FJ80 Battery mystery, won't start nor stay running. (2 Viewers)

[Pskhaat]

My FJ80 (3FE) won't start, needs a jump every time, won't stay running at low RPMs. AND THE BATTERY checks out.

1. My 80 will not start without a jump. Dash lights don't come on. Thought it was (naturally) the battery. Right?
2. Nope, battery checks out brilliantly. Is does not discharge much if at all during long drivers. Not a spot of corrosion or other problems at terminals. I have always had extra grounding wires from - terminal to body+frame. Microprocessor controlled charging and test of the battery out of the vehicle yields a perfectly-working 84-month Toyota group 27. Even Toyota Stealership says battery checks out fine.
   
   
   
   
3. 80 jump starts totally OK, and runs once started, albeit at lower RPMs than expected, and I need to keep the RPMs up get the alternator pumping some juice. I always jump to the terminals. But now can't put too much load on the electrical. If I turn on highbeams, or roll down a window the car dies, and needs a new jump. Cold outside and come to a stop? Another jump needed.
4. The voltmeter shows normal. I have a small analog multimeter but I'll infer from the needle around 13.X volts. Should it be 13.8+VDC maybe, but this is ALL within nominal range.
5. Goto #1. I STILL have to jump start every bloody time.

This does not make sense:

• If it was the alternator then voltage would be quite off or relying on battery for sufficient amperage and discharging. But battery is testing fully charged all the time.
• If it was (again) the battery, then it wouldn't test as it does nor hold a charge, but it does.
• If it was the fusable link or the battery terminal problems then why does a jump start work just fine?
• No matter how long I drive the battery neither charges nor discharges, but it won't start with battery unless jumped.

The FJ80 with port-side battery requires a Group 27. Not the F, so I only have this one battery, but hell, it seems to be working quite well everywhere.

 

[jonheld]

First thing is to verify that all 3 fusible links are intact. You must use a meter for this.

 

[Pskhaat]

First thing is to verify that all 3 fusible links are intact. You must use a meter for this.

Why would a jump on the battery terminals work prefectly well with faulty fusible links?

 

[Outsane]

Check for loose grounds?

 

[mudplacement]

+1 for grounds
Generally I check terminal corrosion, fusible link and then grounds.

 

[TurbodreamZ]

Every time? What if it’s been driven for 30
minutes and you turn it off but turn it back on immediately?

Does your battery light stay on?

Alternator might be going out if you’re only getting 13V. When running and charging mine is at 14.xV. A healthy charging system will maintain 14.7v

 

[CJF]

Why would a jump on the battery terminals work prefectly well with faulty fusible links?

Stop overthinking things and start checking things. If nothing else, put a multimeter across the terminals, check the voltage while running and not running, and report back.

 

[Pskhaat]

Stop overthinking things and start checking things. If nothing else, put a multimeter across the terminals, check the voltage while running and not running, and report back.

Zero ohms resistance across both fusible links. 12.3ish volts at rest and 13.5VDC once running. The tiniest of all sparks when reattaching to terminals. No corrosion. Ground cables sound and firm.

I'm open to further testing and continuity/resistance tests that could be recommend. Thus trying to determine with lgoc what else this can be.

 

[mudplacement]

Zero ohms resistance across both fusible links. 12.3ish volts at rest and 13.5VDC once running. The tiniest of all sparks when reattaching to terminals. No corrosion.

I'm open to further testing and continuity/resistance tests that could be recommend. Thus trying to determine with lgoc what else this can be.

Check all your grounds, make sure they are tight and free of corrosion.
Ive seen a 1fzfe behave the same way before due to bunk grounds.

 

[ChaseTruck]

Why would a jump on the battery terminals work prefectly well with faulty fusible links?

The extra juice from the jump overcoming resistance?

Didn't we have a thread recently where electrical shenanigans were related to the ground cable to the block being loose, not at the battery, but at the engine block?

I'm reading this with interest since our '93 has developed an appetite for jumps over the last year, despite a supposedly good battery. I haven't had time or desire to dig into this, so reading on MUD it is for now...

 

[tmxmotorsports]

Zero ohms resistance across both fusible links. 12.3ish volts at rest and 13.5VDC once running. The tiniest of all sparks when reattaching to terminals. No corrosion. Ground cables sound and firm.

I'm open to further testing and continuity/resistance tests that could be recommend. Thus trying to determine with lgoc what else this can be.

13.5 should be around 14.5

 

[jonheld]

Zero ohms resistance across both fusible links.

There are 3 fusible links.

 

[Pskhaat]

Every time? What if it’s been driven for 30

Even driving for several hours on end.

Does your battery light stay on?

Battery light does not stay on.

Alternator might be going out if you’re only getting 13V. When running and charging mine is at 14.xV. A healthy charging system will maintain 14.7v

This may be, but this is a problem before even the alternator takes its first rotation :-(

 

[Pskhaat]

13.5 should be around 14.5

Agreed and that may be my next issue to address, but it won't even start. This is a problem way before the alternator even takes a spin.

 

[CJF]

You do you, but I would 100% swap in a different battery.

 

[Pskhaat]

Here are my steps with some video, maybe someone could help diagnose?

Step 1. Establish good battery. Which I have and had independently done as well.

Step 2. Install battery and measure voltage. A bit over 12VDC measured:


Step 3. Try and start the car. You see the dash light for a short while and then just die when key turned.

 

[Pskhaat]

Step 4. Measure the little jump battery voltage. Looks the same a bit over 12VDC:


Step 5. Hook up the jump battery to the clamp bolts. Note no additional torquing or squeezing or anything on the terminal blocks. Just a simple hook up. Et voila she starts. Hesitates, but then starts.


I'm sure I need to address the alternator, and maybe other things down the line. In due time. But why would the addition of a small jump battery not changing anything else magically make everything start when the main battery is freshly tested and charged?

 

[Pskhaat]

You do you, but I would 100% swap in a different battery.

Dude, I mean maybe. I love these 84-monthers and Toyota refuses to warranty as it tests out fine. My own little computer-controlled charger says it tests 100%. Wroth the try I thin.

 

[tmxmotorsports]

Dude your battery is done and is either not letting the alternator charge it due to a bad cell or you alternator is bad also. Put a different battery in it start it up and then check for 14.5 or close to it to verify the alternator is charging.

 

[Pskhaat]

Dude your battery is done and is either not letting the alternator charge it due to a bad cell or you alternator is bad also. Put a different battery in it start it up and then check for 14.5 or close to it to verify the alternator is charging.

It's basically new (March), and Toyota refuses to warranty. Any thoughts?

I have another Group 24 (I'll want a 27) charging in the garage now.