Battery-Alternator Warning Light - Where should I look for damage?




Also, do the Autozone/repair place have to connect the LIN bus?
My guess is that they do not.
I'd expect that they use a motor and belt to turn the alternator, and connect the alternators main output to a load, and measure.
Does the battery voltage go up at all after you start the car?
Good luck!
The first test (at the alternator/starter shop) used a less sophisticated machine which may have had only a battery post connector. The shop was dark and I had to walk in from bright sunlight. It was difficult to see and at the time I was only looking for a yes/no report. If I had known it would be important I would have looked more closely.
The battery voltage does not go up at all.
I am planning to test the voltage at the alternator and then follow Russell’s suggestion and test with the original voltage regulator. I may also disconnect the data line and see what happens.
I want to make sure I am not just throwing parts at the problem, but a rebuilt alternator may be required.
Thanks to both of you for your feedback.
Last edited by KevinH2000; Jul 3, 2020 at 12:36 PM.
A faulty regulator or poor brush to slip ring connection and you will have no charge.
Your Alternator problems are from the work done on it not from the initial short circuit.




It appears the alternator failed to energize.
Here are some pictures of the voltage regulators as I had installed them:
Original voltage regulator:
Original voltage regulator after I reinstalled it.
Replacement voltage regulator
If anyone sees any flaws in the way I installed the voltage regulators, please point them out.
At this time, it appears my options are:
1. Reinstall the alternator with the original voltage regulator and hope for the best. Since hope is not a plan, I don't think I will try this unless someone identifies a mistake in my regulator installation..
2. Find a used alternator. I may have a source. The problem with my source is that the car is someone's backyard and accessing the two bolts on the bottom of the alternator may be difficult without raising the car. I won't make an attempt unless I am sure we can raise the car safely. Also, a used part that has been sitting on a non-running car outdoors for over a year may not function properly.
3. Buy a rebuilt alternator. The local MB dealer will price match the Internet sellers, but this is still the most expensive option.
Again, feedback is welcome.
If the car is a necessity, then don't buy cheap stuff for the car.
If money is an issue, drop/reduce your $$$ cable, $$ phone bill/phone, etc.
If the car is a "toy", then is some cheap part going to risk a breakdown or a bad failure?
If the alternator goes, and you have to drive more than ~10 miles in the winter at night, good luck making it home.
If it's snowing, and you're driving isolated roads, you better pray for cell phone service.
On the other hand, if the radio goes, then BFD! :-)
Also, define "expensive".
Is a $25 use once tool "expensive", if it saves you time, and reduces repair risk?
How about $2,000+ for a rebuilt and installed tranny? Is that expensive? Yes!!

You can get a new alternator on Amazon for $106.
Premier Gear PG-13954 Professional Grade New Alternator
You can buy the OEM Alternator for ~$239
Bosch AL0810N New Alternator
When I did my "restoration" of my prime-shape ~80K miles 2005 C230K, the Bosch alternator above is what I bought.
As soon as I bought my car, I wanted to replace the POS timing chain. I know about costs/risks analysis very well.
Of course :-), the timing chain replacement turned into a "might as well do this now and not worry about it later" non-minor "restoration".

I even replaced the intake and intercooler. Both get oil inside, that's not good for efficiency(HP or gas mileage). Also, I had specific goals in areas, that I wanted to meet/come-close to - for the heck of it. :-)
Plus, I now have a backup alternator, in case the one in the car dies.
Fwiw, it helps storing car parts, if people have a basement, like I do. :-)
Otherwise, I understand how keeping a lot of car parts isn't a good option for people.
I plan on my 2005 C230K staying with me for a while.
So, I think in term of 10++ years.
My '86 Mustang is ~35 years old. I know it'll outlast my 2005 C230K. And, it'll also likely outlast my new hybrid that I'll get in 1-2 years (well past this zombie apocalypse BS stuff happening now!).
I trust my Mustang more than any new vehicle.
Especially any over-priced POS "status symbol" vehicles.
https://jalopnik.com/if-range-rovers...ill-1728727599
https://www.thedrive.com/news/34389/...-into-oblivion
Imho, if you're planning on keeping the vehicle a long time (imho, no reason not too, unless it gets an accident), then only buy new MB parts (if you can).
Note: The parts market for a MB is different than for a car like a Corvette, Mustang, Camaro. For my Mustang, I was able to buy a new alternator that is better than anything that Ford made.
Rockauto also has a number of options
https://www.rockauto.com/en/catalog/...generator,2412
Note that the Bosch rebuilt costs more than a new Bosch alternator.
That's because Rockauto knows in order to survive, it has to match/come-close to Amazon/Summit/etc in price for commonly sold parts.
Btw; as for the Dealer, in this case - run.
They only sell a re-manufactured alternator with a retail price of ~$800 (with the core charge).
https://parts.mercedesbenzofdurham.c...80280GZ64.html
$733.00 + $64.00 core charge + S&H. If you want your $64 back, figure ~~$20 in shipping.
Fwiw this is a way for the Dealerships/MB to make a lot more money when they service cars.
Clearly, it costs the dealership/MB far less for a re-manufactured alternator, than for a new one.
The re-manufactured alternator should last for ~~140K miles. So, it's not like the dealership/MB is screwing the person with an "unreliable part". Last over ~100K for an alternator isn't "too bad".
Good luck!




If I have to replace it, my approach to car repair is similar to yours. I bought my C230 with a goal of keeping it until my daughter finished school. At the time that was 3 years and an estimated 40,000 miles of commuting. I paid $4300 for the car and that seemed like a decent return on investment. I met my goal and I continue to enjoy the car. I have made some updates including C63 AMG front seats and upgraded infotainment system. I am planning to keep the car for at least another 3 years which would put me at about 200,000 miles. I like manual transmission vehicles. In that context finding a replacement with the right combination of comfort, fuel economy, performance and a stick is likely to be difficult.
I am annoyed at myself for making a mistake. I don’t want to waste money fixing it, but I don’t plan to cut any corners. A poor-quality alternator would just compound my previous error. If I confirm that I need to replace the alternator I plan to buy a Bosch. I am not sure whether I will buy new or rebuilt. I will check all the sources you listed.. The current alternator is a rebuilt Bosch (it was replaced by a previous owner.). The starter also has a Bosch rebuild label on it.
I have been pleasantly surprised to find that the local MB dealer is willing to price match. If I need to replace my alternator I will check in with them, but I don’t plan to just hand over my wallet.
I have appreciated your insights. It is nice to know that I am not the only one who thinks it’s better to make an occasional costly repair on a car you like as an alternative to being perpetually saddled with car payments.
Last edited by KevinH2000; Jul 4, 2020 at 11:41 AM.




I am probably being punished by the car-repair spirits for not following Russell’s suggestions, because the new alternator didn’t work. I am showing about 12.3 volts at the alternator with the car running. The alternator warning message shows on the dash and the voltage reading on in the center fluctuates between 11.9 and 12 volts.
I suppose that there is a small probability that the new alternator has a manufacturing defect. I plan to take it off tomorrow or Thursday and then follow Russell’s advice and install the old alternator with the original voltage regulator. I may also have the new alternator tested, but it may be awkward taking a brand new alternator to Advance Auto since I didn’t buy it from them.
If that does fix the problem I may have to turn to my independent mechanic for help.
The Best of Mercedes & AMG
It sounds like one of the old alternators has a short between the stator and the case. That would cause a short on the alternator output lug.
So, that would blow the fuse in the battery cable.
Btw, if there is a short in the alternator stator, and that battery cable fuse wasn't there, it's likely that the battery would've exploded, spewing acid all over the place. Along with a high chance of a battery fire, and flaming pieces also spewing all over the place.
Yikes!
Most of Ford's charging systems didn't have fuses before ~2000. Ford "depended on" a barely-sized cable, connectors, and crimps.
For people, like me, that upgraded their charging system, not putting a fuse in-line with an upgraded battery wire, would be like playing Russian Roulette.
Google "car battery exploded", etc.
https://www.salvobrothersauto.com/ca...plode/1/8/2017
Also,
How to Avoid Battery Explosions (Yes, They Really Happen)
https://www.latimes.com/archives/la-...902-story.html
Good luck.
Last edited by RedGray; Jul 8, 2020 at 04:12 AM.




The alternator cable is definitely receiving power. The LED in my test probe glows red when I touch the post on the alternator. It was not receiving power before I changed the cable.
Before I replaced the cable, I had considered bypassing the fusible link and reusing the old cable. I'm glad I used good judgment (for once) and avoided that potential disaster.
Thanks for your response.
no use fitting your original back if the new one does not charge either!
12.5v at the main terminal of alternator that's perfect. ( But it MUST be check with the cable bolted to the alternator)
try this..
Unplug the small plug (data line) and leave it off.
start the car and wait about 30 sec then check output at alternator positive with a multimeter
forget about those ****ty probes for testing!
Also check for voltage drop!
pos lead of multimer on alternator positive and negative lead of multimeter on battery Positive post.
voltage should be close to 0v
Do the same for ground circuit
Positive lead on alternator casing and negative lead on battery negative post. Also 0v
All tests done with engine running!
Post results.
Good luck.
no use fitting your original back if the new one does not charge either!
12.5v at the main terminal of alternator that's perfect. ( But it MUST be check with the cable bolted to the alternator)
try this..
Unplug the small plug (data line) and leave it off.
start the car and wait about 30 sec then check output at alternator positive with a multimeter
forget about those ****ty probes for testing!
Also check for voltage drop!
pos lead of multimer on alternator positive and negative lead of multimeter on battery Positive post.
voltage should be close to 0v
Do the same for ground circuit
Positive lead on alternator casing and negative lead on battery negative post. Also 0v
All tests done with engine running!
Post results.
Good luck.




Check output at alternator positive with a multimeter - 12.2 volts - value on center screen of dash was 12.0
Also check for voltage drop! - No change between start and end of test - about 5 minutes total time
Pos lead of multimer on alternator positive and negative lead of multimeter on battery Positive post.
voltage should be close to 0v - It was 0 or 0.01V over the course of several trials
Do the same for ground circuit
Positive lead on alternator casing and negative lead on battery negative post. - Also 0 or 0.01V over several trials
All tests done with engine running! Test performed with engine running and data cable disconnected
Post results. - See above
Good luck. - I could use some right now
1. Do you think it is possible that my new alternator is defective?
2. I found another alternator shop near where I work. I called them late in the afternoon and the alternator technician had already left for the day. The person who answered the phone said he thought they "might" rebuild Bosch alternators. Do you think it is worthwhile to bring the old alternator with both the old and new voltage regulators by the shop and see whether he can rebuild it and confirm that it's good? At a minimum, this would permit me to (1) Confirm that I have a good alternator and (2) Return the new alternator to Amazon for a refund.
3. Do you think it is possible that I damaged the ECU? I found some on-line repair centers (one is actually 20 miles from where my daughter lives). The rebuild cost is approximately $600. This is not a sum that I would like to spend unless I'm sure that is the problem.
Thanks again for your response.
belt on? Cos bloody hell there is nothing else that can cause it not to charge.
new bosch alternator being defective! Highly unlikey. Not impossible of course. I suggest you have the new alternator tested on the bench for output. ECU is not needed to make it charge seeing the data line plug is off. So dont even go that route.




I considered whether I might have installed the alternator in the wrong orientation. I thought it may be possible to inadvertently install it upside down. However, the 6:00 minute to 8:00 minute segment of this video:
I brought the original alternator to an alternator repair shop near my work. (You may recall that I had taken it to another shop which said they did not rebuild Bosch alternators because they could not get parts.) The technician at today's shop said he thought he could do the work. I should know tomorrow whether he can. There are three possible outcomes of the rebuild process:
1. If the alternator works after I install the rebuilt unit, that is obviously good news and my problem is solved.
2. If the alternator doesn't work I will have additional information. My thought process is that if the rebuilt alternator doesn't work I will be able to eliminate the alternator from the list of possible sources of the problem. (I don't know what the other causes could possibly be.)
3. The technician cannot rebuild the alternator and I am in the same position as before I attempted the rebuild.
If the rebuild isn't possible or doesn't work, I am likely to take the car to my mechanic next week.
I understand that it has to be a rare event for a new Bosch alternator to fail. I could not see any damage to the alternator or the box it came in, so I'm not optimistic at this time that is the issue. But, as Sherlock Holmes and Mr. Spock say,
Last edited by KevinH2000; Jul 9, 2020 at 10:17 PM.
seeing you have a new alternator fitted and you have fixed the power supply yet you still dont have output.
I am thinking that the rubber coupling between the crank pulley and outer pulley part has come loose. It is possible that the crank pulley is slipping and not driving the alternator with enough rpm to start the charge process. Maybe paint a line from the top of the pulley down to the centre and then start the car then turn it off to check if the paint Marks havent shifted




I had to leave town on Saturday to help one of my brothers and I didn’t have time to work on the car today. I will try your suggestion one night this week.
I was able to pick up my original alternator from the shop on Friday. The technician installed the new voltage regulator (I had installed it previously, but I cannot be sure I did it correctly.). He tested it and as this photo shows the alternator is producing 14 volts.
I may put the original alternator back on the car after I check the crank pulley. That would eliminate the very remote possibility that the new alternator is defective.




Before running car
And After
After running car
Here's a video of the alternator with the motor running:
Here's a video of the view from the driver's seat.
If I rev the engine, the voltage will rise to 14, but the alternator-battery warning light illuminates. I cannot recall precisely, but fefore I had my current problem, the voltage would read in the 13.4-13.8 range at idle without revving the engine.
I hope that this suggests another possible cause of my problem. I'm wondering whether it is worth an hour of my time to swap in the original alternator to see if that makes a difference. It is possible that the new Bosch alternator is not the correct one for my car or has a defect? It appears identical to the original and it is the correct part number (AL0810N) according to the web sites I checked.
Last edited by KevinH2000; Jul 14, 2020 at 07:38 PM.




According to information I found on another website the next options for troubleshooting Fault Code 2062 [2] - Alternator Serial Interface: No Connection to Control Module N3/10 (ME-SFI Control Module) are:
- Check electrical line between component N3/10 (ME-SFI control module) and component Generator for contact and routing and (or) line breaks.
- Check alternator regulator with oscilloscope.
I hope that Red Gray or Russell will let me know what they think and how I might check the electrical line. Most of the line is not easily accessible and I want to avoid creating another problem. I am also planning to swap in the original alternator. If the original alternator works as well as the replacement, I might as well return the replacement for a refund.


