Odd Electrical Problem
 

Hi All, Car is a 2009 L, 135K miles. Have a few issues over my 2 year ownership, nothing major. Yesterday while driving I all of a sudden get the warning "check brake system immediately" followed by "SRS malfunction" and then the radio had no volume. Cruise didn't work either. I was in downtown Boston and had an hour+ ride to home. Brakes seemed fine and the lights would go out and come back on intermittently. Shut car off, radio came back, no lights etc. Then it would all start again. Came home, scanned it and had a few codes relating to ABS/VRCS and power steering. Cleared everything and was fine for a few miles, then came back again. I also thought of battery right away. Battery is fairly new and alternator is charging as it should. All voltages were in spec. I found this thread
https://www.clublexus.com/forums/ls-...ke-system.html
referencing the power supply to the electronic EM brake, etc that is in the trunk. I do have the C1377 code which references a capacitor issue. Found a different module on the big auction site and will arrive this week. Looks like a plug and play. Just weird that it just happened out of the blue and trying to figure out if the radio problem is associated or separate. I did check the 2 areas in the back that have been known to collect water, one on each side of car and they are both dry and no issues there. I get no radio codes or amp issues coming up either. I checked the whole engine compartment for animal intrusion, don't see anything. Would love to hear others experiences. Thoughts?

Once you've got the replacement module properly installed, you'll see if the old one was was the entire issue. Any electrical issue is a challenge, make it computerized and it gets even harder. Sounds like you're on the right track.

Honestly I think that's a ghost code. I'd be checking bus diagrams and scoping CAN to see if there's any intermittent problems with comms.
Radio acting up kind of points towards that. Any jobs done on the car recently? Anything that could affect wiring? Is your interior dry?

I hope so!! Will update this thread when I get to that step!

I was wondering about the "ghost code" theory as well. Hence clearing all yesterday and then re scanning today. The 1377 came back. Your theory of bus/CAN is valid and I will see what I have to do to do that.
I considered any recent work as well. The only thing that has been done recently is I replaced both rear air shocks. And that was probably 3 weeks ago. Interior doesn't show any signs of water intrusion. I might pull some carpets and check. Also, this scan doesn't say anything about the "SRS/Air bag" warning that was also coming. And no radio/com codes. Also, was not getting any EM brake or ABS warnings on the dash. Would think it would have thrown the VSC warning light. Very strange.
I have dealt with BMW's for quite a while and this is all earily similar! Which is why I went Lexus to avoid this stuff! Thanks for the advice.
https://cimg0.ibsrv.net/gimg/www.clu...4d2272f3ae.jpg
Here is the scan from this morning. You will see "History" and "current".

Hmm. Rear shocks. Back seat and trunk areas got plenty of MOST bus wires (radio<->amp) and also wiring to abs capacitor unit. Try retracing your steps?
Also, check areas where roof drain hoses go thru - behind driver's and pass' kickpanels.

Checked with FSM, C1377 sets when IG voltage drops below 9.5v. I call it a ghost.
Check trunk side 'pockets' (left is abs capacitor and parking brake units, right is amp).

Boykie, can you tell me what FSM is?
I did check those pockets looking for moisture, everything was bone dry. And we have had quite a bit of rain lately. Any suggestions on checking CAN comms? I don't have tech stream. Do I need a scope? Thanks

Is your scanner a high end unit that will read the codes mentioned? I'm no expert in this area. So nice to see a capable DIY member willing to deep dive.

Factory Service Manual

Had to drive the car for a short distance today and now I have the following. This is in addition to the other issues from saturday/sunday. I did not have time to scan it today. Hoping this is all pointing in a direction. Thinking I want to monitor "live" info for alternator voltage/operation.
Check VSC
Check Electronic parking brake
Check ABS.
Still have the Check brake system and SRS/airbag .
Today radio was on. Radio went off after 5 min of driving and then a few seconds later the Christmas tree of warning lights and dash warnings started happening. Tried to set the cruise and the light in cluster would just flash. Car drove fine. I HATE electrical issues!! Will scan tomorrow and see if there is anything different than Sunday scan that I posted above.

Looks like you're not charging. Radio turns off when batt voltage drops below certain threshold. Alternator and/or battery suspected. Instead of over-relying on that chi...ASIAN (colonel, ha kol beseder? ken? lol) scantool just do a multimeter voltage check at battery terminals and see if it falls or rises just sitting running.

Boykie, I was waiting for you to comment on the scanner!!! It actually isn't too bad for shade tree. We are on same page I think regarding the charging system. I did hook up a meter on Sunday and watched it idling. Was in the 13.7-14.2 range for 5-10 min. I am wondering under a load if that makes it bump. But I am going to set it on a graph and look for spikes or drastic drops while driving. Battery light has not gone on once though, which I find odd. Maybe that pops with a complete failure. Yes, the warning light does come on pre start. Will start looking at Denso alternators tonight. Fingers crossed it is that simple. Thanks for taking the time to respond.

I'm ok with multiple launch clones, and e.g. thinktool still uses that, but I do find it rather confusing at times and not as able as TS with LS. As a multibrander - xtool are as good and as bad as any of those launch clones.

I think it’s possible that a defective battery is causing your problem. Replacing the battery is easy and relatively inexpensive. Doing that would not be the wrong thing to do.