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Discussion Starter · #1 ·
Starting about a week ago, I have been getting the "Power System Service Urgent" message + red triangle + battery light for 7-15 seconds every 10-15 minutes. It's been hot here - 80F + each time I've been out, not sure if that is a contributing factor given the bay temp.

Battery is a brand new Group H7 AGM (1000CCA) holds 12.0/12.3V (with/without load) engine off rock solid and 14.35V on.

2005 T5 AWD with 87,000 miles. It's the Denso SC2 (36001463 aka 30667103, 30737529, 30659369, 8603496, 36050028), going for $375+$30 core on Tasca.

The code is ECM-830B (Faulty Communication), NOT the ECM-8300 (ACM Faulty), or ECM-830C (Faulty Signal) or ECM-830D (Signal too high). I had the entire engine apart recently (head replacement), and this makes me wonder if I have a pinched/loose wire somewhere or if it is just another manifestation of a failing ACM.

When (years+miles) have you had to replace your alternator?
 

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That's a bit early for the alternator (the vast majority go way over 100k). I think your hunch may be correct. "Faulty communication" seems key. Is the battery temp sensor plugged in (easy one to forget)? That sensor adjusts the charging rate with temperature.
 

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I guess I was one of the unlucky ones to have my alternator go bad so early, but definitely look over all your connectors like pczeilon said.

When mine started to go I had all sorts of things going wacky ... key errors, radio had no sound sometimes, possibly even killed my rear door module. I think I caught it just in time though. The VIDA screenshot below was with the car running, but at 13.7V. After the new alternator it's like 14.5+, and no more dtc's.

 

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Discussion Starter · #4 ·
That's a bit early for the alternator (the vast majority go way over 100k). I think your hunch may be correct. "Faulty communication" seems key. Is the battery temp sensor plugged in (easy one to forget)? That sensor adjusts the charging rate with temperature.
Yeah - checked the batt temp sensor, according to ViDA it's at 2.8v at 23c or there abouts even when the warning is displayed. It follows the exterior and intake temps closely, so I think it's working. BTW that sensor has it's own codes:
<pre>
CEM-4F30 Battery temperature. Signal too high
CEM-4F31 Battery temperature. Signal too low
CEM-4F32 Battery temperature. Faulty signal
CEM-4F33 Battery Temperature Faulty Signal
</pre>

I did re-seat the ACM and the ECM connectors and there was no visible corrosion. Unlike beachnut my voltage is good and I don't have a billion other codes (though I've seen this before when the acc belt snapped).

I'm no longer under the 100k+ delusion - I lost the timing belt tensioner at 83k (and subsequently, head swap), pretty much exactly 10 years from the day she rolled of the line. It wouldn't surprise me if it's bad, I was just wondering how common it is and at what age/miles.

I'm thinking that it could just be an issue in the little microcontroller sitting on the alternator, but I'm not willing to risk taking it apart without having a spare. Plus it's only 30k miles away from it mechanically failing, might as well do it now.

Unfortunately SSS just started so I'm gonna have to read through that massive thread and figure out what to do there. Just a lot all at once :mad: guess I can't say anything after replacing the head ;)
 

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My 05 s40 started the red triangle flash at 74k miles couple months ago, it's ten years old so I wasn't complaining too much.
 

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Same here. 06 T5 AWD with 80k on the odometer. Was replacing the alternator until the tensioner snapped off but have the new one in and plan on getting it done after work.
 

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sorry for the n00b question and hijacking the thread, but how does one should go about testing the battery and alternator to see if they're still providing the correct voltage?
 

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There can be a little more to it than this but here is a quick test. Measure resting voltage, should be in the range of 12.5. Take another reading with the car running. Should be 14.5 or so. Let us know what you get. I'd only be concerned if you are more than .5 volts off of those figures.

You should also "load test" the battery. Pull the fuel pump relay or something to prevent the car from starting. Now measure voltage while you crank it for 10 seconds. Think about replacing the battery if voltage drops below 10. Definitely if it goes below 9.5.
 

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^ hey thanks for the tip :) should i just use a volt meter and measure the voltage at the battery terminals (once when the car is off, and once when it's running)?
 

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^ hey thanks for the tip :) should i just use a volt meter and measure the voltage at the battery terminals (once when the car is off, and once when it's running)?
That will work.
With the car off also measure voltage between the battery posts & then between the battery cable ends (battery connected). If those two numbers don't match remove, clean & reinstall cables. Not a bad idea in any case. Add some dielectric or Vaseline to your newly cleaned connection to keep it that way.
 

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ok, i have an analog voltmeter which is not the most accurate. the battery was at 12V when the car was off. with the car on, the voltage was 14.5V. there was also no voltage drop when i used battery terminals or cable ends. i guess that means (assuming that my voltmeter is accurate) that the car battery is okay?
 

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12.0 volts is quite low for resting voltage. Each cell is actually 2.1 volts so a perfect, fully charged battery would be 12.6. I'm guessing you have a dying battery. I really doubt it would pass the load test.
Charging voltage is spot on.
 

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Discussion Starter · #13 ·
Forgot to update:

Ended up replacing the alternator. The manual specifies this part is "SC2 14V/150A"... was a PITA to get the correct part from Tasca (almost $600!!!). For reference, the old alternator was marked:

Denso 3m5t-10300
30667103
12v 150a

New alternator was marked:

Volvo 36001463
Denso 104210-5
12v-150a

Took about 3hrs with VIDA. Light went right out, the stalling issue went away. All is well.
 
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