Electrical help! Sudden loss of voltage to everything. (1 Viewer)

[Bluegrass40]

Hi everyone

Here is what I'm dealing with:

-'78
-Stock starter and ignition switch
-fully charged battery
-electric fuel pump

I had just finished scrubbing and spraying down the inside of my hard top (removing adhesive) and washing down the inside of the truck with a hose while I had all of the seats out. I finished up and was moving my 40 from the driveway to the street (on a side noted, Truck has maybe 100 miles on it in the last 12 mo). When I want to start the 40, I turned the key to acc and the fuel pump turned on and normal. I turned to crank and got nothing at all from the starter. This is not abnormal. I have been assuming that it was the starter solinoid going bad. I turned the key 3-4 more times before The truck started. I pulled into the street and then put it in reverse to reposition. The truck stalled (likely because I was sitting on a stool since the seats were out). I went to start it back up and got nothing when I turned the key. Not even the fuel pump. Nothing. I tried the turn signals, brakes, headlights and got nothing. There was the smallest of twitches (almost unnoticeable) on the amp meter. I checked the battery cables and they were tight. I grabbed a meter and checked the battery voltage and it was 12.25v.
I checked all of the fuses and they were all fine.

I then checked the harness coming from the column and noticed that the green connector had a black spot on the side. I smelled it and it didn't smell like burnt plastic or electrical so I think it is unrelated to this event.

I thought that I may have gotten something wet that did not like being wet?? I'm letting it all dry.

The most confusing part is that the lights don't work?!

What else should I do to root cause the issue?

Possibly an ignition switch issue (would not explain lack of brake and head lights)?

Thoughts?

 

[spotcruiser]

Check your fusible link at the battery.

 

[Bluegrass40]

Wow. Sometimes the simplest things slip my mind! I'll give it a check and report back.

 

[Bluegrass40]

Fuse at battery checked fine.

 

[spotcruiser]

Stock would be a fusible link. Is it possible you have a fuse in addition to a fusible link? That white/blue (WL) wire shown burned at the column connector is power to your ignition switch. All of the fuses in your fuse block are downstream of the ignition switch.

Something else to consider is the ammeter. The ammeter is in series between the battery and that white/blue wire to your alternator and ignition switch. The ammeter can also function, unfortunately, as a fusible link.

 

[Solace in Solitude]

I'd check that green connector a little closer... As spot said, the white-blue carries power to the fuse box... Also to the ammeter... And everything else... The inside of that connector looks to be burnt as well.

Unwrap the black tape and see what it's hiding... Make sure water hasn't caused a short... Water conducts...

 

[gator25]

I'd check that green connector a little closer... As spot said, the white-blue carries power to the fuse box... Also to the ammeter... And everything else... The inside of that connector looks to be burnt as well.
@pngunme probably hit the nail on the head, that white and blue is the power wire. I'd trace starting from the battery.
Unwrap the black tape and see what it's hiding... Make sure water hasn't caused a short... Water conducts...

 

[Bluegrass40]

Great info guys. Thx.

I could not find a fusible link I think it may have been replaced with a 15amp inline fuse.

Looks like I am going to be digging deeper into the harness.. I knew it was only a matter of time:/

 

[Solace in Solitude]

... And you're sure that 15amp fuse is good?

Here's a fusible link on my '78... Between the battery+ and the harness .. The black wire between the two white connectors.

Were you hosing down the cab or the engine compartment or both?

 

[Bluegrass40]

... And you're sure that 15amp fuse is good?

Here's a fusible link on my '78... Between the battery+ and the harness .. The black wire between the two white connectors.

View attachment 1327170

Were you hosing down the cab or the engine compartment or both?

I visually inspected the 15amp inline fuse and it looked good. I also puke a meter on it and it was continuous.

I do not see a dfusible link under the hood. I'll post a pic later. Making burgers for the fam now

I was cleaning the inside of the cab only. If anything there was just overspray or water that drops onto the column/ wiring. There was no direct spraying.

I guess the stall could have been due to an electrical problem and not poor driving from a bathroom stool?

I appreciate everyone's input.

 

[Bluegrass40]

Upon second look, the fuse was not in place of a fusible link but rather a fuse for the Omni magnum ignition.

Let me know if these pics are a help.

 

[emac]

Check power on the white wire going from battery to the fender. What is the connector that the white wire goes to prior to going to solenoid? Is that some kind of fuse/breaker.

 

[Solace in Solitude]

You've got so e connections that really need to be cleaned up... Especially the battery+ and connections downstream from the battery+.

What is that cylinder on its side with the large terminals? A battery isolator or something?

The thing @emac referred to is rusty as well.

I'd clean all of those and slather vasoline or something on there.

The short pink wire, between the two yellow connectors looks like it could be a homemade fusible link... What does it say in that wire?

Also, there is a short (1/2") length of what looks like white wire, coming off the harness, in the pink wire loop... Where does it go?

 

[Solace in Solitude]

Some of those yellow connectors... Like the one emac referred to... Look suspect... When you clean them, see if they are tight?

 

[Bluegrass40]

Here are some more details. I checked for voltage at several locations. Bottom line. I'm getting 12v at the ignition switch input but only ~1.5v at the at the output which should be running the electric fuel pump. I checked voltage at the fuel pump and it was slightly lower (likely just due to wire and connector resistance).

At one point when I was probing the ignition terminals, the fuel pump started pumping (I believe voltage jumped to around 12v on the output of the ignition terminals that drives the fuel pump. I turned the key and there was a click (starter did not fire) and then the voltage dropped back to ~1.5v and the fuel pump dropped back out.

Odd.

 

[Solace in Solitude]

I'm not familiar with Omni Magnum Ignition, or how it effects your ignition switch...

Is it possible the 'burned' signs on the green keyswitch connector indicates you may have burned the ignition switch up?

Did you remove the tape below that 'burned' green connector and see what the wiring looks like?

Maybe your measured 12.xVolt ignition-input dropped when you measured 2.xVolts at ignition-output... e.g. maybe the 12.xVolts input is only momentary...

Can you start the truck by hot-wiring it?

 

[emac]

Does jiggling the key when starting make any difference? I wonder if the ignition switch is shot. They aren't real expensive, but I hate throwing parts at a problem until I am sure it is bad. Maybe the wsm has some testing procedures for the switch.

 

[bj40green]

Here is your problem. The WL (White / Light Blue) wire is the main power line between the IGN switch, Alternator and Ammeter.

Replace the connector or ask @Coolerman for an replacement.

Rudi

 

[Bluegrass40]

Hi everyone. I resolved the root cause for the power loss (and found several updates that I want to make along the way).

It ended up being a high resistance connection between the positive cable and battery terminal. The cable was tightly connected to the terminal at the battery but must have some corrosion between the clamp and terminal.

For those that are interested, here is how I found it:

1. I connected a wire to the positive battery clamp (which was tightly connected to the battery terminal) and then connected the other end to the terminal on the ignition switch that would power my fuel pump. I got nothing. I double checked the voltage and it was 12v. This pointed to a high resistance issue in the circuit.
2. I then connected a wire between the battery clamp directly to the fuel pump. The pump did not turn on. That confirmed the high resistance condition..
3. I then connected a wire to the negative clamp that was on the battery terminal and tapped the clamp on the positive terminal. There were no sparks etc. Then I tapped the wire on the positive post and there was a small spark. Bingo!
4. Then (because I didnt have the tools handy to remove, clean and reattach positive clamp) I connected my wire between the positive clamp and the positive termianal. I got in the truck, turned the key and it fired right up!

I'll clean the posts/clamps tonight. I'll be fixing with wiring nest that I had the pleasure of fumbling through in the near future.

 

[Solace in Solitude]

Glad you figured it out!!

That's the first thing I mentioned in post# 13... I always make sure the connections are clean and tight and are slathered in vasoline or dielectric grease... Or something, to keep the corrosion down.