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Taking in my 2016 GS 350 for second time to dealer find out why I keep blowing fuse which controls BSM, headlights - lost power windows, no high beams, malfunction lights on dash. Battery tested fine, bunch of fault codes like short to ground BSM.
Dealer replaced fuse and it was fine for a week but then Found the rain sensor loose and dangling around came off hooks and then 2 starts later the car went back fault mode. Windscreen is genuine, sensor gel pad looked like it was leaking or wet adhesive. Never touched this part before.
Could the loose rain sensor cause a short? Dealer seems unsure what the cause is. Any ideas?
Taking in my 2016 GS 350 for second time to dealer find out why I keep blowing fuse which controls BSM, headlights - lost power windows, no high beams, malfunction lights on dash. Battery tested fine, bunch of fault codes like short to ground BSM.
Dealer replaced fuse and it was fine for a week but then Found the rain sensor loose and dangling around came off hooks and then 2 starts later the car went back fault mode. Windscreen is genuine, sensor gel pad looked like it was leaking or wet adhesive. Never touched this part before.
Could the loose rain sensor cause a short? Dealer seems unsure what the cause is. Any ideas?
Is the rain sensor on the same circuit as the fuse blowing? I'll check my schematics if you don't know
Is the rain sensor on the same circuit as the fuse blowing? I'll check my schematics if you don't know
Good question - codes were U0182, lighting control module lost comm, U1110, U0142, C1ABE - I think the rain sensor also on same part as headlight sensor. I think it is a 10A fuse
The rain sensor is powered directly from the LH-IG fuse. Also fed from that fuse is the ignition circuit for these systems:It pretty much just tells all the ECUs and relays that the car is on and it can power up. Try disconnecting the map light assembly (as above) and leave it for a week. I'm not a mechanic but at work I trouble shoot electronics...start with the most obvious item.
With luck, the short will be repeatable on demand and that it's due to something moving....hopefully the rain sensor or something up in the map light.
Adaptive Front-Lighting System
Air Conditioner
Audio System
Automatic Glare-Resistant EC Mirror
Automatic Light Control
Combination Meter
Door Lock Control (LHD)
Door Lock Control (RHD)
Double Locking (LHD)
Double Locking (RHD)
Dynamic Radar Cruise Control (LHD)
Dynamic Radar Cruise Control (RHD)
Electric Tension Reducer
Engine Immobiliser System (LHD)
Engine Immobiliser System (RHD)
Entry & Start System (LHD)
Entry & Start System (RHD)
Front Fog Light
Front Window Deicer
Front Wiper and Washer
Fuel Lid Opener
Garage Door Opener
Headlight
Headlight Beam Level Control
Headlight Cleaner
Illumination (LHD)
Illumination (RHD)
Interior Light (LHD)
Interior Light (RHD)
Lane Keeping Assist (LHD)
Lane Keeping Assist (RHD)
LEXUS Navigation System
Light Auto Turn Off System
Light Reminder
Luggage Compartment Door Opener
Mirror Heater (LHD)
Mirror Heater (RHD)
Multi-Display
Multiplex Communication System (CAN RHD)
Parking Assist (Back Guide Monitor)
Parking Assist (LEXUS Parking Assist-Sensor)
Power Seat (LHD Driver's Seat 10-Way Seat Position)
Power Seat (LHD Driver's Seat 16-Way or 18-Way Seat Position)
Power Seat (LHD Front Passenger's Seat w/ Seat Position Memory)
Power Seat (RHD Driver's Seat 10-Way Seat Position)
Power Seat (RHD Driver's Seat 16-Way or 18-Way Seat Position)
Power Seat (RHD Front Passenger's Seat w/ Seat Position Memory)
Power Tilt and Power Telescopic
Power Trunk Lid
Power Window (LHD)
Power Window (RHD)
Pre-Crash Safety System
Rear Fog Light
Rear Sunshade
Rear Window Defogger (LHD)
Rear Window Defogger (RHD)
Remote Control Mirror (LHD)
Remote Control Mirror (RHD)
Shift Lock
Sliding Roof
Starting (LHD)
Starting (RHD)
Steering Lock (LHD)
Steering Lock (RHD)
Stop Light
Taillight (LHD)
Taillight (RHD)
Theft Deterrent (LHD)
Theft Deterrent (RHD)
Tire Pressure Warning System
Vehicle Dynamics Integrated Management (LHD)
Vehicle Dynamics Integrated Management (RHD)
Wireless Door Lock Control (LHD)
Wireless Door Lock Control (RHD)
Just read your other post, you have a scmfancy new GS not a bogan one from before 2015 so my schematic may not apply, but the point is made. All of those codes were showing because the fuse blowing essentially told all those ECUs that the car wasn't on, hence the loss of communication.
I would still pull the map light thing down and disconnect it. Let me know if you require assistance in doing so.
Cwang is the electric schematics king. Like Peasodos is the mechanical Dr. Frankenstein. Together, they can turn any GS into whatever monster car you want. Or just keep it running. Hats off to you two for always helping. Soon I will need your help with the triple beam headlights.
Cwang is the electric schematics king. Like Peasodos is the mechanical Dr. Frankenstein. Together, they can turn any GS into whatever monster car you want. Or just keep it running. Hats off to you two for always helping. Soon I will need your help with the triple beam headlights.
Haha too kind. I'm not in the league of Peasodos, I haven't created a monster quite yet but thanks for the message. BCLexus always posted up helpful information like this for anyone who asked but he left (did he pass or just rage quit?). There is zero GS community where I live so it can be hard to get help, this forum is amazing. Looking stuff up, I certainly learn something new every day - I'm overwhelmed by the amount of electronics working under the skin of our cars, it's next level.
Just read your other post, you have a scmfancy new GS not a bogan one from before 2015 so my schematic may not apply, but the point is made. All of those codes were showing because the fuse blowing essentially told all those ECUs that the car wasn't on, hence the loss of communication.
I would still pull the map light thing down and disconnect it. Let me know if you require assistance in doing so.
Its under warranty and been left at the dealer but they weren’t sure the first time it went. Both times it went off at start up never during driving and a week apart - once it was raining the other time warm and dry.
I don’t understand electrics very well - why would you start at the map light? I mean they could disconnect it but then how could you know for sure without losing the map light functionality (not that it’s a big deal). But if you d/c map light wouldn’t that trigger a fault?
Would the dealer or a good auto electrician be able to fix this because only had this car 2mths and been PITA! Are you Aussie?
Its under warranty and been left at the dealer but they weren’t sure the first time it went. Both times it went off at start up never during driving and a week apart - once it was raining the other time warm and dry.
Oh that's good that it's covered. Just frustrating no doubt.
Originally Posted by mazstar
I don’t understand electrics very well - why would you start at the map light? I mean they could disconnect it but then how could you know for sure without losing the map light functionality (not that it’s a big deal).
I'd start there because you mentioned the rain sensor being loose, it's your only clue. The wiring could be damaged as it has moved. According to the diagram posted above, the rain sensor plugs into the map light thing above your head. If you isolate that, you've possibly removed the source of the shorting. It has 3 wires, 12v, 0v and a data bus, that could be it.
Originally Posted by mazstar
But if you d/c map light wouldn’t that trigger a fault?
Would the dealer or a good auto electrician be able to fix this because only had this car 2mths and been PITA! Are you Aussie?
Our cars don't have the fancy SOS and garage door opener systems above our head in the map light unit like the yanks do(we get a lovely blank bit of plastic instead) so it may not throw check engine code. If it does show an error there is nothing to worry about though.
Intermittent faults are very difficult to fix as they aren't always easy to recreate. If they rule out the map/rain assembly then....I'm not sure, I really hope it's that.
The fact that the sensor came off means someone may have had it off before??? I don't think they just fall off, perhaps the windscreen has been replaced and that is why the sensor was damaged? Does the windscreen say Lexus in the corner?
Worst case,it could be a fault in a relay, in a wiring harness, in a computer itself. They may start wiggling wires , I'd also be scanning to see if any computers are offline. Hopefully it blows in their possession. I'd say if it becomes too hard, they'd get their master technician in or their best auto electrician in the state. Hopefully it doesn't get to that.
Sorry for the long winded post. Yes I'm in Sydney, although my list of cars doesn't make it so...there are a surprising number of Americans driving around Australian cars!
Oh that's good that it's covered. Just frustrating no doubt.
I'd start there because you mentioned the rain sensor being loose, it's your only clue. The wiring could be damaged as it has moved. According to the diagram posted above, the rain sensor plugs into the map light thing above your head. If you isolate that, you've possibly removed the source of the shorting. It has 3 wires, 12v, 0v and a data bus, that could be it.
Our cars don't have the fancy SOS and garage door opener systems above our head in the map light unit like the yanks do(we get a lovely blank bit of plastic instead) so it may not throw check engine code. If it does show an error there is nothing to worry about though.
Intermittent faults are very difficult to fix as they aren't always easy to recreate. If they rule out the map/rain assembly then....I'm not sure, I really hope it's that.
The fact that the sensor came off means someone may have had it off before??? I don't think they just fall off, perhaps the windscreen has been replaced and that is why the sensor was damaged? Does the windscreen say Lexus in the corner?
Worst case,it could be a fault in a relay, in a wiring harness, in a computer itself. They may start wiggling wires , I'd also be scanning to see if any computers are offline. Hopefully it blows in their possession. I'd say if it becomes too hard, they'd get their master technician in or their best auto electrician in the state. Hopefully it doesn't get to that.
Sorry for the long winded post. Yes I'm in Sydney, although my list of cars doesn't make it so...there are a surprising number of Americans driving around Australian cars!
Yikes. The windscreen is genuine Lexus. They gave me loan car so I’m going to say they keep it till they figured out the cause. Thank you for suggesting things - I saw an older post here where someone said they blew fuse due to playing around with the rain sensor. I understood it meant some wire had to be exposed and was touching another wire or metal? I really should learn electrics!
One of the codes said short to ground BSM so originally I thought maybe a dodgy sensor or last collision. Lexus say they have no history of this fault from previous owner who only ever serviced their car there.
What I don’t uNderstand is if the centre light console is still working then how could it be the cause of the problem? I would have thought the items not functioning on that fuse would be the cause of the problem? Power windows, high beams, haven’t tested whether the rain sensor is working or not and the BSM will turn on and off but then go straight to fault.
UPDATE: Car been in for a whole day and they want it for another day at least. Apparently fault not related to rain sensor.
They think it may be down to wiring or sensor for BSM. They thought it could have been pedestrian sensor but seems like fuse blew after it was deactivated.
I was worried that they wouldn’t replace the gel pad for rain sensor as it might have been contaminated but apparently it works as it should be.
Ive got to say Lexus service seem pretty thorough and apologetic but let’s see if it’s fixed for good will keep updated for further reference - I find old posts never tell the outcome which could help future people.
They returned my car after 2 days but said if it happens again while waiting for the part we can get loan car if we want but they give you a UX.
I would rather have my car but not having power windows and high beam is a safety issue.
They blew thru so many fuses that they’ve had to give me a non fitting fuse that means I can’t put fuse cover back. I’m glad the issue kept happening because last time they replaced the fuse and it was fine.
It was the 10A LH-IG fuse as you said.
Apparently the owner prior never had any issues so it’s strange suddenly something like this occurs?
Loose rain sensor causing fuse to blow?
so my schematic may not apply, but the point is made. All of those codes were showing because the fuse blowing essentially told all those ECUs that the car wasn't on, hence the loss of communication. 
