V8 Alternator

Post by **Roger_850T** » 19 Jun 2021, 10:24

My turn for the Alternator Failure on the 2005 XC90 V8 (170k miles). Yesterday the wife got the "POWER SYSTEM SERVICE URGENT" message, with the accompanying red triangle, power steering weakness, radio off, and potential brake issues. She parked the car and took a Lyft home.

Several hours later, I go to the car, laptop and DiCE in hand, to evaluate. I found:

Battery voltage 12.9V (excellent)

Aux belt fully intact

Started Car:

Got a warning about power system service needed, not urgent, orange triangle (not red). Acknowledging the message turned it off for now.

Voltage went up to 14.0V then tapered as it should

Found Multiple codes:
12:31:58pm ECM-P062001 Generator Control Circuit - General electrical failure
12:31:58pm ECM-P062074 Generator Control Circuit - Mechanical Failures - Actuator Slipping
12:33:23pm ECM-U012900 Lost Communication with Brake System Control Module
12:33:23pm BCM-C008216 Brake System Malfunction Indicator - General Electrical Failures - Circuit voltage below threshold
12:33:25pm TCM-056200 System Voltage Low

After another hour or two, I drove it 13 miles to home, with no issues.

Looking at the codes, the generator had issues first, and after another 80-85 seconds, the rest follow, and it appears likely they are resultant of the generator issue.

ViDA reports that the two generator failures have:
25 Operation Cycles since fault was first found
9 Confirmed Operation Cycles with active fault
It was first found on 6/16/21, at 12:31pm, which would be about 2 days before the above shutdown on my wife. Thus, it's happened in 9 of the past 25 cycles, and only the last one set a trouble code that caused the red triangle warning.

ECM-P062001

The engine control module (ECM) regulates the alternator charge voltage (via LIN communication) on request of the central electronic module (CEM) (via CAN communication). The alternator control module (ACM) sends information on the fault to the engine control module (ECM) (via LIN communication). The diagnostic trouble code is generated if the alternator control module (ACM) sends the engine control module (ECM) information on an electrical fault in the alternator.
The diagnostic trouble code can be diagnosed when the engine is running.

ECM-P062074

The engine control module (ECM) regulates the alternator charge voltage (via LIN communication) on request of the central electronic module (CEM) (via CAN communication). The alternator control module (ACM) sends information on the fault to the engine control module (ECM) (via LIN communication). The diagnostic trouble code is generated if the alternator control module (ACM) sends the engine control module (ECM) information on a mechanical fault in the alternator (engine speed exceeds a certain value but the alternator is not operating).
The diagnostic trouble code can be diagnosed when the engine is running.

The Alternator Control Module (ACM) is internal to the alternator, what we would generally refer to as the voltage regulator, except that instead of receiving an excitation voltage, it is communicating via serial communication to the ECM via LIN (Local Interface Network, 9600 baud), and the ECM is communicating to the CEM via the CAN network.

So it sounds like the codes originate in the ACM, and are set when the engine is turning fast enough to charge, but the alternator isn't charging. In this case it sent out both a General Fault and suggestion of a mechanical fault.

While one answer is the apparently obvious "it's time to replace the alternator", I am trying to figure out more about the actual failure here. Here are some more notes:

I know I have an oil leak in that vicinity, (have been trying to find it, not successful yet,) so I expect to find the alternator covered in oil.

Valve Cover gaskets and timing cover gaskets were done ~28k miles and just over 2 years ago, when I did the balance shaft bearing.

Battery is 7 years and 90k miles old. However in Maryland we no longer have the temperature extremes we did in Chicago, and it's been performing flawlessly to date, as indicated by the solid resting voltage and no issues cranking the engine over.

I am wondering if it is something like oil causing an electrical issue on the signal line from the ECM, and perhaps I can just clean that connection well and have an expectation of reliability. (Of course it will come back if I don't fix the oil leak, but it will buy me a few months to resolve that.) Or is there an intermittent failure within the alternator, and the only fix is to just replace the whole thing.

Any thoughts? Thanks in advance for any input!

Roger

Post by **ggleavitt** » 19 Jun 2021, 12:18

Had one of these come up in the Sport last November. Drove it home and replaced the alternator with a genuine Bosch AL0821X reman, never seen a message since. No oil per se on mine, just got worn out I think.

No freewheel pulley on this alternator but I think your assessment of the error is correct. Alternator turns but does not adequately charge.

New style alternators if dealer replaces have the snorkel cooling vent on them (see link- https://goo.gl/photos/sgUfDcBgnQY7ETK58 ,photos do not include the heat resistant wrap over the duct). I've never seen one "live" in an XC90 before but that's what I'm told gets put in. I was never able to get my "revised" ducted reman alternator installed doing it from the garage floor so I ended up putting the old cover back on. I'm told it's possible.

Could try cleaning the connectors but if it's the original 2005 alternator, it probably needs replaced. I would see where the oil in the back is coming from though for sure.

Post by **Roger_850T** » 19 Jun 2021, 14:51

ggleavitt wrote: ↑19 Jun 2021, 12:18 New style alternators if dealer replaces have the snorkel cooling vent on them (see link- https://goo.gl/photos/sgUfDcBgnQY7ETK58 ,photos do not include the heat resistant wrap over the duct). I've never seen one "live" in an XC90 before but that's what I'm told gets put in. I was never able to get my "revised" ducted reman alternator installed doing it from the garage floor so I ended up putting the old cover back on. I'm told it's possible.

I see list price on the new duct is $188, almost as much as the reman alternator. Based on that and your experience, I think I'll just go back with the existing duct.

ggleavitt wrote: ↑19 Jun 2021, 12:18 Could try cleaning the connectors but if it's the original 2005 alternator, it probably needs replaced. I would see where the oil in the back is coming from though for sure.

I think that's where I'm at, just replace it. I'll hopefully get it out today and tomorrow, and then order a new one Sunday night, probably with a new serpentine belt and anything else I find I need. FCP shows them in stock, so it will ship out Monday and I'll get it soon after that. Back on the road in no time!

Roger

Post by **ggleavitt** » 20 Jun 2021, 10:03

You figure it lasted for as long as it did without the snorkel, it can last the same again. I bought a snorkeled used alternator right after the purchase of the first V8 in 2015, assuming it was important. I think in retrospect it's nice to have but not a mandatory.

Curious to know how long it will take for you to do the removal and replacement, could you post with some hours once you're finished?

Thanks

Post by **Roger_850T** » 26 Jun 2021, 23:03

It's done, and it's working so we are happy.

All in, it took 10-11 hours. It should have been a few hours less.

Taking it out was 4 hours the first day, and about an hour the second. The first day I got everything moved except the alternator - jacked the car up, disassembled the strut, disassembled the tie rod end, removed the axle. This took twice as long as it should have, as it was very hot/humid, and I had to stop a lot to wipe the sweat off my glasses and stay hydrated. The last person to connect the tie rod end to the steering knuckle used 'way too many ugga-dugga's, and it took a lot for me to get it off. I got stuck on the alternator - there was a cap on the B+ line and I wasn't sure how it should come off. I stopped working, and asked, learning that it just pulls right off. The next day, it took about an hour to remove B+, remove the field wire, and get the alternator out and on to the floor.

Putting it back was 6 hours, but that included a lot of cleaning (and looking for an oil leak,) plus a full check of the alignment (camber and toe-in) as I had disassembled the joint between the steering knuckle and the strut.

All in all, this was not the worst job I have done. It's tough, as there are a lot of things that have to be done with minimal clearance, and you have to pull out all your tricks to do things in weird places and angles. But I'm used to doing things without a lift, and there's always minimal clearances and weird angles when you are working on a car on jack stands. R/R the transmission, RWD or FWD, is worse.

Notes for the next person:

Drive shaft has to come out. Pick your favorite method to accomplish that - I disconnected the strut from the hub, and had plenty of clearance. The bracket that supports the driveshaft under the alternator also has to come out for clearance.

I didn't have too much trouble getting the axle out of the hub, but that's because I replaced the hub 2-3 years ago. At that time, it was a real bear, and took hard blows with a sledgehammer to get it to move. I probably destroyed the bearing then, but it was bad and coming out anyway, so it didn't matter.

I left the control arm and the ball joint attached. Brake disk and caliper stayed attached. Be careful not to stress the brake hose with the caliper and disk flopping around.

Disconnect the ABS sensor and move it out of the way.

I was able to do all 3 alternator-to-block bolts from underneath.

I did the battery cable from the top, using a 1/4" socket that was 14mm and had a universal joint built into the socket. The angle was really acute, almost 90° out to the side, but I was able to get it.

Be patient with re-installing the alternator bolts. It's really easy to cross-thread into the aluminum block. Don't force it. Once I got them lined up right, I was able to screw them all the way in with just my fingers, and didn't need a wrench until the last 1/4 turn. If it's not going in, it's not aligned right.

You have to remove the 10mm nut and bolt that hold the fuel lines in front of the alternator. Remove the nut/bolt, and move those lines right out of the way.

I saw one you-tube video where the guy dropped the sub-frame to get access. I thought about that, but didn't need to do so to get the access I needed.

I hope this helps!

Roger

Post by **ggleavitt** » 23 Aug 2021, 09:41

I've done two of these now, having replaced the alternator in the '06 Ocean Race (140k) over the weekend. This vehicle coded ECM P062001 (Generator Control Circuit/General Failure Information/General electrical failure, B8444S) and ECM P062074 (Generator Control Circuit/Mechanical Failures/Actuator slipping, B8444S) last week so was just a matter of time. I used genuine Bosch boxed AL0821X (OE reman) for the replacement(s).

The job recommendations are spot on in the previous post. One thing I did in addition was to disconnected the fuel lines at the top of the rear bank and in doing so got lots more room for the R&R. The lines are hard (pipes) where they snake around the front of the block and connect at the top of the back bank but where they enter the engine compartment it's a flex hose. If you pull the top connectors, you can swing the pipes all around the opening. I used a 5/16" disconnect tool.

For me one the hardest parts of the job is getting the B+ nut off the alternator. I've since resorted to an articulating "pass-through" socket and have loosened/tightened from the back side of the alternator (via the bottom) with decent success. See photo for what was used:

Some have noted that the B+ terminal nut changes size, might be old 13mm with new 12mm and the original plastic cap does not fit.

There's another thread on V8 alternators in Swedespeed for anyone interested- https://www.swedespeed.com/threads/v8-a ... ht.375921/

edit- correct some typos

Post by **ggleavitt** » 24 Aug 2021, 15:54

Lest I forget, both my alternators came with this notice:

My batteries are relatively new so I put a charger on them while doing the work. Battery gets re-connected with ignition in the POS II position and there are a couple calibrations you can do after the fact (interior cabin fan and sunroof plus lock/unlock the vehicle a few times). Instructions for those are are in VIDA.