Voltage Gauge read 19 volts - Digital Meter says 14.2

C

CLSegraves

NAXJA Forum User
Location
Lawrenceburg, KY
2001 XJ, 4.0 with a 160 amp Durango Alternator that idles at 13.8VDC (confirmed with volt meter). 3 month old Optima Yellow top battery. Battery, alternator and ground (both from battery to frame and frame to engine block) cables are 2/0 gauge audio grade cables. No cranking issues. I've been running this setup for almost a year without any issues before now.

Yesterday I was driving home and the voltage gauge in the cluster pegged at 19VDC. I was on the freeway so it took me time to get off and get to where I could stop. By the time I did, the gauge had returned to normal. Started driving home and it happened again (19VDC while cruising, back to normal on stopping).

This morning I hooked a digital volt meter to the battery (my battery is under my rear seat) and drove to work. As expected, got on the interstate and the voltage gauge pegged at 19VDC. Volt meter confirmed rock solid 14.2VDC the entire time. When I stopped, the volt meter showed 13.8VDC and the voltage gauge returned to normal. This indicates to me that the alternator, voltage connections, and battery are good. So I'm at a loss.

Any input?
 
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 is almost always a connectivity issue, often corroded battery lugs/terminals, internally corroded battery wires, or a loose connection in the charging system. Make sure the battery charging temperature sensor in the bottom of the battery tray is not malfunctioning, and that the battery sensor wire plug and wire harness are not damaged or corroded.

Gauge cluster grounds are unlikely to be the root cause of the issue.
 
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Tim_MN said:
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 voltage gauge shows 9 volts there is almost always an alternator issue. If the voltage gauge shows 19 volts, there almost always a connectivity issue, often corroded battery lugs/terminal, internally corroded battery wires, or a loose connection in the charging system. Make sure the battery charging temperature sensor in the bottom of the battery tray is not malfunctioning, and that the sensor wires/wire harness are not damaged

Gauge cluster grounds are unlikely to be the root cause of the issue.
Click to expand...

I cut the battery temp sensor out (coiled the plug and wrapped it into the harness to prevent a short) months ago when I relocated the battery. Perhaps that’s the issue (I’d be surprised it just now started complaining)?
 
CLSegraves said:
Should say “CUT the plug” (not coiled).
Click to expand...

There are a couple of things that do not add up.

You cut the battery sensor out? My 1996 XJ will immediately turn on the check engine light it is disconnected. Maybe the 2001 is different.

An independent volt meter connected across the battery shows 14.2 volts when the engine is up to speed. I would say that is a perfect voltage reading. The aim is to get 14.3 to 14.5 volts.

I think you need to look somewhere else outside of the alternator and/or the PCM for the high voltage reading on the gage. I agree with Cal. You may have a grounding/wiring problem going to the gages. Those could be difficult to trouble shoot.
 
techno1154 said:
There are a couple of things that do not add up.

You cut the battery sensor out? My 1996 XJ will immediately turn on the check engine light it is disconnected. Maybe the 2001 is different.

An independent volt meter connected across the battery shows 14.2 volts when the engine is up to speed. I would say that is a perfect voltage reading. The aim is to get 14.3 to 14.5 volts.

I think you need to look somewhere else outside of the alternator and/or the PCM for the high voltage reading on the gage. I agree with Cal. You may have a grounding/wiring problem going to the gages. Those could be difficult to trouble shoot.
Click to expand...

Yes, I cut the battery sensor out and it's entirely possible that it has thrown a code. However, my check engine light has been on for almost 2 years now ever since I swapped in the manual transmission (the ECU is still an automatic ECU). I haven't attempted to "fix" the issue as I'm planning an LSx swap by the end of the year.

That was my feeling (that the alternator is working as it should based on the 14.2 VDC). Interestingly (thinking about my issue tonight), after I went wheeling last weekend. On the way home, I started getting "glitching" of the speedometer. I'd be driving along and the speedo would suddenly "bump" up or down, hold, come back to actual speed. This glitch would happen every few minutes, but this issue hasn't returned since we got home. I'm wondering if this could also have been from a lose/poor ground in the cluster.
 
CLSegraves said:
Yes, I cut the battery sensor out and it's entirely possible that it has thrown a code. However, my check engine light has been on for almost 2 years now ever since I swapped in the manual transmission (the ECU is still an automatic ECU). I haven't attempted to "fix" the issue as I'm planning an LSx swap by the end of the year.
Click to expand...

You can scan the OBDII port to see if the battery temperature sensor is throwing a code, among other the codes.
Guess your state doesn't doesn't require emission testing. A lighted CEL light would be an automatic fail in states that test.
 
lazyxj said:
You can scan the OBDII port to see if the battery temperature sensor is throwing a code, among other the codes.
Guess your state doesn't doesn't require emission testing. A lighted CEL light would be an automatic fail in states that test.
Click to expand...

Yes, we do. I would have to assume this rig has not been on the road.
 
I hooked the battery temperature sensor back up this afternoon and drive the vehicle. Same result as before, so it's not the lack of a sensor that was the issue (didn't think it was as I had been driving the vehicle this way for the past 6 months).

We do have emissions here, I'm just between tests (not due again until Feb 2020). I'll either fix the issues or do my LSx swap before it comes up for testing again.
 
Was this resolved? My '97 XJ has started the same bad behavior.
I've tested everything. Battery good at 12.7v, BTS draws 9k resistance (fairly new also), all connections good and clean, new alternator 3 months ago.
I disconnected my winch cables and compressor circuits to eliminate any issues there. Checked all my fuses and breakers, eliminated my bad auto door lock circuit by pulling the fuse. I had a spare PCM, finding out the voltage regulator goes bad on those, I swapped out my spare. Still the same problem.
If I have to troubleshoot the gauge, I'll leave that to the experts. But any other ideas I might be overlooking? I'm about to tag out.
 
I should mention that the voltage test at the battery while running is consistent with the gauge reading. 14.2v upon start, 19.3v when acting up. Which makes me think the gauge is OK and reliable.
 
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.
 
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)

.
medium800.jpg
 
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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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