Mk3 brake light feed

[MikeSh]

2018 hybrid.

I'm trying to sort out some aftermarket front parking sensors and need to get a 12V brake light signal. The hardware is behind the instrument cluster, so the obvious place to get this is from a brake pedal switch. But I suspect there is more than one switch and possibly it all goes via a control unit and there isn't a suitable feed at the pedal.

Any ideas? Or point me at a wiring diagram.

[Vins213]

53 minutes ago, MikeSh said:

2018 hybrid.

I'm trying to sort out some aftermarket front parking sensors and need to get a 12V brake light signal. The hardware is behind the instrument cluster, so the obvious place to get this is from a brake pedal switch. But I suspect there is more than one switch and possibly it all goes via a control unit and there isn't a suitable feed at the pedal.

Any ideas? Or point me at a wiring diagram.

I have an electromagnetic front parking sensors with its button installed near the lights level...the 12v from the OBD port, when I need to use the front sensor, I switch it on

why are you searching for brake light signal?

[MikeSh]

8 hours ago, Vins213 said:

why are you searching for brake light signal?

Because I'm not the only one who uses the car and the system is meant to be automatic. I can't expect other people to remember to turn it on/off as needed.

This is the way the instructions say it's meant to be wired.

[Vins213]

5 hours ago, MikeSh said:

Because I'm not the only one who uses the car and the system is meant to be automatic. I can't expect other people to remember to turn it on/off as needed.

This is the way the instructions say it's meant to be wired.

The wiring is explained here

https://www.toyota-tech.eu/aimuploads/8eab1a40-bb11-4dbd-8b54-7db0f147e36a/YarisLHDTpaFront_PW5010D110_AIM003%20970-8.pdf

 

not a 12v brake light signal, page 37

[jthspace]

😵‍💫

[MikeSh]

3 hours ago, Vins213 said:

The wiring is explained here

https://www.toyota-tech.eu/aimuploads/8eab1a40-bb11-4dbd-8b54-7db0f147e36a/YarisLHDTpaFront_PW5010D110_AIM003%20970-8.pdf

 

not a 12v brake light signal, page 37

Doesn't really help with my system as it is just a "do this" instruction that doesn't really show what each wire is doing.

I need 12V when the brake pedal is pressed.

[Vins213]

5 minutes ago, MikeSh said:

that doesn't really show what each wire is doing

it is an activation/deactivation when the car goes at minimum speed

7 minutes ago, MikeSh said:

I need 12V when the brake pedal is pressed.

in this case, you can take the 12v from the third stop with a long wire that you can hide easely 

[flash22]

What make/model kit are you installing ?

[MikeSh]

4 hours ago, flash22 said:

What make/model kit are you installing ?

It's actually an existing 400ex, iirc, with a canbus device. It's not working reliably and having had a couple of goes at it without success I want to get it wired per the basics.

From what I've seen online the are only 4 wires on the brake pedal switch, and all simple 12V, so I can probably work out which I need. (Reversing light feed would be nice too, but not essential at this stage if at all.}

[flash22]

It doesn't use a brake light signal or reverse signal it's speed dependent (VSS), it's a known issue on the 2018 yaris iirc there is a TSB

TPA 400 5 wires from the unit - Pos, Neg, VSS, Sounder - pos and neg, stand-alone unit no Can Bus

the disable switch is optional, The cancel circuit is internal to the module

[MikeSh]

1 hour ago, flash22 said:

It doesn't use a brake light signal or reverse signal it's speed dependent (VSS), it's a known issue on the 2018 yaris iirc there is a TSB

Sorry, I missed a word out in my last post - it's a Steelmate 400EX.

First sentence in my OP:

On 8/29/2023 at 3:57 PM, MikeSh said:

I'm trying to sort out some aftermarket front parking sensors

But are you suggesting that even an aftermarket canbus/speed unit won't work properly?

[flash22]

Ah, Assumption and lack of info ,Toyota system is known as TPA 400

I will have a look

Ah I see, it's a standalone unit, it uses a reverse and brake as a cancellation

you can pick up the reverse signal at the Instrument panel junction box (behind the glove box)

Click to enlarge

3D - Pin 29 - late 2014 onwards (earlier cars use pin 28)

 

I will have to look up the brake light as yours is a 2nd facelift

[MikeSh]

2 hours ago, flash22 said:

2nd facelift

I never knew there were two.

[flash22]

Brake light should be on 3D, pin 10, green wire - confirm it with a meter

1st face lift 2014 - 17

2nd facelift 17 - 20

[MikeSh]

3 minutes ago, flash22 said:

Brake light should be on 3D, pin 10, green wire - confirm it with a meter

Thanks. That's useful both being in the same location as I can run a 2-core over there. Should be easy enough ... 🤣 

[MikeSh]

On 8/31/2023 at 12:25 PM, flash22 said:

Brake light should be on 3D, pin 10, green wire - confirm it with a meter

Got the reverse OK on 29 but brake isn't on 10. I checked the others in that column and it's none of them either. The are plenty of green wires in other positions but 19-36 are very close packed small openings so it's hard to test them, especially while pressing the brake pedal with a stick. (I actually stripped a patch off wire 29 to clip onto and confirm.)

Any other likely candidates?

[flash22]

3D pin 19

3C pin 25 - 3C is the connector below, pin 25,  top row middle column - ignition on, brake depressed

 

ps. for testing, use a t pin or darning needle if you can't probe it

[MikeSh]

16 minutes ago, flash22 said:

3C is the connector below

The one I'm on is at the bottom ... 

I'll have another grovel tomorrow morning.

[flash22]

You don't have it on there either - as that is the case take it from the brake light switch or passenger footwell

there are different switches depending on the year and model

4 pin white plug

or

7 pin black plug

 

[MikeSh]

22 hours ago, flash22 said:

3D pin 19

That was the charm.

What happened was that I initially tested for brake on the top connector but got nothing. Then I looked harder at the picture you posted and reckoned the bottom one looked more like it, and logically I thought they'd be coded 3A,B,C,D going across then down.

When I found reverse there it seemed to confirm I'd found 3D, but of course no brake.

When I got on it today I could quickly see there wasn't even a wire in 19 of the bottom connector, so tested 19 (a blue wire) in the top one and bingo - live when brake pressed. So I've picked that and the reverse up and in early testing on the drive it seems to be working.

I noticed that pin 29 on both connectors is a red wire ... I wonder if they are looped together. I should have tested that too but having for what I needed I just wanted to finish the job off.

Thanks for the help.

[MikeSh]

I'm quite curious as to why the Toyota speed detection in the 2018 doesn't work.

If it is a problem with the canbus signal that would explain why mine didn't seem to work reliably either.

[flash22]

It's just there is no VSS input on your aftermarket unit, it is more than likely uses a motion switch or accelerometer

VSS is its own PWM signal that output from the ABS (backup VSS in the gearbox) the main ecu converts this to CAN bus, most systems use a VSS tho

 

The brake lights get complex as it shows all models and bulb types - yes the pins are linked internally in that junction box 3A and 3B on the back, 3C and 3D on the front

 

here is an example of Junction box internal wiring

 

 

[MikeSh]

2 hours ago, flash22 said:

It's just there is no VSS input on your aftermarket unit

It had a separate canbus speed unit, but I was suspicious about its operation. So I have reverted the system to 'standard' operation to eliminate one cause of it not working reliably.

[MikeSh]

2 hours ago, flash22 said:

here is an example of Junction box internal wiring

That's a lot of jumpering 😗

[flash22]

That's just a part one of 1 page, with different engine and dash looms you can have 40-60 different configurations

the can bus adapter will have been a universal one it would be used for the brake and reverse signals, according to your destructions there is no VSS in