2004 Tahoe ABS and throttle by wire problems....

Algon

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Hello all, hoping someone here can help me. I have a 2004 Tahoe 2wd. Recently started to get an ABS shudder at low speeds just as it comes to a stop. No ABS or traction control lights on dash and no ABS codes stored. Weird part is after this happens when I go to take off while still in drive there is no throttle response. I mean none like the pedal is not connected. When I pop it in into neutral it revs up fine. Put it back into drive and nothing. Now if I put it in park and then down to drive it will accelerate and moves the vehicle forward one again ...until the next application of brakes when the whole cycle starts again.
I have pulled the ABS 60A fuse to disable the system and the all the problems go away. Truck brakes fine shifts fine and now of course I have ABS and T/C lights on the dash and no ABS.
I am surprised that possible failure/problems in the ABS system can cause a shutdown of the throttle by wire circuit? I have tried replacing both front wheel speed sensors but problem still persists. Anyone ever hear of such a problem? Did a lot of searches before posting this and I could not find anything where ABS and loss of throttle occurred together.
 

Algon

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None. no codes. Of course the fuse is still out so abs and t/c lights are on. Not driveable long enough with the fuse in to get a code stored. Guessing I need to find someone with a Tech II scan tool.
 
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Fless

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You should have codes with those fuses pulled. Perhaps your scanner doesn't read ABS codes?
 

PNWTahoe

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Rear ABS sensors look ok?

Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set.

Cause

The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface.

Correction

Measure AC voltage and clean the wheel speed sensor mounting surfaces.

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual.
2. Disconnect both the front wheel speed sensor connectors at the frame and harness.
3. Place a Digital Volt Meter (DVM) across the terminals of each wheel speed sensor connector.
4. Rotate the wheel clockwise approximately one revolution per second. The minimum reading should be at least 350 ACmV's. If the reading is less than 350 ACmV's, remove the wheel speed sensor. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
5. Plug the wheel speed sensor bore in order to prevent debris from falling into the hub during service.
6. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, scotch brite, or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion.
7. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor.
8. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (in Canada, P/N 89022218).
9. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor O-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (in Canada, P/N 993037).
10. Install either the original sensor or a new one in the hub. Ensure that the sensor is seated flush against the hub. Refer to the applicable Wheel Speed Sensor Replacement procedure in the ABS sub-section of the Service Manual.
11. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel. The voltage should now read at least 350 ACmV's.
 

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