity, and would be often desirable. That of course is in AC circuits. AC and DC have two different sets of physics.
In DC circuits, it could lead to too much current, as often a conductors resistance is calculated into circuit design to determine what size resistors are needed to reduce current to the capacity of what ever is being energized, I.e. transistors and Integrated circuits (chips) running digital odometer readouts, PRNDL displays, gauges, and the like.
A fuse is in the line to protect against a shortage, where something grounds out leading to excessive current flow and heat in the line which allows the fuse to melt, before something else does and catches fire. It would not protect against an excess of available current, which is always there, that a resistor then has to block. If they are blocking too much, then they overheat and fail (usually at the solder point first, but not always, depending on a few design factors) and that breaks the circuit open.
I don't know of any other form of step down transformer in a car that lowers voltage and limits current running between the engine bay from the battery and alternator, and the cabin area other than fusible links, and breakers. If anyone does, inform us please.
Another thing to consider, and this isn't really an electrical property issue, is using a house wire on a vehicle. Unless you used one with an outside rated sheath, house wires aren't typically designed to handle the weather that vehicle wires are.
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Aside from the new information I just gleaned from that, this also reminded me of the voltage regulator directly on the alternator.
Which I don't remember if that was checked in the previous threads.
It does have an internal regulator, just one small wire to the ECU. 40 yrs. heavy line mechanic, but electricity can flummox me, cause I hate to admit I've never really learned it. I figured justb send the worst ones to the electric shop. Same with auto transmissions. Let bthe folks that do it every day do what they do. Appreciate the info there, the next logical step is to somehow get under the damned thing anc check the lone fuse link at the starter, then put the wiring back to stock. Yes, about 3 volts running, and when I ran a jumper from the battery to the B+, 14.3 volts when running. (that was after changing the alternator.) That told me rotten connection at the starter, where bthat wire originated. -Man, if I just had my tools, jacks and stands back.....
Heavy line mechanic makes sense to me now. I originally thought you meant electrical lineman.
At this point, even if you change that wire back to a stock grade, what ever damage that has been done to cause your gauges to not be working has been done, and will still need to be pinned down.
I'm sure you already knew that, but just in case.
I think what @Sailing_Faith posted above is a good start and maybe even your finish. It fits the bill.
First鈥. There is no role for a 鈥渢ransformer鈥 anywhere in this mix (work with AC only).
And yes, I knew that馃槒 It slipped my mind and voltage regulator would have been the proper term to use, but I was forgetting it. Good to point out though and thanks!
Another thing I'm thinking is your change of your B+ wire may not have anything to do with it, as it goes form the battery directly to your starter then to ground most likely. Admittedly, I had to look up what B+ even was.. (I never heard it before) and I don't really know where your wires run. I'm not looking at a diagram here.
But in that above fix, he had no direct cause for it either.
Gremlins?
Just to help you sleep better. I know you were worried about losing your touch.
This new development arose without actually doing anything else? Just randomly tested it and found?
Do you drive this daily?
Sounds like wire insulation has worn away somewhere that it could be going through enough resistance to not blow the fuses. I can't imagine where though at the moment.
Or something is on that is not obvious.
Have you checked into what @Sailing_Faith posted?
Keep us posted. Hoping for some luck there, and will be looking. If I come up with anything...
Has to be the ECM. It's the only ytie point for everything affected, caused by too much current via larger than life gauge cable.
I'm not going to say it can't be the ECM, but I don't think it likely, at least not your original gauges not working issue. It gets readings from the various sensors that monitor what those gauges show, but I think they are on different circuits. Case in point, if the gauges aren't functioning and on the same circuit as the ECM, the engine would not be running well if at all. They may get their readings from the same sensors on a parallel circuit, but not in series with them.
It could be the cause of your new draw problem though.
Again, I think your larger than life wire probably only went to the starter then ground, so it really couldn't have affected anything. The ECM is tied in through the fuse box. The fuse box to the battery cable. By that point, voltage would be regulated by the battery, and all conductors that might have their resistance calculated as part of the total resistance would have been.
It's not likely to have even caused any kind of short because even if the insulation is not rated for outside use, (related to moisture and weather) it is still rated for 120 volt, a much higher voltage than 12, unless you had enough moisture to allow the conductor to make contact with something it shouldn't have. This could also be a cause for your draw problem.
That's about the only new thought I have for today on it, if you want to call it new.
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