ABS Warning Light

[sproutdreamer]

Our newly acquired old Yaris has started to show the ABS amber warning light intermittently. It self tests ok at start up but has come on and gone off a cpouple of times now.

My thinking (more likely hoping) is that this is probably a loose connector or a dirty or faulty wheel speed sensor. I have a OBD11 code reader (somewhere) and an old laptop

with diagnostic software installed but it is about 7 years since I used it. Cannot remeber what the software was or whether the detail on the diagnostics went down to the detail of individual wheel sensors?

Before I try and find the laptop and code reader have any of you experts any wise words about ABS and Yaris ABS warning lights.

I replaced a wheel ABS sensor on a Corolla about 2003 and it was a sod of a job to get the sensor out of the wheel hub boss and the sensor then was £120+ from Toyota which I could not afford but got one from a scrap yard (self removal- not sure you can do that these days with H&S, for £10 and it came out easily). I hope the Yaris is easier?

[Madasafish]

You need a multimeter. Set to read resistance.

Follow ABS cable from sensor at wheel to first connection under bonnet. Undo . Then test on sensor side the resistance.

Should be around 1.5K ohms.

Infinite = broken circuit/wire/

Zero = failed sensor.

 

Try front passenger side first - collects all crud. 

 

As it is intermittent, could be dirt between sensor and ABS ring mounted on drive shaft. So CAREFULLY remove sensor and check through hole in hub.  Warning - take great care .. sensors are not cheap ...Handle wire attached to sensor with care..it may have chipped plastic cover letting water in and corrosion.. so may be fragile.

 

Been there don e it on mark 1 Yaris.. sensor failed bought non OE part on eBay £35 which worked perfectly.

[sproutdreamer]

Thanks Madas that is good information.

I am going to try my OBD11 code reader and see what that throws up as it is wet and cold and not the weather for crawling around under a car. The problem is that as an intermittent fault it will probably show ok but there may be fault codes lying on the computer software showing which will show which sensor (if it is a sensor) is faulty.

I have charged up my old laptop with the diagnostic software, found the code reader - but where is the OBD11 diagnostic socket on a 04 Yaris? The Haynes manual shows a picture of a code reader in tools and equipment but does not tell where the socket is located.

Please anyone where is it?

[Madasafish]

The socket is:  pause whilst he checks -

  BUT OBD2 does not show ABS fault codes.. you need a Toyota code reader or suitable software of which I am ignorant.

 

[sproutdreamer]

Found the OBD11 socket to the right of the wheel under the clip off cover that houses a bank of fuses - why does the Haynes Manuals not show that, but then they are a bit rubbish anyway!

Ran the diagnostics and the software I was using ran all the checks and said everything was ok and there were no fault codes left in the system.

Would you expect an internittent fault with the ABS to have left a faullt record?

Prrobably a numpty question but I have only used a fault code reader/diagnostic software once before and that was about 7 years ago.

 

[Madasafish]

I would expect faults to be stored until cleared.That's how engine faults are recorded.

[Perfection]

Just to add for ABS fault diagnostics......

 

I recently had an intermittent fault on my Yaris 2010 with an ABS light on, the system will do a check at start up for any short or open circuit on the harness and the sensor.

If a previous fault has been recorded, the fault will be cleared if no fault is present for approx 1/2 mile of driving.

I believe on a Mk 2 Yaris (mine is a 2010) and the sensor resistance is approx 6M ohms. On a Mk 1 (and early corolla) is around 1K to 2K ohms.

I also have found that the easiest way to confirm if the harness from the sensor to the ECU is to measure the voltage on the connector pins to ground chassis. On a good connection it should have some thing like: Hi-side to chassis ground = 11V; Lo-side to chassis ground = Approx 0V. (Measure with the ignition position in position 2).

Doing this saves you a lot of time trying to locate the ECU connector pin.

 

Hope the above is helpful and make sense. 

My yaris ABS fault was fixed after confirming that the speed sensor in the wheel hub was faulty. I paid £45 for part and paid £20 for a local garage to remove and replace the part. I obviously did the diagnostic to save money....