electrical gremlins are back

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evans68cuda

evans68cuda

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Since my previous thread, No Power in the car, but there is in the engine bay ,I got power in the car and all was good. The car would start, had all lights (except the DS brake light and hazards but that's a different issue) wipers worked, everything. That was Sunday and I didn't touch the car all week while I've been at school and work until today when I decided I would go put it my new flasher yo try and get the hazards to work. And there was nothing!!!! I have 12v at the battery, the starter relay, and the alternator. I put my positive lead on at the ignition wire at the bulkhead and again 12v. I have a voltmeter inside the car and when I open the door, it moves the gauge to 10v, so I know there is power at the door switches. Then when I turn the key to "on" it reads 12v!!!! I've looked at factory diagrams over and over and even the simplified one that shows the igntioon wire through the bulkhead to the ammeter and then ignition switch, headlight switch, and fuse box and so fourth. Any suggestions would be awesome because I've been at this for hours and really need to do my homework now.
 
If the dome lamp alone pulls down to 10V start at battery and its connections.
A volt gauge shouldn't be live to show anything unless ign' switch is on but you did state "voltmeter" so I don't know whats what exactly.
 
Sure sounds like the bulkhead conection is bad. Did you unplug it and check it? It will show signs of damage

The best thing you can use to check voltages is a Power Probe. Not a voltmeter or a test light. These days its a must have in your tool box.
 
It's either in the main power path from the battery onward inside the passenger compartment, or it's a grounding issue in your voltmeter circuit

YOU PROBABLY HAVE more than one problem

DO YOU HAVE a factory service manual?

Pleas do not start more threads on this. All that does is make things harder to follow
 
I checked the connections last weekend and all looked good, I'll try again. And ok I'll look into getting a power probe today. The volt gauge reads 10v when I open the doors with the key off, and then 12 with the key on. And sorry 67dart273, I just didn't know whether people would see my update. And I have the wiring diagrams online that I've been looking at so much I almost feel like I've memorized them. I was reading the MAD article and am strongly considering doing that tonight. Should I do this MAD upgrade first and try and solve the problem?
 
Started doing the MAD bypass and decided to go with 8awg wire and a 12awg fusible link, anyone against that? Other than that we'll see what happens!
 
Frankly I think you should have found the problem first. Introducing new problems with an (accidently improperly done) modification is no fun.

The main fail points in these cars in no particular order are:

Poor connections in the bulkhead connector
Poor connections at or IN the ammeter
Poor connections or failing ignition switch and connector
Poor connections in the fuse panel
In rare cases the welded splice (see MAD) this is a factory splice a few inches away from the ammeter in the black wire, up under the dash
sometimes the fuse link corrodes inside the insulation, causing problems, and intermittent connections.
 
I pulled the the bulkhead off, there was no melting issues, but the wires are old and worn so I thought using the new wire in the MAD bypass would be a smart idea. I have a question though. So i pulled the old wire going to the alternator out and the wire from the starter relay to the welded splice. How exactly do I put these wires together? In the MAD article, it shows them coming together with taped wrapped around it into the fusible link. Just need clarification on how to splice these together. Also a 16awg fusible link seems kinda small for this doesnt it??
 
68cuder said:
I pulled the the bulkhead off, there was no melting issues, but the wires are old and worn so I thought using the new wire in the MAD bypass would be a smart idea. I have a question though. So i pulled the old wire going to the alternator out and the wire from the starter relay to the welded splice. How exactly do I put these wires together? In the MAD article, it shows them coming together with taped wrapped around it into the fusible link. Just need clarification on how to splice these together. Also a 16awg fusible link seems kinda small for this doesnt it??
Click to expand...
I am not as electrical savy as most of these guys, but when I stared my 7 yr build, the first thing I did was start a complete re wire. I didn`t want 49 yr old wiring on anything !
 
68cuder said:
........... i pulled the old wire going to the alternator out and the wire from the starter relay to the welded splice. ........ Also a 16awg fusible link seems kinda small for this doesnt it??
Click to expand...

You have me confused because there is no wire from the welded splice to the starter relay. There IS one (black) from the splice to the alternator

So far as connecting them there are various sized butt connectors, but if you can solder, that is likely best. I HAVE STOPPED using plastic butt connectors, and instead use BARE ones which I can crimp and or solder and then heat shrink. Sometimes with several wires, some of which are large gauge, making two splices is easier and more manageable.

So far as the fuse link size, even a fuse can be viewed "as a short undersized wire." A fuse is something in a circuit which is "easier to melt" than surrounding wire/ devices. The fact that it's undersized BUT IS VERY SHORT means that there is very little voltage drop under normal conditions.
 
Here's a picture from MAD of diagram 2. I circled the part that I'm not sure how to do exactly. The old black wire that came out of the bulkhead to alternator. Can I run it straight to the starter relay with a fuse it does it need to be spliced with the red wire? And what gauge wire?

IMG_9174.PNG
 
Size of fuse is "up for speculation." The reason you are doing this is to PARALLEL the old black and the old red which now, instead of conducting charge current on the road to the battery, simply power "stuff" in the interior of the car. So the current requirements on the "new" wiring is now very much lowered, and of course the object is to protect the bulkhead connector

(On a side note you can get the new bulkhead connector terminals they are known as "Packard 56) terminals. Make sure you get the proper ones)

The one big thing you are trying to protect (with a main fuse) is the size of the wire and the terminals through which they go

Other factors is WHERE you mount the fuse(s)/ breaker(s). If you mount them in the engine bay, subject to high engine heat this DERATES the fuse/ breaker amperage
 
After the MAD bypass has been completed, still the same problem! I really dont know what to do now. I have the wires coming straight through the bulkhead to the red and black wires so I can knock out the bulkhead as being the issue, but like I had been saying, it really did not look bad before. I am going to check the welded splice next since i do not know what else to check.
 
Welded Splice looks good.... my multimeter is only reading .2v with the key on though!!! What's going on?! really lost right now. Any other ideas???
 
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68cuder said:
Welded Splice looks good.... really lost right now. Any other ideas???
Click to expand...

You are going to have to start being absolutely specific

"What" doesn't work?

"What" are the problems?

"What" is the voltage readings that might be wrong. You must post specific wiring/ connection/ termination points, referenced to the FACTORY diagram.

"Let's say" the headlights don't work. I/we would ask "both high low beams?" And would probably tell you to pull out the dimmer switch and take measurements down there "to start." Just an example
 
I have my voltmeter connected to the voltage regulator (I have a grommet for all my aftermarket gauges that go through the firewall so I tested and found that was a switched 12v source) so I have full 12v at the starter relay, voltage regulator, and alternator. When I open the car door, the voltmeter reads 10v and drops down to nothing once I close it. Inside the cab there is nothing. No lights, radio, heater blower or anything at all. When I turn the key, my voltmeter reads 12v however. What is weird, when I use my multimeter to find where I have power in the car, I only get .2v at the welded splice. But I was getting 12v at the splice of the black and red wires that are spliced into the fusible link that go to the starter relay. I think I covered almost everything. I am at a total loss right now. Oh and yes I can jump the starter relay to start the motor.
 
Alright you need to start over and be incredibly specific

VOLTMETER.....What is this and how do you know it's accurate? Is this a dash mount gauge? What I'm wanting you to do is take some measurements with a DECENT accurate meter

The meter is hooked to the VR? You mean the VR IGN terminal?
You need to CONFIRM THAT by hooking a digi meter from BATTERY NEG to the VR IGN, does it actually show 10V?

NOW.........

"When I open the car door, the voltmeter reads 10v and drops down to nothing once I close it. Inside the cab there is nothing. No lights, radio, heater blower or anything at all."

You need to take some measurements WHEN THIS HAPPENS to find out where you are losing the voltage. Turn on the headlight switch, Maybe the key to "accessory" and the radio

Now start "wiggle testing" connectors, and start with the bulkhead connector. If that does not turn up anything, trace your (now modified) path from the battery through the bulkhead........Probe the two bulkhead terminals now feeding main power into the interior. You have voltage there at either/ both of those two?

Now go inside the car and probe the same two terminals, you have voltage THERE?

"All this time" you are taking measurements be aware if anything comes to life, the headlights, radio, etc.

I hope this gives you some hope: This / these problems CAN NOT be very complicated. There simply is not that much "stuff" between the battery and what isn't working

Also.............."what did you do" with the bulkhead connector terminals, to clean them replace them, etc?

YOUR TEST MULTIMETER is your friend. If you don't have a decent one, BUY one. ANY auto parts store, Home Depot, Lowe's Sears any hardware store sells decent meters. This is a CHANGE from when I "was a kid." In the 60's and 70's You could not just go anywhere and buy a decent multimeter.
 
It's too bad I cannot "be there." I'm not bragging..........I could teach you more in 15 minutes "there" than I can in days of haphazard internet time
 
The voltmeter I am referring to is mounted under my ashtray along with an oil pressure gauge and a water temp gauge. They are I equus brand. When I disconnect the battery, the gauge reads just below the "8" on the meter. When I connect it with the key off, it reads right at 8 so I know something is wrong there. I plan on connecting the voltmeter to the fusebox once I get all of this solved. So currently the positive voltmeter wires is routed through a grommet in the firewall to the bottom post on the voltage regulator. I have 12v there when the key is on when I test that with my multimeter. I tried wiggle testing at the ignition switch, headlight switch, fusebox, and bulkhead and nothing. I'll keep trying that tomorrow. After I soldered the black and red wires from in the cab, out through the bulkhead and to the fusible link, I used my multimeter there and tested 12v. I then heat shrunk it so I can go back and test again, because I'm wondering if it's possibly a bad solder? I'm using butt connectors to connect the 2 big red and black wires at the bulkhead and when slipping my multimeter in there, I get .2v. I'll go back and take the butt connector off for a more accurate answer however. As far as the bulkhead connectors, nothing was melted or heavy corrosion so I wire brushed the terminals and sprayed them with compressed air. I cut back some of the factory tape around the wiring to get to the welded splice which when I put my multimeter on there, I got .2v also!!! I know this isn't rocket science and this is driving me crazy not figuring it out!
 
one of my buddies has that power probe so I am going to ask if I can borrow it. But as of now, I get 5v at the red and black 10 gauge wires at the splice in the cab with the key OFF. when I turn the key ON, it drops to .1v. And when I either open the door, or pull out the headlight switch, the voltmeter reads 10v.
 
More info: when the key is OFF, I get 5v at the fuse box "hot buss" red w/ white stripe wire and at the welded splice. When i turn the key to ON, I get .1v at the same spots, and then .4v when the key is in ACC. Also, my temperature gauge immediately goes to H on the gauge when the key is on or off, it has always done this and is nothing new but I am trying to give as much info as possible.
 
Update: just grounded my block to the blower motor and everything works! Not sure if this is the fix however. Weird that everything worked for a long time and all of a sudden stopped.
 
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