Alternator Question (yes I searched)

[chitownV]

It’s okay if you don’t have hands on experience with the 3.2., it really is. You mentioned looking mechanically and it was not clear what for, especially in the 3.2. We can all learn something new, including you @ggleavitt, and that’s a good thing.

Nice of you to copy & paste VIDA, but it might not be enough in how to approach this in the real world based on 3.2 owners’ common experiences. Google and YouTube can help with the listed items I mentioned.

Some of the first lessons learned in automotive tech school is to interpret diagnostic trouble codes as well as hands on training, as it’s majority of the program. That’s also why we go to shops with hands on experience with Volvos. It’s also the reason to double check work. I’ve fixed more problems/repairs on other Volvo XC90s completed by non-Volvo shops than I’ve done work on my own XC90. 3.2 owners of past have done a great job of sharing their hands on experiences, which helps other 3.2 owners…even better when they make videos.

Well, let’s see what @mikieboy will do.

[mikieboy]

Thank you for the all the thoughts I really appreciate it. I dont have VIDA yet my dice is coming from China. On my obd2 scanner I also got the U0120 code and I think oxygen sensor code. I am not sure if any have a connection. The alternator looks like good from what I can tell the coupler looks good as well. I really would like to fix the power service urgent message. THinking out loud maybe its a ground issue? If the alternator is fine what could cause the error?

[chitownV]

Have you cleared the code to see if it comes back? What was the code before the alternator change? If the code is the same as before, you may want to look into physical issues related or around the alternator (wiring/connector, decoupler, gear/pulley bolts).

The O2 sensor (not sure which codes) should be independent, unless you have an ECM issue, but you sent that in to XeMODeX.

The saying, Keep It Simple St*pid (KISS) first and double check the shop’s work. Disconnect the battery, then reach in to unclip the signal connector if you can reach it. Use contact cleaner and maybe you can reach a phone in there to check/take pics if any pins are bent and if the wiring looks good. Reconnect.

Unfortunately, if you cannot get a good view and check the connector, then removing the intake manifold and double checking the entire job might be prudent. This will also give you better access to the wiring and double checking the other parts & common issues. Sometimes you just have to get your hands dirty or pay someone else who knows Volvos to do it.

No need to read VIDA how charging works as you are getting the normal 13.5V, one of your original concerns. Here’s a video on the connector, ~0:52 time. It also shows the decoupler work later in the video. Edit: careful of live power, thus disconnect battery, good to repeat.


Sometimes if there is an issue, like the voltage has a discrepancy with a signal (and other inputs like rpm), then it may throw alternator codes. Blips in signals or voltage could throw codes. Blips might not show up in OBD2 live readings due to the lag or refresh rate of the scanner. Here is a video showing the gear/pulley bolt which I am assuming the shop did not touch or know to look at (same item before & after the alternator replacement).



There are a lot of detailed videos from 3.2 owners and they can be more valuable than reading VIDA documents, especially in learning common issues and how to diagnose.

Good luck with your journey and keep us updated.

[mikieboy]

UPDATE... I hate when I dont read updates so here is mine... I took my xc90 to the dealer they immediately said alternator, I asked are you sure did you double check the one I just put on and they said. I put a brand new bosch 180 on. Well $1300 later I still have the power service urgent so they come back and say that they found a short in the ecm ( they want 3k) to replace. Xemodex said it tested fine. I have checked the wire for continuity and it seems good as well, so now I am back to the ecm. Thinking about getting another ecm and either sending it back to xemodex (not sure since they already said it was fine) or going with another shop I found on the internet out of California. I will update again when I get anything new.

[chitownV]

Hmm. I’ve heard a couple time Xemodex and that other place you are talking about can miss a small solder crack or similar. It happens. Are you going to send both the ECMs so they can transfer the software over?

Edit: also, did they check the drive gear bolt?

[ggleavitt]

So in the end you have an externally (LIN bus) regulated alternator with no regulation, good to know. No voltage whatsoever on that pin? If you have voltage, anyone put a scope to see the waveform?

And sure there are no alternator specific codes are being reported by the vehicle? As was suggested earlier, I don't "know" the 3.2 (sorry!) but this is a Denso ECM and certainly has similar error reporting criteria to that of my two V8s. What I'm not certain of is whether the ACM/ECM bus connectivity will be bi-directional with a request/response for a trigger or if it's inferred (ECM directs an output to ACM over LIN, no change in voltage sensed by ECM) but maybe that's getting in too deep. Nevertheless, if you have a non-functional ECM/ACM connection the vehicle should be reporting something. When you performed the continuity check, you did it at the connector interface, yeah?

I'll be very interested to see exactly what your root cause was (is) and thanks very much for the update.

edit- add scope/waveform

[chitownV]

@mikieboy it might be time to figure out VIDA for yourself or time to get your hands dirty (like in the videos) to double check the work. I’ve fixed numerous dealership jobs because they didn’t want to spend the time.

Older vehicles require more historic knowledge or more time in diagnosis as anything can happen (weird things from drying out & cracking of wire insulation, a past rodent issue, to bad previous work that damaged other parts).

Did the dealership print out, or put on the work order, the specific codes and readings? Just throwing it out there, what if you have a loose negative battery cable. It’s little things like this that should be verified they are tight and good through the diagnosis process. What if your original alternator went bad and damaged the battery somehow, but the new alternators are still putting out the correct voltage. I’ve seen bad battery plates cause weird issues and the dealership might not spend the time to properly go through the diagnosis process, especially for something that appears electrical.

If you can share some more info, that would be helpful. Like, all the checks the dealership tech did and if it’s on the repair order.

I would still double check all the mechanical, it’s just too easy to overlook.
Here is one link explaining how the mechanicals can cause your codes based on a potential code @ggleavitt posted. Look at the possible causes, all mechanical: https://www.dtcdecode.com/Volvo/ECM-P062074

Also, since you are new to the 3.2, it’s good to read on what you should expect and the scheduled maintenance. Save money and avoid the dealership, you can do a lot of the work yourself. If you are not handy, then this will help to be more well informed the next time you go to a shop.
Welcome to the XC90 3.2 community. Post #7
https://www.swedespeed.com/threads/the- ... st-7332383

[mikieboy]

Just to answer a few of the questions. Yes bolt is new and so is battery. I was hoping I would get more information from dealer, they gave me lots of other things I should have done (which I know I need to do) for instance changing a fog light bulb. I agree that dealerships just want to push you in and out and take all your money and dont want to trouble shoot, doubt any of them know how to use an oscilloscope. I have double checked all main cables and grounding points on the car (not saying I got them all but I tried) I have even checked the CEM mine was clean and water tight still which was nice. I wasnt impressed by the dealer (in atlanta) seemed like they just wanted to throw parts and money. I also had to wait 7 hours not a fun Friday.

[chitownV]

What are the actual codes and how did you check?