More Alternator Trouble Shooting (3 Viewers)

[GoatWorthy]

Full re-cap:

For the past 2 years my cruiser has had some parasitic drag on the battery. If she wasn't started and run about every 5-7 days then the battery would be dead and require a jump. Fast forward to now and the alternator is not supplying power when running.

I took the alternator to a local rebuild shop and had it gone through. Now they didn't rewind the alternator, but they bench tested it and said it was solid. I installed the new alternator, but the battery died after multiple starts over 2 days and approximately 20 miles put on.

I went ahead and ordered a new alternator which just came in and plan to install it this weekend and see if the problem duplicates. If it does duplicate then I am assuming power is not getting from my alternator to the battery and/or engine - wiring problem.

I've looked online for wiring bundles, but can't seem to find them. Any recommendations on wiring bundles or which one to begin with etc...??

Thoughts??

I'm not electrically switched on - get it? ha... but wanted to attempt locating the problem and fixing myself if it's an easy one before sending to a shop to chase wires for me and take who knows how long.

Thanks!

 

[duncanrm]

I'm not electrically switched on - get it? ha... but wanted to attempt locating the problem and fixing myself if it's an easy one before sending to a shop to chase wires for me and take who knows how long.

Its really worth learning a few basic diagnostic tests if you own an old vehicle.. when time permits hit the Youtube and learn how to use a voltmeter, understand the value of a test lamp, and dig into the basics of an alternator.

Put your new alternator in, and measure the battery voltage with the engine running.. if the battery is deeply discharged it might only show 13V but it should slowly start to come up and when full charged and with the engine running you really want to see it up towards 14V. This will confirm alternator operation.

No wiring bundles required - its easier to do a simple repair on a factory loom than replace it. Also double check that if your existing wiring harness is setup for an externally regulated alternator that you're putting that sort of alternator in. Most replacement alternators are now internally regulated (green plug) and its common to see dodgy conversions of wiring from external to internal.

Learn how to do a parastic current draw test too - you can explore your underlying fault after you've confirmed correct alternator operation.

 

[GoatWorthy]

Thanks for the write up.

Attempted the voltmeter test but the engine died prior so that's the first diagnostic I'll run with the new alternator and fully charged battery.

Good info on internal vs. external. I didn't realize that was a thing so I will look at it first thing in the morning. The new alternator actually has a black plug that is a pigtail - what I mean by that is it has a 4" dongle coming out with a female end. The original alternator just has the wire bundle plugging directly into it without this dongle. I'll post pictures if that isn't clear.

If the battery isn't showing around 14V then I'll start chasing wires to see if I can figure out what the problem is.

Thanks again.

 

[toy_tek]

Don't forget to check, remove & clean all your grounds. Especially the one that comes off the battery.

 

[Seth S]

When you first turn the key on and all the dash lights come on does the charge light turn on? This is before your turn to start position

 

[duncanrm]

Good info on internal vs. external. I didn't realize that was a thing so I will look at it first thing in the morning. The new alternator actually has a black plug that is a pigtail - what I mean by that is it has a 4" dongle coming out with a female end. The original alternator just has the wire bundle plugging directly into it without this dongle. I'll post pictures if that isn't clear.

Black plug does generally indicate externally regulated.

Your description of how the old alternator was wired is cause for concern.. send photos. Also send a few general photos of the engine bay

 

[GoatWorthy]

Ok thanks... I'll dig into grounding wires and location to check them out.

Headed out to get a new belt - figured I might as well swap them while I have everything off. I'll some pics later this afternoon regarding the alternator connection.

I'll have to check regarding the charge light. Not sure I ever noticed that. With the charged battery I'll check that out. Thanks for that.

 

[GoatWorthy]

Now that I’m looking at it all it does seem that I have a lot of electrical stuff going on. Nothing to compare to as I’ve never seen under another FJs hood, but snapped these photos. Maybe it’s normal but it appears to have numerous pigtails and add ons etc…

One of the alternator and then pos and neg on the battery.

I noticed wires running directly from the alternator to headlights and running lights… numerous connectors that weren’t connected to anything etc… can take more pics if these seem like there more be going on.

Wondering if it had electrical problems and someone simply bypassed things vs fixing if that makes sense.

 

[GoatWorthy]

replaced the alternator and tested with the multimeter…. 12.49V when not running and 12.46V while running. So I guess my problem isn’t the alternator. Going to swap the rebuilt OEM one back in and take her in to chase wires unless any of y’all can give me some baseline stuff to check.

Going to YouTube how to check grounds for starters. Not sure how to know if that’s the problem or not.

Is it just the one ground from the pos battery terminal to the engine block/frame? That’s the only one I see.

Thanks for the input

 

[DrRock]

You might have a poor connection between your alternator output and the fusible link, thus the low reading. Where did you probe when you did your test?

Cheers, James

 

[GoatWorthy]

You might have a poor connection between your alternator output and the fusible link, thus the low reading. Where did you probe when you did your test?

Cheers, James

I simply placed the probes on the battery pos and neg terminals.

By fusible link do you mean the actual fuze in the dash?

Thanks

 

[TheElegantFox]

I'm not an electrical wizard, but I traced a myriad of ghost electrical issues to a loose and corroded positive battery terminal connector. Those points are most sensitive than you'd think and I needed to clean the exposed copper and re-tighten the clamps to solve my battery charging issue. I sprayed some Napa terminal protector on it afterwards to seal it.

 

[duncanrm]

My step 1... based on your fault finding so far, would be test continuity between the Alternator Output (the big fat cable on it) and Battery Positive.. if that's intact, I'd move to verifying the alternator is actually being "excited"..

There's a few sins in your engine bay, running loads off the alternator output is inappropriate. I cant tell if there's a voltage regulator still in place in your engine bay (wider photo)?... I'm really leaning towards a basic alternator wiring fault and the only way to resolve that is with a basic working knowledge of alternators and more information on the current state of the wiring loom setup (internal vs external), some insight into the 60 series charge relay and a bit of technical curiosity that leads you to learn more along the way.

 

[DrRock]

I concur with @duncanrm above, you have some crimes from a PO so my steps would be as follows:

1. Make a temporary jumper wire from 10 gauge wire to go from the + terminal on the Alt to the + terminal on the battery. Start the truck and see if you have better output to the battery. It should be ~13VDC at idle.
2. If the above yields good results, then one can infer that the fusible link has worn connections and needs to be replaced/rebuilt. The fusible link is just off the positive side of the battery terminal. If you do a search here, there are many threads with photos etc to provide guidance.
3. If this is not the issue, then I’d move on to diagnosing the alternator.
4. I’d definitely update your ground cable and connection to the battery. These can easily be sourced and fabricated which is always a good idea as aging wires do not perform as well as new ones.
5. Lastly, if you do have a fusible link issue, @CruiserTrash makes a great kit to replace the stock unit which is NLA. His unit has a nice fuse too which can be sourced anywhere, making replacement much easier.

I also have a rebuilt alternator which i sourced from my local alternator shop, the quality is much better than what one would get at your local auto parts store too so my suggestion would be to find one in your area and see if they can rebuild yours or order the one I have, part number is visible in the picture below.

Good luck and let us know how it goes.

Here’s what my connections from the battery look like now after updating to the CruiserTrash fusible link replacement, new battery terminals and ground cables and overall cleanup of the wiring: