Do you know about yaw rate? A lot of people have actually never heard of a yaw rate sensor or what it does. It’s a critical part of the traction or stability control systems in modern vehicles and helps the computer determine if the vehicle is slipping or sliding sideways. Let’s find out how one technician used a code combo to address one customer’s complaint about a traction control and anti-lock brake system light on their 2004 Toyota Sienna XLE 3.3L.
Diagnosis
The technician started by scanning for codes and found C1210 – Zero Point Calibration Undone and C1234 – Yaw Rate Sensor Circuit. Using this info, he used a multi-meter to measure the power and ground of the yaw rate sensor connector. With the key on, he back-probed for 5 Volt supply and less 100mv ground and found both were present. He left the sensor unbolted, held it vertical and back-probed the connector with the multi-meter to measure voltage change when rotating yaw rate sensor by hand.
Again with the key on, he back-probed the connector, but this time terminal two and three. He found the specified 2.5 Volts did not change as the sensor was rotated by hand. Then he did the same, yet he did it with terminals one and two and found the specified 4.5 to 5.5 Volt signal was erratic as the sensor was rotated. Finally, the tech disconnected the connector for the yaw rate sensor, inspected the connector, terminals and wiring harness and found no apparent faults.
Fix
These test results verified the yaw rate sensor was actually at fault. Once the technician replaced the sensor and cleared the codes his customer was able to head home traction control and ABS light free.
Real Fixes from Mitchell 1’s SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read the Real Fix in the Mitchell 1 ShopConnection Blog
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