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Auris Bonnet switch fuse?


farenheit
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I'm in a bit of a pickle here, only recently bought a 2017/66 auris hatchback and today I realised after I had the bonnet open that cars display didn't indicate that my bonnet was open.

I am really confused. I thought it did?? I checked the switch cable and it's connected to the latch.

Is there a fuse I can check?

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Its possible that there may not be separate fuse but check in your owners manual. If no separate fuse is shown in the manual then it's likely it is incorporated with another circuit. Check all the fuses as one may have blown. Its also worth opening and closing the bonnet a few times as this can sometimes solve the problem. Also see if the bonnet is engaging into the lock hope this helps.:smile:

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Do these come with an alarm as standard? Wouldn't this affect the alarm. If it thinks it's closed when it's open, then technically it can get broken into from the bonnet without triggering the alarm.

Where would I find the alarm fuses, wonder if they're connected...

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It quite possibly that the bonnet is linked into the car alarm but you need to look in the owners manual to see what it says about the alarm. Does the fusebox chart mention a separate fuse. Have you tried setting the alarm and leaving the bonnet slightly ajar to see if it still sets the alarm.

Has the car display definitely got a bonnet open light and did you notice the light was on when you last opened the bonnet.It might sound like basic questions but sometimes its easy to miss these things.:smile:

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The car display shows bonnet "closed" when it' is actually in fact open. Or should I say, the display doesn't change when you open bonnet. Isn't the alarm just set by locking via remote?? And this wouldn't really test anything as car thinks bonnets closed regardless lol. Couldn't locate an alarm fuse.

Need to do some more digging...

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It sounds like there might be a malfunction with the bonnet sensor or the connection between the sensor and the car's display. The alarm system is typically armed by locking the car via remote, but the bonnet sensor is supposed to trigger an alert if the bonnet is opened while the alarm is armed.

If the display doesn't change when the bonnet is open, it indicates an issue with the sensor or its connection to the display unit. This could be a wiring problem, a faulty sensor, or a malfunction in the display unit itself. It's a good idea to check the wiring and connections first, and if everything seems fine, you may need to have the sensor or display unit inspected by a mechanic or an auto electrician to diagnose and fix the issue:smile:.

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During a service at a Toyota main agent on our Auris, some years ago, the technician, perhaps in a 'devil-may-care' moment, or maybe because he wasnt very able, sprayed lots and lots of a white grease over the bonnet lock, but also over the top hose and the radiator.

I noticed that after a day or so, this had started to go sticky, hardening a little like a slow-drying gloss paint.

I wonder if some of a similar !Removed! has been put onto your bonnet micro switch, and 'glued' it closed?

A spray of WD40 or similar (a white spirit type base?) may soften the grease and allow the switch to work properly again. 

Might be worth a try?

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I had never seen the bonnet open warning on my 2016 auris. I was surprised to see a micro switch too. Looked to be green, possibly stuck, so i sprayed wd40 on it.

Then i thought id test the circuit by bypassing the switch with a short. It made no difference on the dash display.

It must be alarm related.

If the switch is corroded and stuck closed, im happy for it to remain that way. my Auris is not exactly on a car thiefs shopping list.

The next time i have techstream connected i will check to see if theres an open/closed sensor reading for it.

Compress_20240407_084316_6417.jpg

Compress_20240407_084315_5584.jpg

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3 hours ago, solero said:

I had never seen the bonnet open warning on my 2016 auris. I was surprised to see a micro switch too. Looked to be green, possibly stuck, so i sprayed wd40 on it.

Then i thought id test the circuit by bypassing the switch with a short. It made no difference on the dash display.

It must be alarm related.

If the switch is corroded and stuck closed, im happy for it to remain that way. my Auris is not exactly on a car thiefs shopping list.

The next time i have techstream connected i will check to see if theres an open/closed sensor reading for it.

Compress_20240407_084316_6417.jpg

Compress_20240407_084315_5584.jpg

Thanks for this, I only just bought the car in Feb and never really had to open the bonnet until I decided to check the oil levels and wondered why it never registered an open bonnet. So, yeah I'm none the wiser to know whether it does or doesn't. I just assumed as it indicates every other entry open (all doors and boot).

So how would it work for an alarm? I'm guessing bonnet opening would trigger the alarm, however I unplugged it (the bonnet latch switch) and locked the car and alarm didn't go off.  So what exactly does it do... Im genuinely interested.

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My bonnet switch is definitelyy working with the alarm. If bonnets closed and you arm lock. The lock symbol starts flashing after 30 seconds. Opening door with physical key triggers alarm.

If you leave bonnet open, and arm, it start flashing immediately, so doesn't arm itself. Opening door with physical key does not trigger alarm.

So all doors and bonnet need to be closed to arm alarm.

 

Screenshot_20240407-164907.png

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I thought I'd disconnect my switch and lock the doors and check the alarm light. It still armed itself. Really weird. It was solid for about 30 secs and then started flashing, with the switch disconnected.

Something is definitely not right.

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Sounds like your microswitch is stuck in the open circuit state. So disconnecting it makes no difference. Try adding a jumper wire like i did and see if that changes its behaviour. The switch may be configured/wired to go close circuit when boot is opened.

Its difficult to test the switch directly with a multimeter as the pins are fairly deeply recessed.

If the bypass wire does change behaviour then try wd40 and agitating the push switch under the metal lever.

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I did get a garage to check it and they just exposed/scored abit of the cable and used a tester (those bulb ones) which didn't light up on either wire. They just said there's no power coming through either wire based on the above assumption.

Will have to try and find some time this week to grab some wd40 after work, if not on the weekend.

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2 hours ago, farenheit said:

I did get a garage to check it and they just exposed/scored abit of the cable and used a tester (those bulb ones) which didn't light up on either wire. They just said there's no power coming through either wire based on the above assumption.

Will have to try and find some time this week to grab some wd40 after work, if not on the weekend.

Scraping exposing wires makes me cringe. Its likely 5v signal supply, so may not show on 12v probe. Also voltage may not show until alarm is actually armed. I will try and back probe voltage when i get a chance.

Does your car alarm actually sound on a physical key opening trigger after arming?

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Q2. Does your car sound a warning buzzer when the door is left ajar and keys are in ignition?

The reason i ask is that the schematic shows that the buzzer shares the same ground wire as the bonnet/hood switch.

It could be that a past owner has cut ths ground wire in a diy attempt to silence the annoying warning buzzer.

The proper way to disable this warning is to do it using techstream custom option.

 

Screenshot_20240409-010550.png

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Does your car alarm actually sound on a physical key opening trigger after arming?

Yes. Didn't try it with the key, had the window open and put my arm in to open the door unsuccessfully and sounded the alarm. Presumably I activated some sensor.

Does your car sound a warning buzzer when the door is left ajar and keys are in ignition?

Yes, however mines a keyless start. I tried a different approach by leaving the passenger window open and locked the car and got the warning.

Not sure if this is the same test

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Yes. those tests sound good.

It tells us your alarm is working, and your buzzer is working.

For the last test, you will need to disconnect the bonnet sensor and test the voltage across both wires.

Use a multimeter to test the voltage across both pins after arming alarm. If you get a sensible voltage reading (3,v, 5v, 12v) your wiring is good.

Otherwise you have a possible break in one of the wires.

Did you try the loop wire test i mentioned earlier?

 

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Yes tried the loop wire test, same result as yours.

I disconnected the plug, and locked the doors. Alarm light was flashing, indicating that it wasn't armed. I then added the loop, whilst the switch plug was disconnected and locked the car. The alarm light was solid for 30secs and then started flashing like it should. Indicating that it is now armed. So I guess, from all this, there is no display on the 4" TFT to indicate an open bonnet. Strange.

P.S

Also tried with key, armed and opening with a key sounds the alarm. Sounds like it has a separate buzzer/siren as well as the horn. My previous MK1 hybrid alarm only used the horn. This MK2 sounds more premium coming from a MK1.

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6 hours ago, farenheit said:

Yes tried the loop wire test, same result as yours.

I disconnected the plug, and locked the doors. Alarm light was flashing, indicating that it wasn't armed. I then added the loop, whilst the switch plug was disconnected and locked the car. The alarm light was solid for 30secs and then started flashing like it should. Indicating that it is now armed. So I guess, from all this, there is no display on the 4" TFT to indicate an open bonnet. Strange.

P.S

Also tried with key, armed and opening with a key sounds the alarm. Sounds like it has a separate buzzer/siren as well as the horn. My previous MK1 hybrid alarm only used the horn. This MK2 sounds more premium coming from a MK1.

From your loop wire test, it passed. Which seems to imply your bonnet microswitch is stuck in open circuit. So alarm thinks that bonnet is always closed.

On mines leaving bonnet ajar (not fully latched) with wiring connected prevents the alarm from arming. 

Yes, I confirmed that bonnet switch is only used with alarm, not for 4" tft display.

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19 hours ago, farenheit said:

Yes tried the loop wire test, same result as yours.

I disconnected the plug, and locked the doors. Alarm light was flashing, indicating that it wasn't armed. I then added the loop, whilst the switch plug was disconnected and locked the car. The alarm light was solid for 30secs and then started flashing like it should. Indicating that it is now armed. So I guess, from all this, there is no display on the 4" TFT to indicate an open bonnet. Strange.

P.S

Also tried with key, armed and opening with a key sounds the alarm. Sounds like it has a separate buzzer/siren as well as the horn. My previous MK1 hybrid alarm only used the horn. This MK2 sounds more premium coming from a MK1.

From your loop wire test, it passed. Which seems to imply your bonnet microswitch is stuck in open circuit. So alarm thinks that bonnet is always closed.

Yes, I confirmed that bonnet switch is only used with alarm, not for 4" tft display.

I managed to measure voltage today as shown 8v. Also a picture of the microswitch. That greenish area button is what you want to free up under the lever. The sample microswitch picture shows it more clearly.

 

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Screenshot_20240411-152700.png

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Need to get a multimeter first lol

I do have techstream...

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On 4/11/2024 at 3:39 PM, farenheit said:

Need to get a multimeter first lol

I do have techstream...

Doesn't techstream show you a sensor reading for the bonnet switch?

Another simple test would be to arm the alarm with a window open. Then pull the bonnet lever under the dash to see if that triggers the alarm. 

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Although I have techstream, I have no idea how to use it 😂 Opening bonnet whilst armed, triggers alarm.

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I couldn't find a bonnet sensor with Techstream...

Doors and boot switches are easy to check/see tough.

The only mention Techstream tells about bonnet, it's under the "main body" ECU, "data list", there is a set of parameters called "engine hood door" (see picture).

But I didn't see any of those parameters changed while I opened the bonnet. Perhaps they are related to an alarm system which I haven't.

 

engine hood.JPG

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17 hours ago, farenheit said:

Although I have techstream, I have no idea how to use it 😂 Opening bonnet whilst armed, triggers alarm.

I wouldnt worry about it. Your alarm system appears to be working fine, as per your hood open test whilst armed.

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