Help Diagnosing a Problem Please

[KV4Runner]

Evening

1998 4 Runner v6.

Bought a new battery last month and drove her about 3x. Today I went to take her out and it didnt start, click nothing. No lights, no juice whatsoever.

Now, last month when I replaced the battery the connections on the battery were checked, cleaned, tightened so nothing loose there.

One of the times I drove it, at night, the lights were dim, I rev the engine they brighten, I let it idle they dim a bit, rinse repeat.

Think it's the alternator? Any ideas on how to diagnose?

Thanks in advance!

 

[jgue467]

Take your vehicle to where you bought the battery. They should provide a free battery/alternator test to determine if either is the weak link. It is normal to some degree to have the headlights dim a bit when idling compared to moving on down the road but not much. Also depending on how far you drove those 3x, it may not have had much time to make up the juice used to start plus often batts come only 1/2 to 2/3 charged to begin with, not much driving = not much charging? Luck. :cowboy:

 

[octanejunkie]

I suspect a short somewhere that caused much of a drain, but what was said about low initial charge and mild use would contribute to your experience.

If it will take a jump, run it over to the parts store and get the charging system and battery checked like [MENTION=75316]jgue467[/MENTION] said

 

[enapa]

Start the truck. Disconnect the negative terminal. If it dies it is the alternator.

 

[KV4Runner]

Thanks for the help all.

So I jumped her and had a 13.5v reading while it was running. My research said that if my alternator was working properly, I would have 14.2. However, an "old timer" that worked on cars all his life told me 13.5 with no load was normal and I had no load when I tested.

The resting voltage was 12.4 yesterday and 12.4 today after sitting overnight. Im going to monitor it to see if the battery has a parasitic drain.

 

[HiLife]

I would think if was your terminals (loose, corroded, etc). You said you already check that out and the connections was clean good and tight.
So I would say it's a parasitic drain somewhere, or you blew 1 of the diodes in the diode trio. Where you got your battery installed should be equipped to check your alternator, rectifier and regulator for you.

 

[Lug1]

13.5V when running is not normal, not good, I disagree with the oldtimer.

Should be around 14.2V.

Unless you have an exotic issue (bad wiring), this sounds like an alternator slowly going bad.

Used Denso (OEM) alt's on ebay are ~$70. I'd put a tested alternator in your truck as first step of diagnostic. Then test the voltage while running, if it's up to 14+V, you found the problem (and fixed it).

 

[KV4Runner]

I would think if was your terminals (loose, corroded, etc). You said you already check that out and the connections was clean good and tight.
So I would say it's a parasitic drain somewhere, or you blew 1 of the diodes in the diode trio. Where you got your battery installed should be equipped to check your alternator, rectifier and regulator for you.

Thanks, but what is the Diode Trio?

 

[phattyduck]

13.5V when running is not normal, not good, I disagree with the oldtimer.

Should be around 14.2V.

Unless you have an exotic issue (bad wiring), this sounds like an alternator slowly going bad.

Used Denso (OEM) alt's on ebay are ~$70. I'd put a tested alternator in your truck as first step of diagnostic. Then test the voltage while running, if it's up to 14+V, you found the problem (and fixed it).

Charging voltage of the alternator depends on temperature. Hotter = lower voltage.

From the Toyota manual:
13.9−15.1 volts with engine running at 2000 rpm and 25°C (77°F)
13.5−14.3 volts with engine running at 2000 rpm and 115°C (239°F)

That temperature is at the alternator rectifier/regulator.

That said, 13.5 at idle should be a bit higher if the engine is the only load (lights off, brakes off, stereo off, HVAC off, etc.). I'm also a bit surprised that the battery resting voltage is 12.4 - it should be closer to 12.6.

-Charlie

 

[Lug1]

That said, 13.5 at idle should be a bit higher if the engine is the only load
-Charlie

Yes, with the ranges you've specified - I don't recall a case in a 12V automotive system when with all accessories off, the alt' provided 13.5V and there were no complaints from the driver.

In my small corner of the world, 13.8V and lower implies (possible) charging issue.
It's either 14.1V+ , or a problem (creative electrical modifications non withstanding).

I am curious as to what OP finds to be the culprit though.

 

[KV4Runner]

Thanks for the help all - much appreciated!

Further testing this morning around 60 degrees F:

First test 12.3V
Started the vehicle (started quickly)
14.5V at idle, ran it at idle for 3 minutes
14.47 at idle after 3 minutes
Turned off, resting voltage 12.76
Turned on front lights for 60 seconds
12.29V
Waited 30 seconds
12.35V

 

[KV4Runner]

About 5 hours later:

Sitting 12.3V
Started up, 14.47V
Drove 3 mins up the road to the package store, turned off. Started back up, drove home 3 mins, 13.8V when parked but running.
Turned off, 12.7V.

 

[jgue467]

About 5 hours later:

Sitting 12.3V...

This is somewhat low for 5 hrs after use. Should be at least 12.7 volts especially if new.

I may have overlooked it but did you have the batt and charge system load tested? :cowboy:

 

[KV4Runner]

This is somewhat low for 5 hrs after use. Should be at least 12.7 volts especially if new.

I may have overlooked it but did you have the batt and charge system load tested? :cowboy:

Not yet, maybe Ill go tomorrow (Sunday).

 

[KV4Runner]

Before starting 12.43V
Went on the highway for a 20 minute trip, parked, 12.7V.
At dinner, drove 20 minutes home on the highway, parked, turned off, 12.7V.

 

[octanejunkie]

What happens if you pull a battery cable while the car is running?

Sent from my Nexus 5X using Tapatalk

 

[Rusted.Runner]

Looking for help with my own issue!

2000 runner 3.4 290ish kms.

Problem started as minor cyl 3 missfire, so changed plugs and wires to no avail and then changed coil on cyl 3 as well. no change to the problem.

Problem seems to have gotten worse CEL's for multiple missfires, truck runs like crap and seems to have lots of hesitation. Was told maybe bad fuel but seems a bit much for bad fuel.

So maybe injector or fuel pump?

Thanks for any help!

 

[octanejunkie]

This looks familiar Lol

What codes you getting?

Sent from my Nexus 5X using Tapatalk

 

[Rusted.Runner]

PO303 was the intial code then it just turned to PO404 then multiple cyl missfire/random missfire

 

[KV4Runner]

An update. I purchased one of those battery tender products, the NoCo Genius from Amazon and let it do it's thing.

Since then my battery has been reading perfectly. Even after a week of sitting around in 40-50 degree temps, it ready 12.4.

Thanks all for your advice!