2013 Yaris 1.33vvt Brake lights/ABS warning. Help needed.

[Sharkey22]

Hello all. I have lost all brake lights on my Yaris. I have checked all the obvious things. bulbs, brake light switch and fuses and found no faults. I replaced the switch as it is inexpensive but the old one checks out fine. Is there a relay in the circuit? I suspect the ABS light coming on after a random period is part of the same problem. It goes off with the ignition and then comes back on after random period.

Any advice much appreciated.

Thanks.

[flash22]

get the codes read, brake lights are a fairly simple circuit are all 3 brake lights out? how have you checked the bulbs?

[Sharkey22]

Thanks for replying Bob.

It is a 2013 RHD car.  All 3 brake lights are out. I removed the bulbs to test them with a 9 volt Battery, both filaments (stop and tail) in each bulb are intact and lighting (no internal shorts tested with a DMM), high level LED array the same. Codes show a switch issue. I have replaced the switch although the original switch checks out fine. It is actually 2 switches in one unit, one normally closed, the other normally open which swap duty when the pedal is depressed. I am probably going to purchase a genuine Toyota part but I suspect the issue lies slightly deeper. 

[flash22]

the switch has 2 circuits one does the brake lights the other is for the ABS/ECU

you can link the switch connector out you should get 12v to the bulbs, check the 12v at the rear lights using a body ground if you get 12v you know its a ground issue

any signs of water ingress in the boot/spare wheel well?

 

edit. the switch may test fine but it may be failing under load

[Sharkey22]

Hello Bob. Apologies if this is a lot of questions.

I have checked that the ground on the bulb sockets is intact with continuity to chassis ground. It is of course a common ground with the side lights which are fine.

I tried bypassing/linked out the switch yesterday and was still getting nothing at the bulbs. 

I will check that I have 12v on the switch plug 

Is the switch directly switching the brake lights or would it be controlling a relay or body control module?

Should there be direct continuity between the switch and the bulbs, like in an older vehicle? If so would it be safe (as a test) to run a wire directly from the switch to the brake lamp sockets? I don't want to blow any electronics by injecting 12v into the system where I shouldn't.

I presume the heavier blades on the switch are for the lights and the smaller blades are for the ABS/ECU connections. See attached pic.

Thanks again for your assistance.

[Sharkey22]

Hi Bob, I checked the switch connector. No voltage on the switch. Absolutely no moisture in the spare wheel well either. Grounds on lamp holders also good.

Where to next?

Ian.

[flash22]

sorry i didn't see your other post

yes thicker blades = higher current

pull the STOP and IG2 fuse and replace, check you have a 12v feed to the fuse

do not backfeed the circuit

[Sharkey22]

Ah, no problem. I have not made any changes or bodged anything. 

I removed and checked IG2 and STOP fuses with a test bulb to ground. They are good and have 12v on them, and for good measure checked every other fuse in the 2 fuse boxes except the larger form ones.  All are intact. 

Ian. 

[flash22]

so the problem is in the wiring somewhere between the fuse and the brake light switch - The next step is to look at connector 3C behind the glovebox iirc pin 12 green

 

had any issues with the front washers not working?

[Sharkey22]

Hi Bob, Front washers are fine. All of the green wires are on the larger, (higher current?) pins (1,2,4 and 8). Pin 12 is a black wire. I have attached a photo of the 3C connector.

I disconnected the Battery and re-seated all the plugs. I will check for continuity to the switch tomorrow.

There is a permanent live on the brake light switch but it is on the low current ABS/ECU part.

Do you have the schematic or service manual? Can it be downloaded from Toyota? There is no paper Haynes for the XP130.

 

Thanks again. Ian.

[flash22]

black pin 12 should be the 12v feed for the stop circuit - brake light switch

 

feed to switch - 3C pin 12 - black

Switch - black in, green out

into a splice A62 (7,11)

return from splice - 3C pin 25 - green

Output to rear - 3D pin 19 - light blue

 

 

 

P1045-8

 

 

 

[Sharkey22]

Hi Bob,

The fault was the wire from 3C pin 12 to the switch. I have put in a temporary wire from pin 12 to the switch and now have brake lights and no ABS warning lights.

Not sure how a wire in the loom fails. I guess the easiest fix is to run a new permanent wire. 

Ian.

[flash22]

cut it back about 50-100mm from the connector splice in a new wire and just overlay it, soldered or uninsulated barrel crimps and heat shrink

[Sharkey22]

Hi Bob,

I measured 3.45 amps on the circuit.  I replaced the wire with what I had handy which is a slightly heavier gauge. Was surprised how small the original wire is considering the load. Anyway all is good now. Job done.

Thank you very much for your clear guidance. I could not have found the fault. 🙂

Ian.

 

 

[flash22]

3.4 amps

16/0.2 (0.5mm²) thinwall is rated to 11 amps thats about 1.6mm in diameter

[MikeSh]

2 hours ago, Sharkey22 said:

Was surprised how small the original wire is considering the load.

It can be visually misleading. OEM wires tend to have very thin, but tough, insulation, so they look small compared to whatever stuff you've probably got. But the metal cores are beefy.

[flash22]

17 hours ago, MikeSh said:

It can be visually misleading. OEM wires tend to have very thin, but tough, insulation, so they look small compared to whatever stuff you've probably got. But the metal cores are beefy.

As I posted above the term is Thinwall - a thinner coating but more resistant it reduces costs, weight and bundle size in a loom

[MikeSh]

5 hours ago, flash22 said:

a thinner coating but more resistant

Yes, I find it's a b***er to strip 😬

[flash22]

The Knippex or draper auto strippers do the trick, now 4 AWG and above is a pain

[Cyker]

Wow good job finding that!

Very unusual fault. Rodent assisted perhaps?

[MikeSh]

2 hours ago, flash22 said:

The Knippex or draper auto strippers do the trick, now 4 AWG and above is a pain

I have some strippers (ooh la la) but it's usually when I'm fishing a wire out of a loom and stripping a bit off without cutting the wire, so I can solder a tap off.

While hanging upside down with my head under the dashboard. (Like when I was picking up feeds for the parking sensors you helped me with a while back.)

[TonyHSD]

Good job here. 
Rodent assistant usually happens on single wires but possible in the loom too. Sometimes wires can get damaged by vibrations and got insulation done then shorten themselves and burnt out or simply cut off. 
This is so typical for some other brands cars under the vw group. 

[Cyker]

It's surprising to happen with a Toyota, but as you say much more common with certain other marques...!  

[Sharkey22]

On 6/5/2024 at 8:01 PM, Cyker said:

Wow good job finding that!

Very unusual fault. Rodent assisted perhaps?

No rodents. I am as surprised as anyone. The car is not kept in a typical rodent prone environment and there is absolutely no evidence of rodent activity.

It would of course be interesting to know the cause of the original fault but I think that would be a way too invasive and unnecessary process.