ABS error 36 - open circuit - left front speed sensor or circuit

[fenixus]

now i have just one single ABS error code repeated over and over since engine start (no driving) after clearing ABS codes:

36 - open circuit - left front speed sensor or circuit

... so what do you think, replace the sensor first and then see what happens?

there was no cut wiring or anything like that I could see in the wheel well on driver side last time i checked.
I also believe the rest of wiring is fine, but can double check visually ... just need to figure out through where this wire travels to the other side of car ...

car is 2002 Toyota Solara SLE V6 (1mz-fe engine) @ 124k miles, ABS unit is the Bosch model with ECU integrated in actuator body (no traction control on this one).

thanks for opinions.

[71Corolla]

Isn't it just a matter of testing the resistance of the sensor? You'll either get a proper reading, (I'm guessing, maybe 40 ohms) a short, or an open circuit.

[fenixus]

Originally Posted by 71Corolla

Isn't it just a matter of testing the resistance of the sensor? You'll either get a proper reading, (I'm guessing, maybe 40 ohms) a short, or an open circuit.

huh, if you can dig up for me some solid ohm value for a working correctly sensor then I would be very grateful

I was browsing FSM on Brakes, but found only a chapter about ABS actuator, so far nothing on ABS speed sensors ... anybody knows how to check the sensor before moving to checking the whole circuit ?

[TedL]

Just thinking aloud...can you easily swap sensors, or even just connections?

[fenixus]

ah, found it, finally Brakes PDF provided a link to gen4 Diagnostics FSM and page index (537 for Bosch ABS system). reading now. i think it's more complicated than a resistance check of sensor though ...

[fenixus]

Originally Posted by TedL

Just thinking aloud...can you easily swap sensors, or even just connections?

nah, i think it's not that easy to swap them ... I don't even know if this is considered easy to remove/replace them ... have never done that yet ...

i will read Diagnostics FSM and see what they suggest. they have some tricky way of checking the sensors ... at least in Denso flavor of this system, will see what Bosch came up with ...

[CWH5]

spec is .6-2.5k ohm ( this isn't a good check as the value is so wide but you can start there).
I would remove that sensor and the one on the other side and swap them ( no need to fully install just plug them in) and clear and recheck codes, if it didn't change then you have a problem in the harness or the ECU, if it did change its the sensor.

If the sensor is not seized in the hole this is an easy swap.

[fenixus]

Originally Posted by CWH5

spec is .6-2.5k ohm ( this isnt a good check as the value is so wide but you can start there).
I would remove that sensor and the one on the other side and swap them ( no need to fully install just plug them in) and clear and recheck codes, if it didnt change then you have a problem in the harness or the ECU, if it did change its the sensor.

how easy/hard is it to remove that sensor ? do i have to mess with CV joints or some tie rods or something ?
sorry, i've never touched any ABS components as of yet and never did myself any work on suspension yet ...

it was always appearing to me as kinda hard to do ... if that's fairly simple, i may try swapping them as suggested by you and fellow above.

[71Corolla]

Originally Posted by CWH5

spec is .6-2.5k ohm.

Did a bit of searching, that seems to be about right. I thought they were much less for some reason.

fenixus is the sensor connector reasonably accessible? Here's a pic of the sensor assembly. I don't think it will be that hard to swap out, but that depends on how much room you have to get the actual sensor out.

[CWH5]

Originally Posted by fenixus

how easy/hard is it to remove that sensor ? do i have to mess with CV joints or some tie rods or something ?
sorry, i've never touched any ABS components as of yet and never did myself any work on suspension yet ...

it was always appearing to me as kinda hard to do ... if that's fairly simple, i may try swapping them as suggested by you and fellow above.

No need to remove any suspension or axle components. this should be fairly ez unless the sensor is seized the the spindle, one 10 mm head bolt to remove then give it a slight twist then a small screw driver to gently pry it out.

I will note that i dont do this in practice, I have made a custom harness that changes the sensors to the other side of the ecu to do this check. This was done because of seized sensors.

[fenixus]

thank you guys
glad to hear it's not that hard (unless seized hehe).

only problem (for me) that in order to access the harness connector for sensor i will have again to unscrew and peel off both front fender liners have been doing it for the whole weekend back and forth haha ... seems like next weekend will be no different

first will measure the resistance of both, then will try removing the one on passenger side and connecting it to driver side.

also i found some software method of testing the speed sensor by FSM, gen4 Diagnostics, page 540 (Bosch system testing is same as Denso, just error code numbers are a tad different):
http://www.camrystuff.com/

namely, in a certain Diagnostics mode (Ts-E1 jumpered in DLC1 under hood) and driving car straight forward with no touching brakes for "several seconds" causes a faulty sensor to output an error code (numbered as 7x). this code can be then read by jumpering Tc-E1 terminals in DLC1. only a faulty sensor (or rotor) gives such code (per FSM)... not sure, maybe will try it first.

[fenixus]

and i found the resistance specs in FSM, page 554, just as you said, 0.6-2.5Kohm, confirmed.

I guess I will measure and see what comes up, if no good then I will be shopping for a new one.

[fenixus]

ok, this is not fun.

unplugged ABS sensor connector on both front wheels and measured resistance of sensor. FR (good, no errors) reads 1.04Kohm
FD (instant error) reads 1.06Kohm

I have unbolted ABS sensor on FD side and discovered it was a tad dirty, it had some metal particles on it (like it grinded a little), so i cleaned it up. sprayed both plug and socket with QD cleaner, tried checking continuity of plug terminals to ground, but found nothing interesting, maybe i was using wrong ground, i doubt it's the case though...

anybody knows how long the sensor tip should be, 1mm ?

After engine restart and clearing ABS codes, same thing, instant error 36 (FD sensor or circuit open).
What's worse I noticed that after short driving the other 2 codes I've sen before come back, they both relate to rear wheels ABS sensors ... what a PITA ... much more complicated than i thought ...

so I have actually 3 ABS error codes:
delayed 33 right rear wheel speed sensor signal malfunction
delayed 34 left rear wheel speed sensor signal malfunction
instant 36 open circuit in left front wheel speed sensor

...

[CWH5]

well with those 3 codes i would remove the main connector at the ABS ECU and inspect for corrosion, you can also check the resistance of the entire LF speed sensor circuit by checking the red and green wires( terminals 6 and 7) at that connector (Disconnected), the resistance should be about the same as you measured at the sensor itself (no more then 1-2 ohms more). Be very careful when checking voltage or resistance from the front of a terminal, you could open up the terminal by inserting a pin/paper clip or God knows what that is bigger then the male terminal thus causing a poor connection.

[fenixus]

good call, thank you. there was some dirt/sand around the connector, which i cleaned off roughly before attaching the new harness plug.
will do some more thorough cleaning with QD cleaner soon.

I will test resistance of sensors on ECU end to see if I have same readings or no, this should help.

also planning to do the speed sensor voltage testing (special diagnostics mode per FSM) and see what comes up with that.