Electrical Gremlins

pewpew82

pewpew82

Caught the Bug
Searching for strength to keep from burning this bitch to the ground. I know I'm missing something dumb.

2010 JKU. Battery has been checked by 3 different machines, shows good. Alternator tested 4x. All good. Replaced cable ends on battery cables at the battery. Cleaned all bulkhead connectors under hood.

Battery light comes on and stays. Battery voltage low and battery voltage high codes somehow. Charging at 14.8-15.2 while idling and low revs. Shut it off and now won't crank.

Wtf am I missing?
 
pewpew82 said:
Searching for strength to keep from burning this bitch to the ground. I know I'm missing something dumb.

2010 JKU. Battery has been checked by 3 different machines, shows good. Alternator tested 4x. All good. Replaced cable ends on battery cables at the battery. Cleaned all bulkhead connectors under hood.

Battery light comes on and stays. Battery voltage low and battery voltage high codes somehow. Charging at 14.8-15.2 while idling and low revs. Shut it off and now won't crank.

Wtf am I missing?
Click to expand...
Sounds like a bad alternator. 14.8 seems high. Regardless, battery light being on is almost always a charging system concern.
 
pewpew82 said:
Searching for strength to keep from burning this bitch to the ground. I know I'm missing something dumb.

2010 JKU. Battery has been checked by 3 different machines, shows good. Alternator tested 4x. All good. Replaced cable ends on battery cables at the battery. Cleaned all bulkhead connectors under hood.

Battery light comes on and stays. Battery voltage low and battery voltage high codes somehow. Charging at 14.8-15.2 while idling and low revs. Shut it off and now won't crank.

Wtf am I missing?
Click to expand...
Did they test the crank of the battery?

I have a 2010 and went thru something similar, battery tested great at 3 different auto parts stores, removed the alternator and took it to a local shop for a rebuild but they called me before I got home and told me it was fine.

I stopped at O'Rielly's when a different employee overheard me asking the guy that checked the battery if he had any other ideas on what to check since the alternator and the battery tested fine.
The employee asked the guy I was talking to if he checked crank output, we both looked at him like "what you talking about Willis", He grabbed a different testing machine, hooked up and had me crank (not start) 3 different times and sure enough, the crank side of the battery was dead.
He told me it's not too common, but it explained why the battery acted dead at random times but had full voltage and the charge readings were all over the place at the battery but the alternator was fine.
It was also a 1-year-old battery, replaced it and no issues since.
 
The cranking amps were tested at 642 of 690.

The alternator was tested 4 times and always passed no problem.

I'm going to clean all the grounds tomorrow and check the ignition switch. If the issue remains, I will drive and get the crank test and have the alternator checked while idling if I can get it to fire.

Any other suggestions, I'm open to trying at this point.
 
pewpew82 said:
The cranking amps were tested at 642 of 690.

The alternator was tested 4 times and always passed no problem.

I'm going to clean all the grounds tomorrow and check the ignition switch. If the issue remains, I will drive and get the crank test and have the alternator checked while idling if I can get it to fire.

Any other suggestions, I'm open to trying at this point.
Click to expand...
624 of 690 seems on the low side, I can't recall what mine was, but did they tell you the volts while cranking?
My cranking amps were low, and the voltage was below 9 volts, I remember this because I thought it should be closer to the actual stored voltage but was told it should be closer to 10 while cranking.

I've since bought a battery tester off Amazon; I've used it more often than I thought I would.
 
Update for anyone interested:

Made a new ground strap for the hood/firewall/block flat strap and installed it, but it didn't help.

Borrowed a GOOD tester from a friend and tested the battery and electrical system several times, every time tested good.

Got my test light out and found a draw while the battery was unhooked. Started reseating everything in the fuse box starting with the relays to find the draw. I found 3 different fuses not properly seated in panel and reseated everything else.

No more issue. Jeep has run perfectly since saturday. I still have a small draw, but not enough to drain the battery. I will continue to look into this, but the charging system seems to be ok.
 
So, MY problem seems to be cured. My sister has a 2016 that the battery died. She will be stopping by tomorrow to borrow my scanner and I want to be prepared.

"When jumping her Jeep, it starts and idles just fine. When adding throttle input, the pedal does absolutely nothing. The sensor has been replaced on the pedal as well as the throttle body."

I think she is overlooking something simple, I'm going to have her clean the terminals. Since I found the fuse issue on mine, I will have her check all of those as well.

Any other ideas from the pros here?
 
My experience with our two Jeeps is when a battery starts giving out, the system throws all sorts of codes and develops gremlins that go away when a new battery is installed.
 
I'm pretty sure she will need a new battery.

I'm told it's stuck in limp mode.

Is there a reliable way to calibrate the throttle position sensor manually, without a tuner? Or is it even possible?
 
pewpew82 said:
I'm pretty sure she will need a new battery.

I'm told it's stuck in limp mode.

Is there a reliable way to calibrate the throttle position sensor manually, without a tuner? Or is it even possible?
Click to expand...
This is what I did after replacing the TBS on my JKU and do so each time after the battery has died.
It seems to respond better after doing this.

1) Insert ignition key and turn to "ON" (not start).
2) Wait for all idiot lights to go out. Check Engine Light may remain on.
3) Slowly depress the accelerator pedal all the way to the floor.
4) Slowly release the accelerator pedal until it's all the way back up.
5) Turn the ignition key to "OFF".
6) Start the engine.
 
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