Hi all,

Long time lurker, but I made an account to post this, as I'm a bit stumped on what's going on. Here's some background and then the issue:

2014 GS 350 AWD

BACKGROUND:

• Two weeks ago, popped my tire and put the spare on. Immediately drove and got four brand new tires. Sidenote to this-- until the new tires were installed, I would almost always have a TPS warning light on (like the warning for a flat tire) that would intermittently come off and on seemingly at random , and my tire psi display would never work, just showing "--" for each tire. Adding this detail because I think it shows they hooked the new tires up properly.
• Parked car over my weekend (Tues-Wed) and didn't drive it. Over this weekend, I installed a car seat for my child (driver's side rear).

MAIN ISSUE / CODES:

On Thursday (My "monday") I started the car and was met with this:

Some things to note-- Door ajar light, seatbelt light, and headlamp light are not part of the issue. They're only on because those conditions were actually met. Additionally, the "AFS OFF" light is not solid, but blinking.

The car's notification system was posting the following messages:

• Check SRS Airbag System
• Check ABS
• Check BSM System
• Check AFS

When I ran a diagnostic with my OBD2 Scanner, I was met with the following 18 codes (document attached):

• C1296: ABS Control System Malfunction
• B1613: Front Airbag Sensor Initialization Error (RH)
• C1582: No description available, but falls under "Electric Motor Power Steering Code"
• C1241: Low or High Power Supply Voltage
• C1405: Open or Short in Front Speed Sensor RH Circuit
• B14C2: Rear Right Seat Heat Sensor Circuit
• B14C3: Rear Left Sear Heat Sensor Circuit
• B1585: USB Device Malfunction
• C1783: No description available, but falls under "Air Suspension Code"
• U0122: Lost Communication With Vehicle Dynamics Control Module
• U0124: Lost Communication With Lateral Acceleration Sensor Module
• U0126: Lost Communication With Steering Angle Sensor Module
• C1A45: Vehicle Speed Sensor (under "Blind Spot Monitor Master Code")
• C1A45: Vehicle Speed Sensor (under "Blind Spot Monitor Slave Code")
• B2415: Vehicle Speed Sensor (under "HL AutoLeveling Code")
• C2122: Transmitter ID 2 not Received (Main)
• C2123: Transmitter ID 3 not Received (Main)
• B2610: Tilt Position Sensor or Tilt Motor

That's quite a few codes. The most I've ever seen. In doing some research, I've learned that some of them are "sympathetic", and having one of them will trigger the other. I haven't done much to try and fix it, as I've been busy with work. I've also read that someone had a similar issue when they needed to change their keyfob battery, but mine seems to work fine...

I've disconnected the battery, and reconnected it, hoping it'd be an easy fix, but that didn't change anything.

I have to imagine it's (hopefully) an easy electrical issue, since it was seemingly so sudden.

Does anyone have any thoughts on what might cause this? Other than my steering feeling a tiny bit looser (could be placebo), and my blind spot monitor not working, the car runs mechanically just fine. Not sure at all what this could be. Maybe a delayed response to the spare being put on and the tires changed?

I'd greatly appreciate any and all advice or possible solutions. If you have any questions, please ask, I'll get back as soon as I can. Thank you!

 

@twistedfish - How new and sound (i.e. health) is the battery? Can you start the engine? Does your key fob work (to lock/unlock doors and trunk)?

Your problem sounds like what can happen when the battery has very low amperage capacity remaining (e.g. bad cell or almost drained) yet the battery still can measure about 12 volts and is still able to light up the instrument lights/messages and log DTC codes - and such a deeply drained battery condition can even remain capable enough to even start the engine.

Under normal conditions if a child's car seat is put in a seat and the seat belt is permanently connected, that seat belt being connected actually prevents the Network Gateway ECU in the vehicle from going into 'sleep mode' when the car is turned off. Without the Network Gateway ECU being able to go into 'sleep mode' there is a continuous drain on the battery with about a 25 mA (0.025 Amps) or greater constant amperage draw. What I do not know is if this condition applies only to the front seat belts being connected or if it applies to both front and rear seat belts in the Lexus GS 350. Without knowing if connecting the rear seat belts causes a continuous drain - this may not be the root cause of all those DTC codes you retrieved - - but a lot of the codes do indeed specify things like Low Power Supply (battery) Voltage, Seat Heat Sensor Circuits, etc. that are either directly or indirectly associated with this seat belt occurrence.

If ('if') the child's car seat and the seat's associated seat belt is actually causing your problem - parking the car for two or three days without driving it is more than enough time to really drain the battery down and possibly throw codes and messages. And, when features and options on the car are activated or powered-up, the more messages and codes are likely thrown. That said, if the child's car seat was put in after the car was parked for two or three days - it still only takes a couple days to drain even an almost new, fully charged battery...

Keep in mind that the 'Check SRS Airbag System' is directly related to seat belts. So, another question to consider - beyond permanently connecting the seat belt on a child seat - is if you might have mistakenly disconnected a Molex plug (that is part of the seat belt/ airbag system) behind/below a seat while feeling (searching) for the child seat restraining anchor latch system loops behind the seat. I suggest you might want to ponder that question...

I would: Disconnect the seat belt on the child's seat - Disconnect the car's battery - Fully charge the battery - Reconnect the battery - Delete the DTC codes - - See if that takes care of things!

Let us know the outcome, please...

 

@twistedfish - Besides the information in my reply post above to your thread - two other things come to mind you might want to consider and eliminate as a possibility that caused one or more of the 'Check' messages.

The sensors in the front and rear bumper are intrinsically connected with the Airbag System. So, (for example) if you were to nudge even a cardboard box with the front or rear bumper while parking in a garage for instance, it might trigger the 'Check Airbag System' message. Another thing to consider is a seat's seatbelt pre-tensioners and its related clock spring is likely to also trigger the 'Check Airbag System' message if the seat belt has been rearranged or revamped somehow to accommodate/secure a child seat into position.
It seems the root cause of your problem might be concentrated quite distinctly on what took place to install the child seat in your GS 350.

Let us know the outcome, please...

 

@twistedfish - Evidently you only wanted to make one post asking for help and then go hide!

 

Hi! Sorry for the late reply, I've had quite a busy week! I really appreciate your post, it's very in depth. I think you're likely right that the carseat is the crux of the issue. I plan on taking the car to get the battery checked out at autozone, since I have no way of checking the battery health or getting it charged otherwise.

I have a jump starter battery that I tried hooking it up to, but I don't think it's the right tool for the job. I tried using it to charge the battery, but all it did was "click", I believe because it's not desinged to fully recharge the battery, but to give it enough to start a dead one. Interestingly still, I cannot detect any signs of a low battery (car starts right up first try, no dimmed lights, etc.) though I still think your analysis is correct.

Additionally, I tried to wrangle around the seat and see if anything was blatantly disconnected under the seat where the carseat was installed, but couldn't find anything disconnected. Even so, I attempted to leave the battery disconnected for about an hour (to hopefully reset the ECU) and even cleared the codes with my OBD2 scanner, but upon start up, they (the codes, lights, warnings) were all still there. Definitely frustrating.

Like I mentioned, I plan to take it to autozone to get the battery tested today, and will report back what I find. However, I'm a bit confused that the alternator wouldn't just charge the battery back to where it needs to be if I leave the car running for a while?

Very interested to hear your thoughts, you seem incredibly knowledgeable. Again I apologize for the delayed response, but I should have more free time to reply for the next few days. Thank you so much!

 

Hi, just checking in and updating— I hope this reply finds you well!

Currently, the car still has the same issues. I went to get my battery tested, and the guy said something about an alternator voltage error, saying that it wasn’t a consistent number, and in his words (from AutoZone) that I probably need a new alternator. I hope this is not the case. I’ve pulled the back seat cushions and tried to find any unplugged molex cables, but haven’t been able to. I’ve pulled almost all of the fuses under the hood and didn’t find anything broken. I’m at a loss here, man, it’s definitely a bizarre issue. I’m with you on your analysis though, I bet it has something to do with the car seat/ battery. Maybe I should just buy a new battery and see if it works? The guy at autozone said the battery was fine, but idk.

any help is much appreciated. Also in case I don’t reply immediately, my wife and I just welcomed our first born into the world last week! Anyways, thanks again in advance!