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Discussion Starter #1 (Edited)
Hello all!

This is my first post to the forum, but I've had my FJ for quite a while now. I have a stock 2012 with manual transmission. This winter has been good here in Utah with plenty of snow for skiing. This means the roads have also been entertaining (read: slick). Shortly after the 2nd major snow here my CE and A-Trac light came on the dash. I used my FIXD OBDII device to see the code and it shows C1401 Traction Control Valve RF Circuit Open, and C1402 Traction Control Valve RF Circuit Short To Ground. I have searched the almighty Google for these error codes and have come up somewhat empty-handed, aside from this link: https://www.troublecodes.net/ccodes/c1402/. I plan on taking it to the dealer to have them read the codes as well, but I figured I'd plumb the depths of knowledge on this forum to get an idea of what I'm up against. I'm fairly handy with my vehicles, doing much of the regular maintenance myself, so I do have some minimal mechanic skills. Can anyone tell me what these codes mean and how I can go about getting it repaired?

Thanks in advance!
 

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The OBDII description you found for C1402 is somewhat misleading ... a more informative for this code is "Malfunction in Front Speed Sensor LH Circuit".

Look for damaged cable to the left-front wheel speed sensor, corroded or contaminated contacts in the connectors, a loose sensor mounting bolt, metallic contamination on the end of the sensor, or less likely, a failing wheel bearing.

Damaged cables can be hard to detect, as the conductors inside the cable can be broken even though the outer insulation is intact. Inspect the cable carefully for any evidence that something hit it, pinched it, or got caught on it.

Pull the sensor itself, and verify that the plastic housing is not cracked, and that the tip is clean and there is no ferrous debris on it. When reinstalling it, verify that the mounting pad is clean and the sensor is seated properly.
 

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Discussion Starter #5
And the problem was??????
I've visually inspected everything on the front driver's side wheel speed sensor and wiring with no noticable problems. I then went on vacation for a few weeks. My next step will be to replace the sensor itself and see if that's the issue.
 

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Bear in mind that the actual conductor within the insulation can be broken if the cable is "stretched", while the insulation still appears intact.

I think it's more likely that the cable is damaged, rather than having an actual sensor failure on a '12 model, unless the wheel bearing itself is failing.

The magnetic "encoder ring" that the sensor "reads" is an integral part of the bearing.You can pull the sensor and make sure that no debris is present on the tip.
 

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Discussion Starter #7
Bear in mind that the actual conductor within the insulation can be broken if the cable is "stretched", while the insulation still appears intact.

I think it's more likely that the cable is damaged, rather than having an actual sensor failure on a '12 model, unless the wheel bearing itself is failing.

The magnetic "encoder ring" that the sensor "reads" is an integral part of the bearing.You can pull the sensor and make sure that no debris is present on the tip.
I didn't pull the sensor, I will do that today. Nothing was loose. I disconnected the wire and checked the connection, it was clear of any corrosion. I will triple check the wiring when I pull the sensor tonight.

This is my second FJ. I had to replace the left front hub (same one that's causing me problems now!) on my first one due to a failed magnetic ring, so I've been down this road before unfortunately. I'm hoping it's the wiring or sensor and not the hub. I want to avoid the old "replace everything one at a time until the light goes away" game.
 

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With recent driving through heavy snow, I think its more likely a cable problem than a failed sensor or failed hub.

Use an ohmmeter to verify that each conductor in the cable shows end-to-end continuity when it is put under slight tension. I think there are two series-connected sections of cable.

Approaching the problem by the blind shotgunning method ("replace everything one at a time until the light goes away") is absurd; careful failure analysis using a methodical approach will almost always isolate the root cause of the problem without wasting money replacing good parts.

If you have access to an oscilloscope, you can check the output signal from the wheel sensor by jacking up the wheel and spinning the tire by hand.
 

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Discussion Starter #10
With recent driving through heavy snow, I think its more likely a cable problem than a failed sensor or failed hub.

Use an ohmmeter to verify that each conductor in the cable shows end-to-end continuity when it is put under slight tension. I think there are two series-connected sections of cable.

Approaching the problem by the blind shotgunning method ("replace everything one at a time until the light goes away") is absurd; careful failure analysis using a methodical approach will almost always isolate the root cause of the problem without wasting money replacing good parts.

If you have access to an oscilloscope, you can check the output signal from the wheel sensor by jacking up the wheel and spinning the tire by hand.
I haven't tried the multimeter yet. But out of curiosity I disconnected the wheel speed sensor to see if the computer detected it. Sure enough it did. I *think* that means the wire if functional, as is the sensor itself. Correct me if I'm wrong, but I think that means the magnetic ring on the hub is the problem. I'm posting screenshots of my error codes with the sensor disconnected.
 

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Discussion Starter #11 (Edited)
With recent driving through heavy snow, I think its more likely a cable problem than a failed sensor or failed hub.

Use an ohmmeter to verify that each conductor in the cable shows end-to-end continuity when it is put under slight tension. I think there are two series-connected sections of cable.

Approaching the problem by the blind shotgunning method ("replace everything one at a time until the light goes away") is absurd; careful failure analysis using a methodical approach will almost always isolate the root cause of the problem without wasting money replacing good parts.

If you have access to an oscilloscope, you can check the output signal from the wheel sensor by jacking up the wheel and spinning the tire by hand.
I haven't tried the multimeter yet. But out of curiosity I disconnected the wheel speed sensor to see if the computer detected it. Sure enough it did. I *think* that means the wire is functional, as is the sensor itself. Correct me if I'm wrong, but I think that means the magnetic ring on the hub is the problem. I'm posting screenshots of my error codes with the sensor disconnected.
 

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I haven't tried the multimeter yet. But out of curiosity I disconnected the wheel speed sensor to see if the computer detected it. Sure enough it did. I *think* that means the wire is functional, as is the sensor itself. Correct me if I'm wrong, but I think that means the magnetic ring on the hub is the problem. I'm posting screenshots of my error codes with the sensor disconnected.
Not necessarily.

All your sensor-related codes (C1401, C1402, C1406) SPECIFICALLY identify either open-circuit or short-circuit conditions in the wiring to the sensor, or within the sensor itself. The ECU will log these failures even if they are intermittent. Because the insulation on the sensor wiring is elastic, you can get something entangled in the sensor wire enough to stretch it, and break an internal conductor, but as soon as the stress is removed the insulation contracts and brings the ends of the broken wire into contact, and the cable "seems" good, but can be intermittent with suspension movement, vibration, etc.

The magnetic trigger-ring built into the front hub has very few real failure modes; it can either get contaminated with ferrous debris from something else, or the sensor housing can be damaged so that the sensor gets pushed further into its mounting hole and make contact with the magnetic ring, physically damaging it.

But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

From Toyota:
But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

Information from Toyota's 4Runner service documentation:
C1241:
Either condition is met:

1. Both of the following conditions continue for at least 10 seconds:
a) The vehicle speed is more than 3 km/h (2 mph).
b) The IG1 terminal voltage is below 9.5 V.

2. All of the following conditions continue for at least 0.2 seconds:
a) The (brake master cylinder) solenoid relay remains on.
b) The IG1 terminal voltage is below 9.5 V.
c) The relay contact is open.


For the wheel speed sensor codes:

C1401: One of the following conditions is met:

C1402:

1) At a vehicle speed of 10 km/h (6 mph) or more, the output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more.

2) At a vehicle speed of less than 10 km/h (6 mph), the output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more.

3) At a vehicle speed of 10 km/h (6 mph) or more, the outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more.

Areas to inspect:
a) Front speed sensor RH/LH
b) Speed sensor rotor
c) Sensor installation

As for your earlier experience with the magnetic encoder in the wheel hub "going bad", I'm a little skeptical ... what was the specific defect that was found when the hub was removed? Was it actually the wheel bearing(s) that failed?
 

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Discussion Starter #13
Thank you for all the excellent information! I'm reviewing it multiple times to make sure I understand. I will update you as I make progress.

In reference to my previous experience, when I pulled the hub from my old FJ the magnetic ring was in pieces, pretty much gone. The bearings were still completely intact. A friend of mine that has worked on cars for many years helped me pull the hub. He said that's the second time he's seen the magnetic ring get toasted like that. I think it came from me changing the rotors. The front left rotor was incredibly difficult to get off, I had to tap pretty firmly it with a hammer to get it to loosen. I think that's what broke the ring. This time around, I broke a few lug bolts and decided replace all the lugs. I had to go after those with a hammer too, so I'm nervous that the same thing happened.

I could also ask my friend to help me pull the hub again if nothing else works.
As for your earlier experience with the magnetic encoder in the wheel hub "going bad", I'm a little skeptical ... what was the specific defect that was found when the hub was removed? Was it actually the wheel bearing(s) that failed?
 

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Discussion Starter #14 (Edited)
Not necessarily.

All your sensor-related codes (C1401, C1402, C1406) SPECIFICALLY identify either open-circuit or short-circuit conditions in the wiring to the sensor, or within the sensor itself. The ECU will log these failures even if they are intermittent. Because the insulation on the sensor wiring is elastic, you can get something entangled in the sensor wire enough to stretch it, and break an internal conductor, but as soon as the stress is removed the insulation contracts and brings the ends of the broken wire into contact, and the cable "seems" good, but can be intermittent with suspension movement, vibration, etc.

The magnetic trigger-ring built into the front hub has very few real failure modes; it can either get contaminated with ferrous debris from something else, or the sensor housing can be damaged so that the sensor gets pushed further into its mounting hole and make contact with the magnetic ring, physically damaging it.

But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

From Toyota:
But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

Information from Toyota's 4Runner service documentation:
C1241:
Either condition is met:

1. Both of the following conditions continue for at least 10 seconds:
a) The vehicle speed is more than 3 km/h (2 mph).
b) The IG1 terminal voltage is below 9.5 V.

2. All of the following conditions continue for at least 0.2 seconds:
a) The (brake master cylinder) solenoid relay remains on.
b) The IG1 terminal voltage is below 9.5 V.
c) The relay contact is open.


For the wheel speed sensor codes:

C1401: One of the following conditions is met:

C1402:

1) At a vehicle speed of 10 km/h (6 mph) or more, the output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more.

2) At a vehicle speed of less than 10 km/h (6 mph), the output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more.

3) At a vehicle speed of 10 km/h (6 mph) or more, the outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more.

Areas to inspect:
a) Front speed sensor RH/LH
b) Speed sensor rotor
c) Sensor installation

As for your earlier experience with the magnetic encoder in the wheel hub "going bad", I'm a little skeptical ... what was the specific defect that was found when the hub was removed? Was it actually the wheel bearing(s) that failed?
I'm finally getting back to this. In reviewing your comment, I started digging around about the low battery positive voltage code. I went to the dealership and replaced the battery after the CEL and Traction lights initially came on. The battery is new and shouldn't be the issue. So the problem is somewhere after that. How do I find why the skid control ECU isn't getting enough voltage? And why would this suddenly be an issue?
 

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I know it's not recommended but I drive my FJ with both the ABS fuses removed. It's a much safer car.
I've owned three of these vehicles and every one of them has been the same... Prone to activating ABS at low speeds and unnecessarily, and remaining active until you get off, and re-apply the peddle. Dangerous as hell.
Having the first two vehicles checked by Toyota with no problems found, I became very distrustful of the ABS/VSC/TRC system. Then one day when it drifted on, under full brake pressure and almost put me in front of a fast moving Semi-trailer, I decided that i will never install the fuses again. It really is a great car..... without this system..... but a damned scary one with it.
The one i drive now is a 2012 model but friend has a 2013 model. He was descending a long hill (in 4x4 high range) on a good gravel road towing a light trailer and just could not get the vehicle to stop, every application of the brakes resulted in the ABS motor running constantly, giving almost no braking to the vehicle. He left the road on the corner at the bottom of the hill and was able to steer it to safety. In another situation it could doubtless be fatal.
 

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Discussion Starter #17
I know it's not recommended but I drive my FJ with both the ABS fuses removed. It's a much safer car.
I've owned three of these vehicles and every one of them has been the same... Prone to activating ABS at low speeds and unnecessarily, and remaining active until you get off, and re-apply the peddle. Dangerous as hell.
Having the first two vehicles checked by Toyota with no problems found, I became very distrustful of the ABS/VSC/TRC system. Then one day when it drifted on, under full brake pressure and almost put me in front of a fast moving Semi-trailer, I decided that i will never install the fuses again. It really is a great car..... without this system..... but a damned scary one with it.
The one i drive now is a 2012 model but friend has a 2013 model. He was descending a long hill (in 4x4 high range) on a good gravel road towing a light trailer and just could not get the vehicle to stop, every application of the brakes resulted in the ABS motor running constantly, giving almost no braking to the vehicle. He left the road on the corner at the bottom of the hill and was able to steer it to safety. In another situation it could doubtless be fatal.
Damn, that sounds scary as hell. I might consider that as an option. Where are the ABS fuses? Are then in the main fuse box or the Skid Control ECU? I can't find the Skid Control ECU fuse box.
 

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Discussion Starter #18
Not necessarily.

All your sensor-related codes (C1401, C1402, C1406) SPECIFICALLY identify either open-circuit or short-circuit conditions in the wiring to the sensor, or within the sensor itself. The ECU will log these failures even if they are intermittent. Because the insulation on the sensor wiring is elastic, you can get something entangled in the sensor wire enough to stretch it, and break an internal conductor, but as soon as the stress is removed the insulation contracts and brings the ends of the broken wire into contact, and the cable "seems" good, but can be intermittent with suspension movement, vibration, etc.

The magnetic trigger-ring built into the front hub has very few real failure modes; it can either get contaminated with ferrous debris from something else, or the sensor housing can be damaged so that the sensor gets pushed further into its mounting hole and make contact with the magnetic ring, physically damaging it.

But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

From Toyota:
But, before spending any more time troubleshooting the wheel sensor, find out what is triggering the low battery voltage error code. Low battery voltage can cause all kinds of erroneous error codes.

Information from Toyota's 4Runner service documentation:
C1241:
Either condition is met:

1. Both of the following conditions continue for at least 10 seconds:
a) The vehicle speed is more than 3 km/h (2 mph).
b) The IG1 terminal voltage is below 9.5 V.

2. All of the following conditions continue for at least 0.2 seconds:
a) The (brake master cylinder) solenoid relay remains on.
b) The IG1 terminal voltage is below 9.5 V.
c) The relay contact is open.


For the wheel speed sensor codes:

C1401: One of the following conditions is met:

C1402:

1) At a vehicle speed of 10 km/h (6 mph) or more, the output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more.

2) At a vehicle speed of less than 10 km/h (6 mph), the output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more.

3) At a vehicle speed of 10 km/h (6 mph) or more, the outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more.

Areas to inspect:
a) Front speed sensor RH/LH
b) Speed sensor rotor
c) Sensor installation

As for your earlier experience with the magnetic encoder in the wheel hub "going bad", I'm a little skeptical ... what was the specific defect that was found when the hub was removed? Was it actually the wheel bearing(s) that failed?
Quick update. I pulled and cleaned the front right wheel speed sensor. I also checked the voltage/ohms at the wheel and again at the Brake Master Cylinder, both checked out normal. The battery is new, so the voltage there isn't an issue. I'm currently trying to locate the Skid Control ECU box to check those fuses.
 
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