84 F350 - 460 Auto

I want to add that this thread was originally created to diagnose my ground wires in relation to pulsing of my lights and ammeter. However, the actual topic of the pulsing isn't introduced until post #36.

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UPDATE (2/17/2020): Pulsing solved. Post #196

UPDATE (2/8/2020): See post #137 (Page 10) for a bunch of voltage readings under different circumstances.

UPDATE 3: See post #106

UPDATE 2: See post #71

UPDATE: New 2 gauge battery cables. Negative straight to block, new 4 gauge ground from block to frame, new 10 gauge ground from block to firewall, added 10 gauge ground to fender from negative battery post, and wired a ground from the alternator to regulator.

Also I might have found a new symptom. Been using my headlights and heat more with cooler darker mornings. I’ve noticed my turn signals slow down in idling after maybe 10 min of driving. The other day they even stopped working altogether. Really felt like it was related to the pulsing of my charging system.

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Was doing some preliminary research and looking around at my grounds for doing a voltage drop test and I'm trying to figure out if my grounds are even correct.

1. On my negative battery post the big clamp with 4 gauge wire goes to what looks like the old bracket for the smog pump. (Seen in pic below with red circle)

2. There is another connector on my negative battery post that's also 4 gauge that looks to run to my engine block. It's tucked under the #1 plug and really hard to get to. I can feel it but i can't really see it. Not far from where it connects to the block there is a metal "flag" hanging near the back of the alternator that isn't connected to anything. (Wire seen with yellow circle in pic below).

3. The solenoid has a 4 gauge wire running down to the starter.

4. The alternator has a small ground wire (maybe 12-14 gauge) that goes to a harness into the voltage regulator.

Lastly, I have no idea if I have a ground for body to frame. If i should have one where do i look for that?

 

Hey Coach. Is that the main battery (NEG) cable terminating at a bracket bolt?

I don't know if that's the as from factory OEM ground location but it isn't a very good spot particularly. Right at a bracket on the alternator is seen sometimes. That might have been OK when everything was new. The bolts and brackets start to corrode though. I like to chase the threads out and wire brush the bolt directly to an unused boss or pad on the block, near the starter say, easily the highest current draw. Clean and bright down to bare clean metal. The main ground connection point has to be as good as you can make it, it's not gonna improve any downstream. Coat with vaseline or NO-Ox to keep corrosion from returning. Make sure the grounds are tight. Physically tight isn't necessarily electrically tight.

If the cables are original or old they should be replaced. The voltage drop test will show they are defective if more than say 20 or 30 years old I expect. Don't buy the el-cheapo cables, the blister-pac generic cables at the auto parts stores. Good quality, heavy AWG pure copper cables are sold at tractor supply stores and welding shops, places like that. They don't cost that much more. Cheap cables have schiffy crimps or solder, and the terminals deform so easily they never tighten properly on the battery posts again. Look for more cables from the frame to the engine block or block to firewall. Anywhere you see a cable or wire bolted to the body or frame or metal portion, that's a ground strap. They are all important or they wouldn't be there.

 

Yep... main negative cable going to old smog pump bracket. Came to me that way. I'm confused now though b/c the other 4 gauge wire on the negative post does seem to run to the block, but the "flag" is just hanging there. Wondering if that flag is for the frame.

 

You are confused think of us when you say another "4 gauge wire on the negative post"?
Can you take a picture of the battery post, you did not get it in that picture so we know what you are talking about.
Dave ----

 

Here’s a look at the cable going to engine block and the “flag” connected to nothing.


This is a look from under of the cable to engine. Wasn’t able to get a good look at this yesterday but I see now it’s under a bracket for trans cooler lines and bracket holding cable to starter. Obviously this looks like poop!

 

Those cables are all bad. They were probably defective 20 years ago. Get some nice 2ga or better pure copper from a truck shop or tractor supply. They will have service grade terminals and somebody who knows how to crimp them and has the right tools. Bring the old ones with you and they can match everything up.

 

Ok, question now is do I even need the one going to the bracket? Or can I delete that one and just have the one going to the block? Should that flag be attached to the frame? Or should I run another cable from the block to the frame?

I couldnt find a ground from block to frame. Unless I was looking in the wrong spots.

 

Yes the flag was the frame ground.

 

Yeah that flag is supposed to go to the frame. It takes the place of two cables. Since it isn't hooked up it might even be the cause of the power fluctuations. It's important to have the grounds hooked up and in good condition. The idea is that the engine, frame, and body/firewall are all at the same ground potential.

The starter probably draws 150 amps, that is enough to weld with. If the starter can't get the current from the ground cable it will search for a ground and take the long way home through something not designed to carry any juice much less 150 amps. I've heard stories of throttle cables and brake lines glowing red hot, roasted radiator innards, stuff like that. Good catch! You'll get 'er straightened out. Don't delay though.

 

Gotcha. So that means I can delete the cable going to the old smog bracket and replace the other going to block with new flag on frame?

 

Well I'd be inclined to see if I could find exactly what the factory setup was for an 84 F350 and maybe do that, or maybe not. The way I prefer is a heavy cable that terminates directly to the block by the starter, and and a heavy cable from the block to frame, and heavy cable from block to firewall. Sometimes people will terminate the negative battery cable to a bolt on the starter, and from there to the frame. That seems to work OK too. I run a cable from a bolt on the starter to the frame.

Did you ever get a voltage drop test for headlights? Set the meter on its lowest setting. Turn the lights on. One probe on the (-) negative battery post itself, and the other on the negative terminal of the headlight itself. Can pull back the socket partially or slip a wire in there. I bet it's more than 0.1 volts.

 

Thinking I'll do new clamps with 2 gauge. Negative going to the block and then another cable from block to frame. That would leave me with only 1 cable on the negative post. Was thinking I'd use the same spot/bolt to run the block to frame cable as the battery to block?

 

Just to be clear, when you talk about "clamps" don't use those emergency battery terminals that bolt on. Those are OK for emergencies to get home on or something like that but they are no bueno for permanent use.

 

Do you mind giving me an example of what kind I should get? Sorry for confusion.

 

I would get new cables, quality cables are just as much about the terminals as the cable itself. They are usually high quality solid copper terminals that have a zinc or tin wash, they aren't made of lead usually, and crimped VERY solid. A tractor supply or a welding shop can usually make them for you in any length you want. I bought a set of 00 cables for my slick from a Fleabay seller. A little overkill but they aren't undersized! Just select gauge, length, and ring terminal size. I'm not advertising for these guys, just trying to show kind of what you want and how to make that happen. A 2 foot 2 ga. cable is about $16 delivered, more $ than the cheap cables, but they will last.

Gauge Wire and Cable