ABS Warning light on!

[mikeso51]

Pulled out of the drive in the Yaris yesterday and noticed the ABS light hadn't gone out. Stopped the car and switched off.  Restarted, and light went out.  However within a second or two of pulling off it came on again, and is now permanently on whenever the ignition is on.  Spent today in the freezing cold taking all the wheels off and checking the sensor wiring was intact.  At the back I also removed the sensor connectors (which were clean and uncorroded) sprayed them with WD40 and replaced. I also checked the ABS fuse, which was fine. Bad news is the ABS still stays on.

Questions:

1.Does the ABS light need to be reset in some way, or does if do that automatically when the fault is fixed?  I tried disconnecting the Battery for a minute or two, but that had no effect

2. If the fault is a failed sensor, is there any easy way to identify which one it is?  I've searched on the web for code readers which will identify ABS faults, and the cheapest seems to be the Autel ML619. Does anyone know if this is any good?.  I am prepared to pay £80 odd for this reader if it will do the job and there is no cheaper solution.

Any help/suggestions greatly appreciated.

Mike

 

[Perfection]

You may not require a code reader, I did repair on mine a few months a go and simply reading the resistance and voltage measurements : Read here it may give some info...

Quote"

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....

 

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[mikeso51]

Thanks, that’s helpful, but how did you manage to access the connections to the sensors? At the back the pins are so deeply recessed inside the connector I could see no way of connecting to them, and at the front I couldn’t find an accessible connector. What am I missing?

[Perfection]

My problem was at the rear sensors. You need to jack the car up and remove the wheels. I managed to see and locate the plug and disconnected it from the sensor side in the wheel hub. You need to disconnect the plug in order to probe the test leads to measure the resistance and voltage.

You need proper axel stand to jack the car. 

[Perfection]

Hi Mike,

I read your question again and now I realised you had trouble accessing the pins in the connectors.

I had the same problem, what I did was use a paper clip and inserted into the deep hidden pins and then connect the electrical test leads into the paper clip.

Perfect.

[mikeso51]

Thanks perfect. I can connect ok to the female half of the connectors at the rear of the car using thin stiff wires attached to my meter probes. However I can’t make reliable connections to the 2 male pins deep in the connector on the hub. It’s almost impossible to see them even with a dentist’s mirror and strong light, I can’t tell whether they are touching the pins or not, and the two wires just keep shorting together. You must have the skill of a surgeon!  At the front of the car I could not find any accessible connectors to probe. Where are they?

Cheers

Mike

 

[Patonski]

Hi , id be interested to know the process for testing an abs sensor ?

Could anyone explain the procedure , I have a meter I could use.

Thanks

Stuart

[Perfection]

Mike,

Yes it was difficult to probe on the connector pins on the hub side.

I didn't need to check my front sensors as the fault was identified at the rear hub.

I believe the front sensors are mounted in a moulded metallic housing. The connector is not immediately at the tooth wheel. Do a Google on a picture so you understand what I am referring to. In my case I didn't need to locate the connector as the fault was at the rear hub.

The failure rate will be higher at the rear hub as the sensor get contamination from water ingress. I would try and rule out the rear sensors first before tackling the front.

Good luck.

 

 

 

 

[mikeso51]

Perfect

Thanks. Having spent an hour on my back trying to probe the ABS sensor pins without success I think I will give in and buy a code reader.  It will undoubtedly come in useful again.

By the way, I removed one of the front ABS sensors to check it out for dirt etc, and it was clear.  I traced the wiring back, and the connector seems to be high up in the wheel arch, behind the plastic splash shield. I think this shield would have to be removed for access. At this stage I will hold off on this until I know that the problem is here.  Looks like a lot of work.

 

Patonski

Old type sensor are magnetic reluctance devices, basically a magnet with a coil wound over them. They are relatively low resistance, usually a few hundred ohm or so, so easy to check with a multimeter.  Faulty sensors are usually open circuit.  The latest sensors are solid state.  I don't know what technology is used, but from what I've read they normally measure high resistance - a few megohm. I don't know what the failure mode is they may go open circuit or short circuit I guess.  Harder to test than the old type.  Biggest problem on the Yaris is making electrical connection to the sensors. The connector are tiny and not very accessible. See earlier messages.

[Perfection]

Mike, Stuart

The newer rear hub sensor resistance is about 6M ohms when it is working. The one that failed on mine measured much more higher than that, like 10M or more and has bad resistance to the housing of the wheel hub.

If you want to buy a Code reader, go for the mini vci, then down load the Toyota techstream. 

All for under £20 from eB**

This works well for the diagnostic.

[mikeso51]

Thanks for the tip. I’ve just ordered a mini vci reader for £14. Not sure I understand why you need to download software, but I guess it will become clear when I get the package. 

[mikeso51]

Well, got the ABS problem fixed today.

I bought the minivci code reader suggested by Mars(£14), and after some fiddling around with software got it set up on an old laptop. When I interrogated the car it came up with 3 faults all associated with the rear rhs abs sensor. Bought a new hub with integrated sensor for £39 all in, and fitted it today. After clearing the old stored fault codes all is sweetness and light (no light actually!}.

Out of curiosity I compared the old abs sensor with the new one before fitting it. Measuring resistance was inconclusive. Both sensors gave very high and unstable readings in the 10s of megohm range. More significantly,  measuring on the “diode” range of my multimeter, the old faulty sensor showed a reading of around 600mV with one polarity of leads, and around 800mV with the other. Measurements on the new sensor were around 1500mV and 2500mV. These measurements were with the hubs on the bench. It is, in my experience, very difficult to probe the sensor connector pins with the hub fitted to the car.

Hope this helps someone else. Definitely recommend the minivci reader if you have a suitable laptop available and are prepared to work out how to install the software (not that hard if you have a little computer experience). You need to know the Toyota model code for your car. NLP90 for my 1.4 D4D.

[Perfection]

On 21/01/2018 at 11:26 AM, stantheman1 said:

Hope you have as much enjoyment with your new car as you did with the Yaris, maybe you could pop over to this site now and again offering advice to other members.

 

On 21/01/2018 at 11:37 AM, Patonski said:

I have a 2008 Yaris d4d , thinking to change it in a year or so but not sure what to go for , I live and work in a town so its always short runs , so I am not sure if having a diesel is the right car , ideally I would like something a bit bigger than the yaris with more space for shopping , kids stuff or luggage if we go on a road trip.

Well done Mike.

The resistance measurement is a fiddle, totally agreed.