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Battery No Charge??


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when i first start my sts, the battery icon lights up in red and the info reads battery no charge. it only does this till i drive the car for about 10 seconds. it will stay on however if i dont drive the car and let it idle. i already changed the battery and tested the altenator with that thing you plug into the cigarrette lighter. i am begining to wonder if i should just ignore it. any ideas?

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Run the OBD II codes and see if that tells you anything. Here's how:


-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Here is what the FSM has to say about what conditions set the "Battery No Charge" message:

The Instrument Panel Cluster (IPC) monitor the alternator L-terminal input on Connector C1 terminal "A9". If the alternator is not charging, ground is applied to the L-terminal. If the alternator is charging, the L-terminal will be at ignition voltage. The IPC uses this input to detect DTC IP 1911 (Alternator 'L' Terminal Problem). If it is detected, the "BATTERY NO CHARGE" message will be displayed. This will occur whenever the L-terminal input is "LOW" and the engine has been running over 400 RPM for more than 2 seconds.

As Jim suggested, read your codes. I bet you will find a P1911.

Here is the FSM page on DTC IP 1911:


As you can see from reading that page and looking at the wiring diagram, the "BATTER NO CHARGE" message (and DTC 1911) will set when the "L" terminal is shorted to ground. In plain english, on the back of your alternator there is a wiring harness and connector attached to it. The connector has 2 wires, designated the "F" and "L" terminals. The "F" terminal reports the output voltage back to the computer (PCM). The other wire, the "L" terminal, reports the alternator output voltage to the Instrument Panel Cluster (IPC).

Somewhere along the pathway from this connector on the back of the alternator, to your IPC, the wire has shorted to ground. This could be caused by several things. Here is what I would check.

#1. Check to make sure it's not a wiring harness short to ground from rubbing, or corrosion buildup on a connector. Get under your car, and disconnect the clip to the alternator. Then disconnect connector C101. As you can see in the wiring diagram, this is the ONLY connector between the alternator and the IPC, everything else should be solid wire. I have personally seen NASTY corrosion on my C101 connector that caused several codes to set, including THIS ONE!! (DTC IP 1911).

Connector C101 is located under the hood, by the driver's side shock tower. You need to remove the big black plastic shroud covering the fuse/relay center. C101 is mounted onto a piece of black plastic, right by the shock tower. It is rectangular. Here is what it looks like, and what each pin in the connector is assigned to:


As you can see, on C101, terminal "L" is a red wire, on circuit 225, which is the same as what is shown in the DTC IP 1911 diagram, and it carries a reference voltage from the voltage regulator on the alternator to the IPC. After disconnecting the halves of C101, I would take a multi-meter, and probe between terminal "L" on C101, and terminal "L" on the disconnected connector from the alternator. First check for continuity. Then check for resistance, it should be very low, like less than 5 ohms. Anything higher indicates high resistance in the wire somewhere between the 2 connector ends. Next, check for shorts to ground by setting the multimeter to continuity mode, and probe one end of the multimeter to battery ground, and the other to terminal "L" on C101. You should NOT have continuity. If you do, then find the short to ground.

Technically, you should do this same probing from the other half of the connector on C101, to the connector on the back of the IPC. But removing the IPC to get to this connector is a pain in the butt, and I really doubt this is where you problem lies. It is far more likely that a short to ground would occur along the length of wire from the back of the alternator up to C101.

Look carefully at where the wires insert into the pins of C101. I had nasty green corrosion on several of my pins. Some of the wires were so corroded, they just fell out entirely when I handled C101. I ended up stripping the wires, re-pinning them, and all my related codes went away!

If ALL that checks out OK, then the next thing I would do is:

#2 - Check the alternator! It may just be that the voltage regulator is failing and shorting out to ground - not uncommon. You would not see this with a simply cigarette lighter plug-in alternator analyzer, as those just check system voltage. For a complete alternator diagnostic, take it to a shop or pull the alternator and take it in to be bench tested at the auto parts store. You may just have a bad alternator.


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To add:

If the alternator checks bad, have the original alternator rebuilt by an AC Delco starter and alternator shop. They are in most cities. They will repair the alternator properly. It will outlast a chain store remanufactured junker with a lifetime warranty and the price will be much less than the chain store junker.

'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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  • 4 years later...

i have been battling this problem for months now, finally i found the info i need to fix it right here. thanx

if this L terminal wire Is in fact shorted can i just run a new wire from the c101 connector to the alternator harness?

like from the c101 to the alternator = new wire??

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