Intermittent Electrical Problems and Failure to Charge (1 Viewer)

[Danman]

Hey Cruisers, The latest issue with my truck is that several of the warning lights on the cluster including the battery light intermittently come on. It seems like when the lights are on, the alternator does not charge the battery and I do not get where I am going. I have replaced the battery and alternator very recently. The Transmission was changed recently and the O2 sensor wire was mauled by the shop and "repaired". I am wondering if it may be a bad ground that might be causing the alternator to not charge the battery. Or possible loose wire. I have uninstalled the aftermarket radio. It seems like there may be a short because the truck discharges when sitting. Help...

 

[jonheld]

Classic bad alternator/no charge.
This could also be a bad cell in the battery dragging down system voltage.
Did you replace it with an OEM unit or aftermarket?
Have you put a voltmeter across the battery terminals with and without the engine running?

The battery appears to be discharged after sitting because it is not being charged.

 

[REKCUT]

2nd the question of checking voltage. Got to be first step in this process. Should have 12+ with truck off and at least high 13's with it running. This will give you direction you need to proceed

 

[mudgudgeon]

Could be bad alternator,
bad alternator connection/plug,
bad ground,
bad fusible link,
bad alternator brushes,
Basically, something is bad

 

[Danman]

I will check the voltage while it is running. But is has a new alternator and battery. I am thinking a ground or short because the other two warning lights are coming on at the same time as the charge light. 3 lights...... If is was just the alternator, wouldn't it just be the battery light coming on. It seems like when the lights are off it does just fine and the charge stays above 12v. Then when the lights come on it MAY stop charging and begins to drain the battery. Make sense? How many grounds are there and where are they located? Thanks guys.

 

[Danman]

Yelp....Any hints where the ground cable/cables are located? Any other Ideas about where a short would occur that would prevent the battery from charging and or cause all three warning lights to come on ? I replaced the fusible links with new ones. I have also replaced the NSS and the round harness looks pretty clean near the PHH. It seems to be pretty random. It will run fine for a while and then the lights will all three come on at once. . I will recheck the alternator connections and test with a voltmeter when I get a chance on Wed. . thanks.

 

[REKCUT]

This is the problem with just jumping around. Start with voltage meter. I have installed bad alternators and bad batt before. Start at the end and work you way upstream

 

[Danman]

This one has a link to a '96 wiring diagram but mine is a 94 so it may be slightly different. It shows 2 grounds. One near the rear of the vehicle and one near the firewall. I will check these as well.

Ground wire locations

does anyone know where the ground wires are located for the stock straight 6 motor because when I idol it start to go low then catch back up plus it's not really running to full power potential and I can't understand why .... any ideas

forum.ih8mud.com

 

[inkpot]

Probably should ok f replaced the fusible link first if yur gunna play Parts Swap Party. Its easiest, and its cheapest, @ < $20.

 

[jonheld]

I will check the voltage while it is running. But is has a new alternator and battery. I am thinking a ground or short because the other two warning lights are coming on at the same time as the charge light. 3 lights...... If is was just the alternator, wouldn't it just be the battery light coming on. It seems like when the lights are off it does just fine and the charge stays above 12v. Then when the lights come on it MAY stop charging and begins to drain the battery. Make sense? How many grounds are there and where are they located? Thanks guys.

If you do a cursory search of "christmas tree lights" you will find many many many posts regarding your issue. Most times it is due to a faulty alternator or something in the charging system. A faulty alternator will illuminate the charge lamp as well as multiple other dash lamps.
Don't go down the primrose path on this. Check the simple things first.
Put a meter across the battery terminals with the engine running. A healthy alternator will be putting out approx 14.4 VDC.
A healthy battery at rest (engine not running for several hours) should read 12.7 VDC.

 

[Tools R Us]

... But is has a new alternator ...

Define this, have seen disappointing results from krylon overhaul, parts store rebuilds. In this case the go to is DENSO 210-0181, by brand and part number.

I am thinking a ground or short because the other two warning lights are coming on at the same time as the charge light. 3 lights...... If is was just the alternator, wouldn't it just be the battery light coming on.

Standard deal for an alternator problem.

It seems like when the lights are off it does just fine and the charge stays above 12v.

12V is not charging, looking for ~14V.

How many grounds are there and where are they located? Thanks guys.

Does it start and run? If there were significant ground problems, would also expect other problems, like, slow or no starter response, etc.

Without resting and running, volt readings, we are shooting in the dark.

 

[Danman]

Thank you guys so much for the input. It wasn't charging because it was arching at the positive terminal of the alternator. I am not sure if it was a rust issue or what but it heated up the plastic insulation around the terminal quite a bit. It is working fine for now and I am stoked that it isn't anything more tedious. Cheers.

 

[JerseyCruiser]

I have the same lights randomly coming on as well, then I turn the headlights on/off and they go off. I have no other electrical issues and the battery hasn’t died even though it’s been like this for a year. I replaced the brushes 40k ago, so that with the fact the battery is good leads me to believe it’s not the alternator.

 

[jonheld]

I have the same lights randomly coming on as well, then I turn the headlights on/off and they go off. I have no other electrical issues and the battery hasn’t died even though it’s been like this for a year. I replaced the brushes 40k ago, so that with the fact the battery is good leads me to believe it’s not the alternator.

As previously stated, without supplying voltage readings with and without the engine running, all you're doing is guessing.

 

[JerseyCruiser]

As previously stated, without supplying voltage readings with and without the engine running, all you're doing is guessing.

With all accessories off and engine running I get about 13.5-13.7V across the battery terminals. I was able to get the alternator light to come on and at that time it showed about 12.7 V across the battery terminals. I couldn’t only achieve close to 14.4 V when I put the RPMs up excessively with accessories off.

 

[Tools R Us]

With all accessories off and engine running I get about 13.5-13.7V across the battery terminals.

Charging.

I was able to get the alternator light to come on and at that time it showed about 12.7 V across the battery terminals.

Not charging.

I couldn’t only achieve close to 14.4 V when I put the RPMs up excessively with accessories off.

Charging voltage depends on factors like, load, battery charge/condition, etc. Watch the voltage or the dash lights, wiggle the alternator wires and fusible links, can you make it fail, if so maybe a poor connection.

 

[JerseyCruiser]

Charging.



Not charging.



Charging voltage depends on factors like, load, battery charge/condition, etc. Watch the voltage or the dash lights, wiggle the alternator wires and fusible links, can you make it fail, if so maybe a poor connection.

Tools,

The 13.5-13.7 V was charging with all accessories off. 12.7 V was charging with accessories off and the alternator light lit on the cluster. I wanted to wiggle the wires and fusible links but no one was home to observe the cluster while I was under the hood. I'm still wondering why every time the alternator light comes on I can reset it instantly by turning the headlights on and off. I'll try wiggling the wires and report back.

Thanks
George

 

[JerseyCruiser]

Before I could diagnose the problem further today the alternator light was coming on every few seconds and would pin the volt meter at 18 V and all of my dash lights were super bright and the AC fan was racing of course from being over powered. I'll try to get under the hood this weekend but it sounds like the voltage regulator is shot, I had the same symptoms with my old FJ62

 

[JerseyCruiser]

UPDATE: I replaced the alternator yesterday with a Denso 210-0181 everything is back to normal.