One problem related to speed sensor has been reported for the 2004 Toyota 4Runner. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2004 Toyota 4Runner based on all problems reported for the 2004 4Runner.
The frame has so much rust on it and other areas of the undercargo that it has caused my speed and abs sensors to work improperly. Speedometer will just quit working and abs lights will come on with the vcs trac, vcs off, and abs lights all coming on, then the engine light will also come on from time to time. There is already a hole rusted through the frame and mechanic said it was just a matter of time before it rusted through and broke.