2006 4wd trac issue

[mangosmoothie]

I'm having a problem on my 2006 SR5 4wd.

The issue is only happening in 4wd. In 4hi, when taking off from a stop (even on dry asphalt at a normal takeoff speed) the slip light flashes and power is cut for a brief moment. In 4lo, trac actuates when taking off and I can hear the abs pump going off. It's a pretty bad noise. If I unplug the master level sensor, the issue stops. However, I'd like trac working for off road. I don't think it's VSC because there is no buzzer.

I have removed all 4 wheel speed sensors, cleaned the tips, blown out the tone ring area with compressed air. I verified all sensors are reading (they are) and agree on speed (they do when going straight, slight difference when turning obviously)

I've tried a zero point cal of the yaw/decel/master cyl pressure by using my scanner, and again with the paperclip method.

There are no powertrain or chassis codes.

The yaw/decel sensor appears to be working as it should, no crazy readings.

Does anyone have any idea what it may be?

 

[Jermc]

It will likely be the same as mine, there will have been water intrusion into your front wheel hubs where the ABS sensor is, causing rust which then sticks to the sensor. You can take the sensor out and clean it, but it will likely come back right away. The long term fix is to get your front wheel bearings and seals replaced.

 

[mangosmoothie]

I got it! I used a scanner and crawled forward in 4lo. I noticed the right front sensor was not registering until 5 kmh, all the rest would register at 1 kmh.

What you describe above was, what I believe, the original problem. The left front sensor picked up a lot of rust flakes and skewed the reading. A ton of brake clean and compressed air later, I got the bore clean. Just for good measure I pulled the other 3 sensors and cleaned them, but didn't really find any debris. I kept checking that left front and it stayed clean.

However, on reassembly I botched the right front. The sensor o ring got pinched at 12 the oclock position and the sensor wasn't fully seated in the bore. I wasn't able to tell until I pulled the wheel off.

Now everything is working great, I must have gotten the left front clean because I still don't see any rust flakes like I did before.

I definitely agree a new wheel bearing and dust seals are in order for a permanent long term fix, the rust came from somewhere.