Started with intermittent power on/off for music. Had to manually turn power back on to the radio. Then, would completely lose power to the head unit and it would cycle back on automatically. Then, would lose power to the head unit and mirror N/S/E/W indicator and it would cycle back on. Now I am losing all power (head unit, mirror, tach/speedo, power steering) for a split second (enough to make my steering wheel try to jerk back to center due to lose of power steering?). Car does not lose power and engine remains on. Warning lights on dash come on (CEL, TCS, small red triangle with ! mark and I think a red arrow encircling the triangle (maybe power steering)).

Seems like a fuse or relay that all of these systems share. Recently had a P0101 CEL pulled for MAF. Went away on its own. I have not done any diagnostics on the car yet. Just got off work and tired.

Any help would be greatly appreciated. Thanks in advance.

 

Start with a full test on the battery under load. If the battery checks out, then look at the alternator output to see how clean it is. You can do this with any decent multimeter by measuring the AC voltage across the battery. It should be tiny. If it isn't tiny, there's a problem with the alternator. It sounds a lot like a sulfated battery, but doesn't have to be.

 

Long story short.....Car was at body shop for work and battery discharged below 10 volts so they swapped in a new one. Had the car back for 3 days until it quit working. Dealership diagnosed a bad fuel pressure sensor. While they had the car they said battery was bad again so they swapped in a new one. I swapped out the fuel pressure switch on my own and also resealed the valley plate and changed out all spark plugs while I was under there. Car still doesn't start.

New symptoms:

Dash bezel doesn't light up (no tach, speedo, other lights that normally come on) in accessory mode or when pressing brake and attempting to start car.
All blinkers work, headlights and high beams work and indicate on bezel, open door indicators work.
Security light continues to blink with car unlocked (this isn't really new, but forgot to mention in op).
Front passenger window does not work (at driver's side master switch and at the door switch) - all other work.
Radiator fan turns on. Car does not attempt to turn over. No starter engagement.

Going to groom all the fuses in the morning, but wanted to start here. Battery was removed during all the work. Triple checked all electrical connectors went back in place (had pictures from fuel sensor safety recall).

This sounds like it's going to get really expensive to fix. Any help is highly appreciated as always.

 

Could this be the case? https://www.clublexus.com/forums/is-...t-start-4.html
Key fob still does all of the things, but could the Immobilizer/certification ECU have gone bad? Not sure how to account for the dash lights not working.

I'm guessing there's no real way to figure this out without getting it hooked up to Techstream at the dealer. Haven't gotten around to checking fuses and voltages.

I'll try to keep this updated in case someone can chime in. Thanks all.

 

Yeah, that's what I was thinking when this popped up. Not the first time for this either. Other members have had the same problem with the same insane repair bill for something that should never happen. This another piece in the puzzle of why I got the LiFePo4 batteries. The BMS disconnects power when the voltage drops below 9.6v. Lead/acid can't do this because it doesn't have any means of determining when the voltage drops too low. Sorry to say, you'll likely have to spend some significant cash to get running again.