The last successful reception of telemetry was on April 27, 2002; subsequent signals were barely strong enough to detect. Loss of contact was probably due to a combination of increasing distance and the spacecraft's steadily weakening power source, rather than structural failure of the craft.
The last, very weak signal from Pioneer 10 was received on January 23, 2003, when it was 12 billion kilometers (7.5 billion miles) from Earth.
A contact attempt on February 7, 2003 was not successful.
One final attempt was made on the evening of March 4, 2006, the last time the antenna would be correctly aligned with Earth. No response was received from Pioneer 10.
The spacecraft has operated on a backup transmitter since launch. Instrument power sharing began in February 1985 due to declining generator power output. Science operations and daily telemetry ceased on September 30, 1995 when the RTG power level was insufficient to operate any experiments. As of the end of 1995, when its mission ended, the spacecraft was located at 44.7 AU from the Sun at a nearly asymptotic latitude of 17.4 degrees above the solar equatorial plane and was heading outward at ~2.4 AU/year (11.6 km/s); this is the lowest velocity of the five spacecraft now escaping the Solar System (Voyagers 1 and 2, Pioneers 10 and 11, and New Horizons). 
Earth's motion has carried it out of alignment with the spacecraft antenna. As the antenna cannot be maneuvered to point back at our planet, it is no longer possible with current technology to establish further communication from Earth with the probe.