Jeep WK Weird Voltage / Alternator? Help! - Page 2 - JeepForum.com
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post #16 of 33 Old 01-07-2018, 08:06 PM
azzkicker
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Is your battery bolted down securely? If your battery can hop up and slam down when you hit bumps, it will kill the battery young.


07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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post #17 of 33 Old 01-08-2018, 07:05 AM
KUJeeper82
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How long do you all think you could run a normal battery at 15.2 volts before it frys? My PCM is shot, and I'm holding off on replacement for a month or two and I've noticed my running voltage is typically 14.9-15.2 depending on load (AC/Lights etc.). Not two months ago it was typically 14.5V. Voltage at the OBDII port is typically 0.1-0.2V lower (expected due to harness losses?)

The change occurred after I cleaned all the corrosion off the PCM and repaired with dialectric and JB Weld...
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post #18 of 33 Old 01-08-2018, 09:34 AM
azzkicker
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Originally Posted by KUJeeper82 View Post
How long do you all think you could run a normal battery at 15.2 volts before it frys? My PCM is shot, and I'm holding off on replacement for a month or two and I've noticed my running voltage is typically 14.9-15.2 depending on load (AC/Lights etc.). Not two months ago it was typically 14.5V. Voltage at the OBDII port is typically 0.1-0.2V lower (expected due to harness losses?)

The change occurred after I cleaned all the corrosion off the PCM and repaired with dialectric and JB Weld...
Lead acid batteries are relatively forgiving of over-voltage, and that's really only about a volt more than normal. I'm assuming glass mat (AGM) batteries behave similarly to lead/acid (they are lead/acid, just the acid is absorbed). What happens is the resistance in the battery spikes up dramatically as the designed voltage is reached, so even though you have a voltage delta, you have very little current into the battery.

I'm not suggesting it's a good thing to over-volt, but of the types of batteries I designed chargers for, lead/acid is the most forgiving and li-ion is the least forgiving (very dangerous, as they do not increase resistance with higher voltages).

I'd be more worried about your electronics than your battery, but I can't back that up with any facts.

I don't know what you repaired with JB weld, but is it possible you've gotten some JB weld to create a slight short across two terminals or two traces? I notice sometimes I end up with almost hair like strings of JB weld that get places I didn't intend.

07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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post #19 of 33 Old 01-08-2018, 12:14 PM
KUJeeper82
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Quote:
Originally Posted by azzkicker View Post
Quote:
Originally Posted by KUJeeper82 View Post
How long do you all think you could run a normal battery at 15.2 volts before it frys? My PCM is shot, and I'm holding off on replacement for a month or two and I've noticed my running voltage is typically 14.9-15.2 depending on load (AC/Lights etc.). Not two months ago it was typically 14.5V. Voltage at the OBDII port is typically 0.1-0.2V lower (expected due to harness losses?)

The change occurred after I cleaned all the corrosion off the PCM and repaired with dialectric and JB Weld...
Lead acid batteries are relatively forgiving of over-voltage, and that's really only about a volt more than normal. I'm assuming glass mat (AGM) batteries behave similarly to lead/acid (they are lead/acid, just the acid is absorbed). What happens is the resistance in the battery spikes up dramatically as the designed voltage is reached, so even though you have a voltage delta, you have very little current into the battery.

I'm not suggesting it's a good thing to over-volt, but of the types of batteries I designed chargers for, lead/acid is the most forgiving and li-ion is the least forgiving (very dangerous, as they do not increase resistance with higher voltages).

I'd be more worried about your electronics than your battery, but I can't back that up with any facts.

I don't know what you repaired with JB weld, but is it possible you've gotten some JB weld to create a slight short across two terminals or two traces? I notice sometimes I end up with almost hair like strings of JB weld that get places I didn't intend.
I'm less concerned with the rest of the vehicle electronics, my research indicates these trucks will start throwing alternator codes above 16V.

Regarding the PCM repair, I took great effort to make a barrier between the JB Weld and electrical contacts. The plastic surrounding the contacts may still hold residual acid traces however. I also could have introduced foreign materials into the sealed compartment of the PCM during cleaning an neutralization. Attached is a picture of post cleaning and post repair. Unfortunately I didn't think to take one before removing from the vehicle. It was horrible looking though with acid aluminum plastic slag all over it.
Attached Thumbnails
20171229_170929_1515438742261.jpg   20171229_170934_1515438774135.jpg   20171230_102317_1515438813106.jpg   20171230_102311_1515438854002.jpg  
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post #20 of 33 Old 01-08-2018, 02:20 PM
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Dude what happened to that PCM??? Looks like the part you fixed had experienced some kind of heat damage earlier?
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post #21 of 33 Old 01-08-2018, 03:21 PM
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That's what happens when your PCM lives under the battery in a CRD. I've seen ones where the top case has been eaten through! I remove my battery and battery tray once a year and give it a good wash down with Bicarb Soda and fresh water to prevent this.

The alternator on a CRD has an internal regulator so I would be looking at that before a PCM, alternator is a Valeo TG17C028
https://www.ebay.co.uk/itm/12-Volt-A...-/172952016096

http://plus.google.com/u/0/+DownunderJeep/posts/p/pub
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post #22 of 33 Old 01-09-2018, 08:13 AM
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Originally Posted by lxr200 View Post
Our Alternators are externally regulated. Our voltage regulators are built into our PCM's so if thats whats bad, its not the alternator its the PCM. I did just go to Advance auto, they said the battery was fine, but the alternator showed "Open Phase". Not sure if that has anything to do with the voltage regulator in the PCM or just the Alternator itself. I did get a new alternator though, I'll be trying to put it in after work tomorrow, I'm hoping it takes care of it.
That means the alternator is bad. Open phase means that something broke in the alternator itself; bad winding, bad diode, bad regulator...etc. It is not putting out clean smooth wave power, but dirty power

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post #23 of 33 Old 01-09-2018, 02:38 PM
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Quote:
Originally Posted by Clarkyau View Post
That's what happens when your PCM lives under the battery in a CRD. I've seen ones where the top case has been eaten through! I remove my battery and battery tray once a year and give it a good wash down with Bicarb Soda and fresh water to prevent this.

The alternator on a CRD has an internal regulator so I would be looking at that before a PCM, alternator is a Valeo TG17C028
http://www.ebay.co.uk/itm/12-Volt-Al...-/172952016096
Thanks!

How hard is this to replace? I hear replacing the alternator is a major PITA
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post #24 of 33 Old 01-10-2018, 11:15 PM Thread Starter
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Originally Posted by azzkicker View Post
My first two thoughts are bad connections or bad battery. The fact you have some fancy thing in the dash telling you 2 volts less than your meter on the battery, leads me to think bad grounds or bad connections.

Nobody, in the history of automobiles, has regretted cleaning battery connections and grounds to the engine and body. Look for green corrosion on the wire at the terminal. That is very bad. You have to start cutting until you get to clean copper and put a new terminal on.

Also look for those grounding straps on the engine and exhaust pipes. Take those off and clean them. I like to clean everything and then spray it with battery terminal protector. The other option is to use dielectric grease, but the spray is easy. I go through about a can every decade.
Ok, So I installed the new alternator, I'm not getting as bad voltage drops as I used to, ex. when using windows, rear defrost, heater, etc. so My alternator was def on its way out if not all the way gone. BUT I'm still getting ~16 - 16.7 volts or so at the battery when my vehicle is running (about 13.4 volts when vehicle is off) I had the battery tested @ Advance Auto Parts and they said the battery was fine. I cleaned the connector at the alternator before re-attaching the wire. My battery terminals had no corrosion, and my body ground was tight and didn't seem to have any corrosion. My radio (Maestro RR which gives me trouble codes and vehicle data) that shows the voltage and digital gauges, that could be showing lower voltage (12.5 - 15v) because its through data and not actually reading the voltage itself, like its just reading what the PCM is throwing at it - but I'm not quite sure - its kind of like monitoring with a code scanner - but in my radio.
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post #25 of 33 Old 01-11-2018, 04:08 AM
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maybe your PCM has a cruddy connection, so it's reading low and driving your alternator high. Your PCM thinks your battery is low. It tells the alternator what to do,

07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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post #26 of 33 Old 01-11-2018, 04:15 AM
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You may have some corrosion in the little wires themselves, near where all that damage was. Can you replace that chunk of harness?

07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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post #27 of 33 Old 01-11-2018, 04:27 PM Thread Starter
lxr200
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Originally Posted by azzkicker View Post
You may have some corrosion in the little wires themselves, near where all that damage was. Can you replace that chunk of harness?
What damage? There was no damage.
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post #28 of 33 Old 01-11-2018, 10:39 PM
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Originally Posted by lxr200 View Post
What damage? There was no damage.
I was referring to the acid burned, melted looking area, and the rusty, crusty area from your photo. I call that damage.

When corrosion starts at a connection, it can work down the wires so that even when the connection is clean, there's a lot of resistance in the corroded wire. I've had that most often at a battery terminal, where you cut the corroded terminal off, but the wire is still green instead of clean copper. If you don't cut it back until you get to clean copper, you never get a good connection on your new terminal.

That's what I was speculating about.

07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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post #29 of 33 Old 01-12-2018, 07:24 AM
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Quote:
Originally Posted by azzkicker View Post
I was referring to the acid burned, melted looking area, and the rusty, crusty area from your photo. I call that damage.

When corrosion starts at a connection, it can work down the wires so that even when the connection is clean, there's a lot of resistance in the corroded wire. I've had that most often at a battery terminal, where you cut the corroded terminal off, but the wire is still green instead of clean copper. If you don't cut it back until you get to clean copper, you never get a good connection on your new terminal.

That's what I was speculating about.
That messed up PCM was a completely separate Jeep that someone posted on their similar problem.


As for the OP; is there any problems with lighting or flickering bulbs, or over bright lights? If no problem is there, and the alternator and battery test good, leave it alone

06 4.7L QT-II, RC 2", 255/70-17 Revo2, 1.5 spacers, SC Tuner, coilover shocks
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post #30 of 33 Old 01-12-2018, 08:15 AM
azzkicker
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I don't think I'd ignore that much over-voltage. I'd be looking for whatever is causing a 2V difference between what the PCM is seeing, and what is actually at the battery.

Maybe unplug the PCM, clean anything ugly, and plug it back in. If there's a bad connection on whatever pin is bringing the power to the PCM, or the ground from the PCM, that would seem to explain why the PCM is seeing less voltage than the battery.

07 WK 5.7 QD2, 4" lift, 33X10" tires, two M8000s
ARB twin air,Dual AGM group 49, sliders and skids
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