DTC U1128: Loss Of Serial Communications - IRC: Testing
- Using scan tool, verify that communication can be established with radio receiver. Operate radio to ensure that entertainment system is powered properly. If radio system is powered properly, go to next step. If radio system is not powered properly, repair as necessary and go to step 6).
- Turn ignition switch to OFF position. Disconnect radio receiver. Check for poor connection at radio receiver terminal F6 (Brown/White wire). Repair as necessary and go to step 6). If connection is okay, go to next step.
- Using DVOM, check resistance of Brown/White wire between radio receiver terminal F6 and Data Link Connector (DLC) terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, go to step 5)
- Replace and program radio receiver. See PROGRAMMING . Go to step 6).
- Repair open in Brown/White wire between radio and DLC. Go to next step.
- Turn ignition switch to ON position. Check for loss of class 2 communication codes (U1000 through U1255) in radio receiver and BCM. Clear codes from both components. Recheck system operation.