DTC C2121/21: No Signal from Transmitter ID1 in Main Mode; DTC C2122/22: No Signal from Transmitter ID2 in Main Mode; DTC C2123/23: No Signal from Transmitter ID3 in Main Mode; DTC C2124/24: No Signal from Transmitter ID4 in Main Mode; 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): Wiring Diagram