DTC C2121/21 No Signal from Transmitter ID1; DTC C2122/22 No Signal from Transmitter ID2; DTC C2123/23 No Signal from Transmitter ID3; DTC C2124/24 No Signal from Transmitter ID4; DTC C2125/25 No Signal from Transmitter ID5; DTC C2181/81 Transmitter ID1 not Received (Test Mode DTC); DTC C2182/82 Transmitter ID2 not Received (Test Mode DTC); DTC C2183/83 Transmitter ID3 not Received (Test Mode DTC); DTC C2184/84 Transmitter ID4 not Received (Test Mode DTC); DTC C2185/85 Transmitter ID5 not Received (Test Mode DTC): Wiring Diagram
WARNING: This page is about a different car, the 2008 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.