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2002 Deville
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Discussion Starter #1
I had the battery indicator light on when I recently purchased my used 2002 Deville Base. I replaced the old alternator with a brand new AC Delco (non remanufactured) alternator. I replaced the old battery with a class 79 battery. This was thought to alleviate any of those parts as factors in this indicator light/message.

I get the typical battery not charging, service charging system message. Furthermore I had to take my engine out entirely and do a full head bolt to head stud conversion from Northstarperformance and installed new MLS Racing Headgaskets :yup:; while doing this I cleaned all ground cables and ground surfaces to make perfect contact.
I am at a full and entire loss now after reading every forum I can find talking about this issue, with no resolve as it appears. The engine is installed and smooth as butter, as I replaced all gaskets including coolant bridges, all hoses, inspected and rewrapped all wiring harnesses and connectors, replaced all injectors, replaced fuel-transmission-oil filters, all vacuum hoses, direct ignition coils, 02 sensors, spark plugs, water pump, thermostat,and definitely the intake plenum coupling,
next week I will be changing the Transmission Torque Converter Clutch Pulse Width Modulation Valve as I have those PCM P0741 and P1860 codes being thrown. I have replaced several other items- however I cannot get to the bottom of this annoying charging system issue. I will also note that I swapped two other "remanufactured" alternators before resting with a brand new one by AC Delco.

So first thing first- I want to alleviate this Battery not charging, service charging system problem. :want:

Have we not figured out a permanent solution to this ever occuring problem? If we have where are we turning to solve the issue?:confused:
 

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2002 Deville
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7 Posts
Discussion Starter #3
I have just traced the entirety of the positive cable from battery to the front and rear fuse boxes with zero flaw in the cable; same stands true with the battery ground cable. No damage.
 

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2011 DTS super traveller
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126 Posts
Check you engine ground to the firewall or consider running another ground from the engine to the firewall.
 

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2002 Deville
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7 Posts
Discussion Starter #5
Interesting. I have yet to identify an engine ground cable that runs to the firewall on my 2002 Deville.

I have a ground cable that runs front the passenger side frame below and in front of the a/c condenser, to the alternator. Where about will I locate the "firewall" ground that should be grounded from the engine? I will fire up the shop lights as I speak to start the locating of this ground cable/ running a new ground from the engine to the firewall if this will help to solve this problem. Again, where am I supposed to find this "pre-exsisting" engine to firewall ground cable?? Furthermore is this alternator to body frame enough to ground the engine block?
 

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86 Bronco, 74 Ford LTD,1999 Deville, 1977 Coupe Deville
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305 Posts
Are you changing out all of these alternators because they are not charging the battery? Or just because of the message?
 

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2002 Deville
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7 Posts
Discussion Starter #7
I have just finished adding an additional ground cable that runs from the engine to the frame of the body with no difference in symptoms. I am testing the cable with my multi-meter to determine ground connectivity, with both sides of the cable showing 14.8 volts on the meter. What can possibly be tripping this computer into determining that my vehicles charging system is ineffective???? I cannot let this elusive symptom outwit us Cadillac owners!!

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I replaced the alternators for different reasons.
Here is the scoop with the alternators. I had the service charging system light on at first, common sense points to the alternator with most all applications; so I started there.

I went to the auto recycler in my home-town to grap a used alternator- well hindsight is 20/20 and I knew better, but that alternator was SHOT!

So I ordered a remanufactured AC Delco and got it all hooked up and installed only to discover that the voltage regulator was putting out like 17 volts to the battery and I was then triggering a "voltage too high" symptom message on the instrument display.

I then immediately ordered a "NEW" AC Delco alternator and installed that- which is still in there and charging to a consistent 14.8 volts on the regular.
After all of this turbulence, I not only discover that my original alternator works just fine- but that I had a pressurized coolant problem, whereas I then focused on the head stud and racing gasket job.

Now it is driving like a boss, but I have this really elusive charging system problem that I cannot diagnose alone.
 

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2011 DTS Premium w/1SD | 1999 Deville Base (RIP @179K Miles)
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404 Posts
I think on the alternator there's a special wire that controls the load output of the alternator. Whenever the car draws extra electrical load, the PCM puts voltage on this wire and that makes the alternator supply more power. Look for the schematic of the alternator circuit and check for continuity on that wire.
 

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1992 Fleetwood S&S Hearse, 1993 Buick Roadmaster
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567 Posts
Make sure you don't have a blown fuse to the alternator. Sounds simple, but I've watch people replace their battery, alternator, starter, and battery cables, just to find out they had dropped $300 on parts when all they needed was a buck or two worth of fuses.
 

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2002 Deville
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Discussion Starter #10
So it appears I may have my solution

Ok. So after RomoRock3r responded I decided to actually look up schematics for what I need to identify in the system.

I came across the schematics and diagrams that I am going to post up for future references and came to a conclusion about what must be causing this issue in the "charging system". :suspect:

This problem will occur because of a problem with wiring/connection, alternator, or the pcm. :yup:

If you find that this battery light and error in charging messages still are present. This is the way that I have gone about diagnosing further into the system.

There are three wires involved with the alternator plug. I will focus on the orange and red wires with my diagnosis. First it is important to check a fuse that is a Hot fuse "#38 DIM FUSE 10A- Dash Integration Module (DIM), Generator " *(see diagram). This fuse sits under the back seat in the fuse compartment on a 2002 Cadillac Deville.
View attachment 296241


After verifying if that fuse is the problem your next step is to...

Disconnect the alternator plug. Start and run the engine. Using a multi-meter check for voltage at the RED wire in the wiring harness plug, this contact should have 5V while disconnected from the alternator and the engine running.

Next plug the connector back into the alternator and with the engine running check to see if there is still 5 Volts or 0 Volts.
If there is not 5 volts, verify at this time that the wire is not broken or exposed to minimal connections; which cannot handle a voltage load. If you have 5 Volts here the problem is then indicating the alternator has the issue. If you have 0 volts.. move on..:want:

If the Red wire is showing 0 Volts when Plugged into the alternator, it is important to determine if the red wire has any damage or flaws in the length of the wire. Furthermore the wire needs to be tested for continuity at this point. Backprobe the red wire at the PCM on the Clear connector at pin 40 (see photos and diagrams). If continuity is compromised then check the red wire is not shorted to ground and replace the entire red wire connection or reroute this wire from the pcm connection to the alternator connection if you find the damage.
View attachment 296257 View attachment 296265 View attachment 296273 View attachment 296249

If you have 0 volts, at this time JUMP 5 volts to the alternator from a Gray wire (5V) of the Throttle Position Sensor (TPS) to the Red connection in the alternator plug. Plug the alternator wires back into the alternator and test the jumped connection by starting the vehicle and running the engine. If the alternator is charging when jumped with 5 volts , this indicates that the Powertrain Control Module (PCM) needs replaced.:bigroll:

The Red wire should stay close to 5 volts when the alternator is charging. Verify battery voltage on the orange wire in the alternator plug. The alternator should not be pulling the jumped wire to ground, and if the alternator is pulling the jumped wire to ground then this indicates that the alternator needs replaced- recommending that an OEM alternator to be used.

If everything you tried tested good, move on to check and verify power and ground supplies to the PCM. If that all verifies okay- replace PCM :bighead:

So I had zero volts when I tested the red connector while it was plugged into the alternator and the engine was running. Then I jumped 5 volts from the TPS and voila.. No more battery lights or charging system messages. So tomorrow I am in the shop to replace my PCM and determine if this is the fix for me. I will post my results good or bad :suspense:
 

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2002 Deville
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Discussion Starter #11
So it appears I may have my solution

Ok. So after RomoRock3r responded I decided to actually look up schematics for what I need to identify in the system.

I came across the schematics and diagrams that I am going to post up for future references and came to a conclusion about what must be causing this issue in the "charging system". :suspect:

This problem will occur because of a problem with wiring/connection, alternator, or the pcm. :yup:

If you find that this battery light and error in charging messages still are present. This is the way that I have gone about diagnosing further into the system.

There are three wires involved with the alternator plug. I will focus on the orange and red wires with my diagnosis. First it is important to check a fuse that is a Hot fuse "#38 DIM FUSE 10A- Dash Integration Module (DIM), Generator " *(see diagram). This fuse sits under the back seat in the fuse compartment on a 2002 Cadillac Deville.
View attachment 296241


After verifying if that fuse is the problem your next step is to...

Disconnect the alternator plug. Start and run the engine. Using a multi-meter check for voltage at the RED wire in the wiring harness plug, this contact should have 5V while disconnected from the alternator and the engine running.

Next plug the connector back into the alternator and with the engine running check to see if there is still 5 Volts or 0 Volts.
If there is not 5 volts, verify at this time that the wire is not broken or exposed to minimal connections; which cannot handle a voltage load. If you have 5 Volts here the problem is then indicating the alternator has the issue. If you have 0 volts.. move on..:want:

If the Red wire is showing 0 Volts when Plugged into the alternator, it is important to determine if the red wire has any damage or flaws in the length of the wire. Furthermore the wire needs to be tested for continuity at this point. Backprobe the red wire at the PCM on the Clear connector at pin 40- Generator Turn on Signal RED (see photos and diagrams). If continuity is compromised then check the red wire is not shorted to ground and replace the entire red wire connection or reroute this wire from the pcm connection to the alternator connection if you find the damage.
View attachment 296257 View attachment 296265 View attachment 296273 View attachment 296249

If you have 0 volts, at this time JUMP 5 volts to the alternator from a Gray wire (5V) of the Throttle Position Sensor (TPS) to the Red connection in the alternator plug. Plug the alternator wires back into the alternator and test the jumped connection by starting the vehicle and running the engine. If the alternator is charging when jumped with 5 volts , this indicates that the Powertrain Control Module (PCM) needs replaced.:bigroll:

The Red wire should stay close to 5 volts when the alternator is charging. Verify battery voltage on the orange wire in the alternator plug. The alternator should not be pulling the jumped wire to ground, and if the alternator is pulling the jumped wire to ground then this indicates that the alternator needs replaced- recommending that an OEM alternator to be used.

If everything you tried tested good, move on to check and verify power and ground supplies to the PCM. If that all verifies okay- replace PCM :bighead:

So I had zero volts when I tested the red connector while it was plugged into the alternator and the engine was running. Then I jumped 5 volts from the TPS and voila.. No more battery lights or charging system messages. So tomorrow I am in the shop to replace my PCM and determine if this is the fix for me. I will post my results good or bad :suspense:
 

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2002 Deville
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Discussion Starter #12
I fixed the problem!!! DONE

Following up after my speculations, ideas, checks -- with my solution.

I ended up replacing/reprogramming a new PCM at the local GM dealer in my city today. Stood in the shop with my tech and observed it all go down. Conversing about the problem and other issues on the Cadillac.

Once the programming was finished I still had my battery light and charging error messages!

Looking at my alternator schematic and talking with the tech about seeing 5Volts on the plug unhooked, then 0 Volts when Hooked up directing me to the PCM as the culprit..
He says did your hot orange wire read voltage?
I said no.. it had zeroooooooooohhhhhh shit! :nono:
...
HOT:devil: WIRE!!!

YA- :coffee:

So I checked my orange wire... but it didnt register in my brain that it was a 'HOT' 12 volt wire... and zero is not the volatage I needed :cookoo:

So I leave the dealership with A-NEW-OTHER PCM programmed for my Deville, anticipating getting home and checking continuity in my orange wire... :gun:
Only to find that there is absolutely NO continuity in the orange wire :bulb:

ANYWAY to make my sob story short :violin:

I Hard wired a 12Volt, fused supply directly from my 12volt post in the engine bay to my tapped orange alternator plug wire :ride:

Yay- no more battery light and charging error messages!

Now anyone with this problem can either use my information for once... and forget about all the other :~blah:
:spamkill:
 

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86 Bronco, 74 Ford LTD,1999 Deville, 1977 Coupe Deville
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305 Posts
Now that you can relax a bit, are you still going to track down the break in your original hot wire?
I will be removing the engine on my 99 deVille one day & I'd like to hear ( read) how you went about it. Out the top? Bottom? What equipment you used , lessons learned.
I'd like to buy a two post lift someday, but it keeps getting put off for one reason or another.Seems like doctors want ALL of my money these days! Heh..Heh
Now that your an expert, are you going to be on the lookout for more overheating Northstar caddy's?
They seem like candy to me.

Thanks, Brad
 

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2007 Cadillac STS-V Black On Black
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1,428 Posts
Wow, you did a lot of work to that engine, must drive like brand new! Glad you got it fixed :thumbsup:
 

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2003 deville
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1 Posts
Re: I fixed the problem!!! DONE

I have 2003 deville doing the same thing. where does the other end of the orange wire go?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The thread has been dead for over 4 years. You may not receive an answer.

Welcome to CF !!! Best to start your own thread for your particular car and problem - use these old threads for knowledge reference.
 

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Look into the tensioner assembly as well ... As a Store manager at a Auto parts store I see this constantly.. where customers come in and want to replace alternators and batteries because light keeps flashing.. the tensioner is in place to pull voltage from alternators to charge battery.. if the tensioners bearings are shot you will be running on cranking amp/ or reserved min instead of Cold Cranking amps.. to inspect the tensioner you will need to idle vehicle in park and watch for tensioner arm to move more than few centameters.. (typically you should only see the movment with a timing light) along with hearing the RPMS rise and fall.. are also good indicator that your tensioner and belt are worn out and need replacing... In the event you also have to replace alternator or battery would be due to long term voltage shortage and it will drain your battery
 
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