A Few Misc Questions

[RonD]

Reads like 9v battery is dead, lol

Can't explain that

 

[Lefty]

About that second question... You might want to get an uprated voltage regulator for your alternator.

 

[kxri318]

Reads like 9v battery is dead, lol

Can't explain that

I'll probably just stick with the OEM relay for now. Since I replaced the cap, it stays on tight and seems good.

Anyway, I measured the voltage at every connector from the one small pin at the relay connector to the ignition switch and found that the voltage is low all the way to the switch. When measuring from the negative battery terminal to the pin on the ignition switch, I got about 11.25v at the switch and when measuring the battery directly, I got about 11.70v (with accessories on, 12v without). When I measured from the same pin at the ignition switch to the positive battery terminal, I saw anywhere from 300mV to 400mV voltage drop. It fluctuated a lot and also seemed to increase 20mV when the door buzzer was buzzing.

I measured all of the pins at the ignition switch and saw no more than 11.5v on any of the pins. A few pins had the same 11.25v and a couple had 11.5v. Side note I should probably throw the battery on a charger.

One questionable thing was two wires going to a connector under the engine bay had a bit of bare wire exposed, one of which is a fusible link. See the attachment for an image of that. Also yes I know its plastered in oil, this thing has probably had oil leaks since before I was born but I've fixed most of them. The front suspension looks brand new because of the leaks lol.

I did see that there is a diagram for the ignition switch in the tech library section so I'll check that out and measure a few more things to try and find the source of the drop sometime in the next couple days.

 

[kxri318]

I looked further into it and the drop is happening inside the ignition switch. I measured a 50mv drop from the wire that gives ignition switch its power which I'm pretty sure is normal and nothing to give a second thought, but other pins coming from the switch have about a 350mV or 0.35v drop. I can't take it off or anything because it's riveted on. I saw you can buy replacements though so I assume people just drill out the rivets.

Edit: turns out they were screws without heads, got them out with some vice grips

 

[kxri318]

So before, I said I got 11.5v at the power pins (2 yellow wires according to the wiring diagram) and then 11.25v at the wire going to the ECU relay. I swapped out the ignition switch and now I'm getting the same voltage at the power pins and the wire going to the ECU relay. The drop between those wires was eliminated but there's still a 150-200mV drop from the battery to the power pins. I can't tell where the power pins/wires are going to because they vanish under the dash in the wire loom and I can't really tell from the wiring diagram where they go. Could anyone clarify on "power distribution" or where the attached fusible link might be?

 

[RonD]

All fusible links connect to Starter Relay Post that has the Battery positive cable on it

Follow battery positive cable to one of the larger starter relay posts, with it will be several other wires, those are all fusible link ends

Often looks like this: https://www.broncozone.com/uploads/monthly_09_2008/post-889-1222112658.jpg

One post with all the 12v wires connected
Alternator, ignition switch, EEC/fuel pump power, main light switch, if it needs 12volts it is connected there in some manner

 

[kxri318]

All fusible links connect to Starter Relay Post that has the Battery positive cable on it

Follow battery positive cable to one of the larger starter relay posts, with it will be several other wires, those are all fusible link ends

Often looks like this: https://www.broncozone.com/uploads/monthly_09_2008/post-889-1222112658.jpg

One post with all the 12v wires connected
Alternator, ignition switch, EEC/fuel pump power, main light switch, if it needs 12volts it is connected there in some manner

Alright thanks. I followed that wire and found that there's no significant voltage drop until the connector that connects the wire coming from the starter relay post to the one coming from the ignition switch. I did notice something weird which was that one side of the connector seemed melted and was pretty hard to disconnect. I don't know why it melted but the metal seems pretty clean inside the connector. Not sure if maybe something else burned up along the wire to the ignition switch. It also seems to go through a few of these cylindrical things that I'm not sure what they are (They don't look like the fusible links, they literally just look like a black cylinder that the wire goes into)

 

[alwaysFlOoReD]

The melted connector probably had a loose connection, which causes heat. The heat may have been enough to start welding wires together.

Post a pic of the black thing.

 

[kxri318]

The melted connector probably had a loose connection, which causes heat. The heat may have been enough to start welding wires together.

Post a pic of the black thing.

Nevermind about the black cylinder that I was talking about, I'm pretty sure that was a different wire going through that, hard to tell when its all covered in tape. Though I'm not sure how to further test that section of the wire to find the fault since it goes inside of the big wiring loom and into the dash. I was gonna take the actual wire out of the plastic connector and look over it, but it's stuck in there. I noticed it's a little melted inside the connector too which stuck the metal connector in place and I can't move the plastic tab that releases the metal connector inside.

 

[RonD]

You can get single wire connectors with leads attached
Cut that connector out and splice in the new connector


When testing voltage or ohms on an existing wire, sewing pins can be handy
You can put the pin in at an angle so it makes contact with the wire inside the insulation and then test the wire while its "live" if its a voltage test

You can also get "needle probes" that attach to current volt meter probes for the same purpose, also quicker for testing multiple wires

Neither of these will hurt the wires insulation

 

[Josh B]

Be sure you get any chances of a short out of there, they can flare up in a hurry

I had an old Dodge Dart in the early 70s that my father and I had just put new rings and bearings in it, hadn't had it long. I was coming in through some road construction and had to stop, while I was sitting there the wiring began smoldering. Someone had put aluminum foil around the brake light fuse.
Had to re-do the whole harness and was lucky it hadn't been much worse

 

[RobbieD]

Someone had put aluminum foil around the brake light fuse.

And the real winner in that group was the guy that noticed a .22 cartridge was just the right size for replacing a blown glass fuse, and then caught some shrapnel when it cooked off.

Darwin sure was proud.

 

[kxri318]

You can get single wire connectors with leads attached
Cut that connector out and splice in the new connector


When testing voltage or ohms on an existing wire, sewing pins can be handy
You can put the pin in at an angle so it makes contact with the wire inside the insulation and then test the wire while its "live" if its a voltage test

You can also get "needle probes" that attach to current volt meter probes for the same purpose, also quicker for testing multiple wires

Neither of these will hurt the wires insulation

I found a 12 gauge weatherpack 1 pin connector so I just bought that and put it in. Seemed to bring it down from a 150-200mV drop to a little over 100mV now. I tested it and got about 100mV drop and then about 200mV drop when the door buzzer was buzzing. I should mention that this is over the entire circuit. When I tested the positive drop specifically, I got 22mV drop key off at the ignition switch, then 23.5mV key off with the door buzzer buzzing. After that I tested with the ignition set to run and got 142mV drop and then 162mV when the door buzzer was buzzing. The ground side had no issues as it barely broke 8mV drop with the key in the run position. I also measured right before the connector in the engine bay with a sewing needle and saw 113mV drop with the key in the run position. It seems like the voltage is dropping over the entire wire. I got 100mV of drop at wire on the driver side of the radiator and then 60mV of drop on the passenger side. There's no clear point where its a normal amount of drop and then a large amount.

 

[kxri318]

I did another test where I disconnected the original wire that goes to the switch and ran a brand new wire straight from the positive battery terminal to the ignition switch and I still see pretty much the same drop when I turn the key to the run position. Measuring when started shows about 1.1v drop at first and then slowly drops to 0.4v drop when warm.