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Unread 07-01-2013, 10:01 AM   #1
Siva283
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Join Date: May 2011
Location: Falling Waters, WV
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Code 47 any electrical guru's out there

I will be testing this tonight with a new alternater from the 98 durango currently parked next to it but I am at work right now and this is really bothering me. As some of you may remember Que and Pete for instance. I had an electrical short a few months ago. Thought it was all straight. SO I finally give the dirty girl a bath yesterday and I guess it made her mad. I take it for a drive after cleaning the 3 tons of mud off and 15 minutes into the ride the check engine light comes on. I look over and my alt is not charging at all. Nothing Nadda Zip Zilch. Doesnt matter if I rev the engine up absolutly no change. I am getting code 47 Battery undervoltage. Now again as a few know I have a huge battery 1250 CCA at 32 degrees. I cant still start the jeep run lights and everything off the battery so I know its not the battery. At first after I fixed the electrical issue it seemed to charge about 1.5 volts high going by the gauge but a multimeter read 14.8. Lately it has been charging at 14 - 14.2. I dont know why but I have this feeling it may be the notorius ECM issue. Hopefully I am wrong. Does anyone know the way to troubleshoot the ECM side of it. Obviously I will replace the alt since I have a perfectly good free one I can use temporarily since noone seems to want to buy the awesome 5.9 durango I have. But if I find this doesnt fix the issue what is the best way to test the ECM control circut. Do I just hook a multimeter up to the field wires and look for voltage. Would it really be that simple. I already miss being able to call Que up and ask him it made life much easier.

Hopefully he will be back in a few weeks.

__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 07-01-2013, 12:28 PM   #2
tdewit
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Read here
http://www.jeepforum.com/forum/f12/y.../#post15617300
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Unread 07-01-2013, 12:44 PM   #3
Siva283
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That link does me no good. It does not answer my question. I am trying to find proper test procedures for the ECM circut. I am also not getting 41 which is the field coil. I am only getting 47 which is battery under voltage. My battery however is fine. I have discovered this through my not so scientific test. The Alt is putting out 0 voltage. That tells me my field coil is completly toasted or I have an ecm issue. I am trying to find out the proper way to test the ECM charge circut.
__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 07-01-2013, 02:34 PM   #4
VenomousMaximus
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The PCM puts power on the Dg/Vlt wire to the Alternator field wire from pin C25 while the engine is running and then grounds the Dg / wire at pin B10 of the PCM to turn the field on & off to maintain desired charge state.
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Unread 07-01-2013, 02:41 PM   #5
VenomousMaximus
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Quote:
Originally Posted by VenomousMaximus View Post
The PCM puts power on the Dg/Vlt wire to the Alternator field wire from pin C25 while the engine is running and then grounds the Dg / wire at pin B10 of the PCM to turn the field on & off to maintain desired charge state.
Also try a wiggle test at the connectors watching for changes & make sure all the pins in the connector are clean & not corroded or lose.. make sure to always use dielectric grease at all connections.
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Unread 07-01-2013, 03:43 PM   #6
Siva283
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Quote:
Originally Posted by VenomousMaximus View Post
Also try a wiggle test at the connectors watching for changes & make sure all the pins in the connector are clean & not corroded or lose.. make sure to always use dielectric grease at all connections.
Que taught me well Dielectric grease on everything. I checked connectors and tried the wiggle test with no change. Should I test field voltage at the PCM or at the connector on the alt? I am assuming I should ground the meter to battery when I do this test and only use the positive probe on the pins or at the connector? Thanks for the input that was the type of info I was looking for
__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 07-01-2013, 07:19 PM   #7
pete1991YJ
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You could do it by process of elimination. First I would measure how many ohms does the field coil have, with the als completely disconnected and everything off. If the reading is zero or infinite, then you know the field coil is shot but the ECU circuit maybe still good. The ECU circuit should be putting out a certain DC voltage IIRC it was less than 12 volts but I don't recall the exact number.

In a pinch (emergency) you can always feed a field coil directly from the batt positive thru a brakelight bulb - the bulb will limit current to a safe amount usually around 5 Amps.

Yeah, I know ytou wish it was Que
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Unread 07-01-2013, 07:25 PM   #8
pete1991YJ
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BTW you can stick a 4-ohm 20-watt resistor (or similar heavy-duty) across the field wirew without conmnecting them to the alt, this will fake the computer into thinking the alt is there! You could try this and see if the error code goes away, or use it for further testing purposes. Less than 5 bux at radio shack.
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Unread 07-01-2013, 08:21 PM   #9
Siva283
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Lol you know your loved too pete. I was worried I haven't seen you in awhile. I tested my fueld circut earlier. The ecm slowly climbed from 5 volts to 10. I am guessing it was increasing voltage to the field trying to get the alt to charge. The alt is putting out zero still though. I only read battery voltage everywhere I tested. The battery is good though I just stuck it in the durango and it fired it up and pulled 14 while the durango was running. If the people coming to see it tomorrow don't buy it I am stealing its alt. and throwing it in the jeep to see what happens. Since its a 98 and all. Its the 5.9 so if it doesn't sell soon I sense a neq motor for the jeep in the 5.9 flavor

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__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 07-01-2013, 08:28 PM   #10
pete1991YJ
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If the alt was still putting zero even with field voltage then there's definitely6 a prob. Just for giggles, try checking the output with the volts set for "AC". Its one way to check for a bad diode. I've been in school for CNC machine shop and programming so its been kinda hairy lately... the only time I have is very early in the AM.
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Unread 07-01-2013, 08:31 PM   #11
Siva283
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Quote:
Originally Posted by pete1991YJ View Post
If the alt was still putting zero even with field voltage then there's definitely6 a prob. Just for giggles, try checking the output with the volts set for "AC". Its one way to check for a bad diode. I've been in school for CNC machine shop and programming so its been kinda hairy lately... the only time I have is very early in the AM.
Hmmm I will give that a shot tomorrow its time for a shower and a few shots to sleep well. Been a bad day. Luckily the jeep is not my only vehicle anymore so I don't have to be so rushed. As always pete its great to hear from you and nice to see you around. I really was wondering if something happened as you are missed when your not here as well.

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__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
Siva283 is offline   Reply With Quote Quick reply to this message
Unread 07-04-2013, 02:47 PM   #12
Siva283
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Join Date: May 2011
Location: Falling Waters, WV
Posts: 3,698
It was the field coil new alt and new battery and its charging perfect. My battery also had an internal short that reared its head when it got warm.

Sent from my SPH-L300 using JeepForum
__________________
1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
Siva283 is offline   Reply With Quote Quick reply to this message
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