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  #16  
Old June 5th, 2019, 23:09
CLSegraves CLSegraves is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Kind of, not really. I put my BTS back on after everyone said that was likely the problem. Didn’t solve it. I finally said “f* it” and ignored the issue. After a few weeks of random 19v errors, the problem magically went away and hasn’t come back. Nothing changed in that timeframe so no clue what to attribute the issue to.
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  #17  
Old June 6th, 2019, 04:00
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

The OBD-II PCM will trip the Check Gauges light and flip the voltage gauge to either end of the scale if the PCM notes a charging problem.

If the dashboard voltage gauge shows 9 volts there is almost always an alternator issue. If the dashboard voltage gauge shows 19 volts, there almost always a connectivity issue, most often corroded battery lugs/terminals, internally corroded battery wires, or a loose connection in the charging system.



Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Battery lugs should be almost a shiny light gray, not dull or black. Copper wires should be copper color, not black or green. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt to.

Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

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Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....

Last edited by Tim_MN; June 6th, 2019 at 04:16.
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  #18  
Old June 6th, 2019, 09:46
BAXJDAY BAXJDAY is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Tim, Thanks for the check list. I have confirmed most of these already. Not long ago I replaced all my heavy gauge cables. In general I keep my rig well maintained. I'm always being accused of having to "clean of a Jeep" :-)

CLS, I have not been driving the XJ in fear of burning up circuits. In my 30 years as an IT analyst, I have seen many weird things just come and go with no reason. I refer to this as the Pixie Dust solutions.

Is there any risk to the electric circuits driving with this high a voltage?
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  #19  
Old June 6th, 2019, 09:54
md21722 md21722 is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

The only time my Jeep has ever ran with the gauge pegged like this was a faulty Optima Yellow Top.
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  #20  
Old June 6th, 2019, 09:55
md21722 md21722 is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

The Yellow Top had shorted internally. Replacing the battery fixed the issue.
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  #21  
Old June 6th, 2019, 10:15
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Quote:
Originally Posted by BAXJDAY View Post
Is there any risk to the electric circuits driving with this high a voltage?
Excessive charging voltage can burn up any 12 volt component or 5 volt OBD-II sensors. This includes the PCM, TCM, and the am/fm stereo.

If all diagnostics and trouble shooting is negative, the very last thing to suspect is failure of the voltage regulator circuits inside the PCM.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
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Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....
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  #22  
Old June 6th, 2019, 10:40
CLSegraves CLSegraves is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Quote:
Originally Posted by BAXJDAY View Post
Tim, Thanks for the check list. I have confirmed most of these already. Not long ago I replaced all my heavy gauge cables. In general I keep my rig well maintained. I'm always being accused of having to "clean of a Jeep" :-)

CLS, I have not been driving the XJ in fear of burning up circuits. In my 30 years as an IT analyst, I have seen many weird things just come and go with no reason. I refer to this as the Pixie Dust solutions.

Is there any risk to the electric circuits driving with this high a voltage?
Itís not high, the computer is being stupid. When I had my issues, I had a digital voltmeter hooked to the battery and it was solid 13.8 volts.
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  #23  
Old June 6th, 2019, 11:39
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

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Originally Posted by CLSegraves View Post
Itís not high, the computer is being stupid. When I had my issues, I had a digital voltmeter hooked to the battery and it was solid 13.8 volts.
Maybe try checking the voltage at the PCM?
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  #24  
Old June 6th, 2019, 11:54
CLSegraves CLSegraves is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

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Maybe try checking the voltage at the PCM?
Why? My battery is hooked to the alternator by 1/0 gauge cable. If anything, PCM would show lower voltage.
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  #25  
Old June 6th, 2019, 12:12
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

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Originally Posted by CLSegraves View Post
Why? My battery is hooked to the alternator by 1/0 gauge cable. If anything, PCM would show lower voltage.
You could have a bad ground from the battery to the chassis, it's best to check for codes and see what voltage the pcm is seeing.
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  #26  
Old June 6th, 2019, 17:49
BAXJDAY BAXJDAY is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

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Originally Posted by md21722 View Post
The Yellow Top had shorted internally. Replacing the battery fixed the issue.

Did the voltage tests (post 2 post, running idle) read proper on that yellow?


I do have a blue top. But it's showing 12.7 P-P.
Maybe I'll swap out a newer red I have in the CJ to see if that makes a difference.
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  #27  
Old June 6th, 2019, 18:00
BAXJDAY BAXJDAY is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Quote:
Originally Posted by Tim_MN View Post
Excessive charging voltage can burn up any 12 volt component or 5 volt OBD-II sensors. This includes the PCM, TCM, and the am/fm stereo.

If all diagnostics and trouble shooting is negative, the very last thing to suspect is failure of the voltage regulator circuits inside the PCM.

That was fully suspected early on. So I swapped in my brand new spare PCM.
Didn't make any difference. Both PCM's are telling the generator to output over 19v to the charging system. Thinks it has some great load.


Also when I load it down with everything I got. The gauge will center out.
Ass soon as I turn the lights, or AC off, it pegs out again.
Here is a good example of the behavior:


https://www.youtube.com/watch?v=5Vw-D6ulWcI
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  #28  
Old June 6th, 2019, 18:17
BAXJDAY BAXJDAY is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Quote:
Originally Posted by sidewaysstarion View Post
You could have a bad ground from the battery to the chassis, it's best to check for codes and see what voltage the pcm is seeing.

I am suspicious of this being a grounding issue. By codes are you referring to the check engine light error (OBD-II) codes? I'm not getting any.
I saw someone mentioned scanning the BTS via the OBD. Perhaps I need to understand my reader better. See what it will see while the engine is running.
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  #29  
Old June 7th, 2019, 03:59
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

If the dashboard voltage gauge shows 19 volts, there almost always a connectivity issue, most often corroded battery lugs/terminals, internally corroded battery wires, or a loose connection in the charging system. The PCM does not see correct charging levels due to the poor quality connections, and it thinks the voltage needs to be full blast.
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Quote:
Originally Posted by bimmerjeeper

Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Quote:
Originally Posted by soyjer

Tim MAY be 100% correct, but why would a person automatically pick him as the expert .....

Last edited by Tim_MN; July 14th, 2019 at 05:54.
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  #30  
Old June 7th, 2019, 04:03
md21722 md21722 is offline
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Re: Voltage Gauge read 19 volts - Digital Meter says 14.2

Quote:
Originally Posted by BAXJDAY View Post
Did the voltage tests (post 2 post, running idle) read proper on that yellow?


I do have a blue top. But it's showing 12.7 P-P.
Maybe I'll swap out a newer red I have in the CJ to see if that makes a difference.
I don't think I ever put a multimeter on it. I do remember coming out to a dead battery. To jump it, we had to disconnect the battery terminals and jump off the cables alone. When we put the cables back on the battery it showed 19V. The headlights and interior lights were not brighter than normal so I doubt the voltage was as high as the gauge read. Replacing the battery with a decent Auto Zone Gold battery fixed the issue.

After that I noticed other places I'd go would have stacks of Optima batteries and everyone said the same thing - they'd never buy another one. It seems like the original Optima's were good batteries. I bought one because the 3/4 ton Dodge Cummins had one that was 9 years old and still worked. But by around 2007-2008 the quality had plummeted. Apparently when they moved the plant to Mexico they had a bunch of QA issues that were supposedly fixed. I just buy the Auto Zone ones anymore. There are lots of Auto Zones and Auto Zone typically has the best (longest) hours. They fail within a couple of years usually just inside the pro-rated warranty so I get a new one for free.
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