No Response From Radio
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
- Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, attempt to communicate with Body Control Module (BCM). If scan tool communicates with BCM, go to next step. If scan tool does not communicate with BCM, repair communication concern. See NO RESPONSE FROM BODY CONTROL MODULE (BUS +/- SIGNAL OPEN) .
- Turn ignition off. Remove and inspect fuse No. 4 (10-amp) in junction block. If fuse is okay, go to next step. If fuse is blown, go to step 9 .
- Install fuse No. 4. Disconnect radio harness connector C2. Turn ignition on. Measure voltage at terminal No. 6 (Red wire) radio harness connector C2. See Fig 1 . If battery voltage exists, go to next step. If battery voltage does not exist, repair power distribution circuit as necessary. See POWER DISTRIBUTION article in WIRING DIAGRAMS.
- Turn ignition off. Measure voltage at terminal No. 7 (Pink wire) at radio harness connector C2. If battery voltage exists, go to next step. If battery voltage does not exist, repair power distribution circuit as necessary. See POWER DISTRIBUTION article in WIRING DIAGRAMS.
- Ensure radio ground circuit and antenna are correctly installed. If problem does not exist, go to next step. If problem exists, repair as necessary.
- Disconnect radio harness connector C3. Connect Diagnostic Readout Box (DRBIII(R)) to Data Link Connector (DLC). Connect Scope Input Cable (CH7058) to channel one connector on DRBIII(R). Connect Red and Black leads and Cable Probe Adapter (CH7062) to scope input cable. Using DRBIII(R), access lab scope 12-volt square wave and set to 20-volt range. Go to next step.
- Connect Black lead to ground and Red lead to terminal No. 1 (Violet/Yellow wire) at radio harness connector C3. Turn ignition on. If voltage does not pulse from zero to 7.5 volts, go to next step. If voltage pluses from zero to 7.5 volts, replace radio.
- Turn ignition off. Disconnect Body Control Module (BCM) harness connector C1. Measure resistance in Violet/Yellow wire between terminal No. 1 at radio harness connector C3 and terminal No. 5 at BCM harness connector C1. See Figure and Fig 1 . If resistance is greater than 5 ohms, repair open in Violet/Yellow wire between radio module and BCM. If resistance is 5 ohms or less, replace BCM.
- Disconnect radio harness connector C2. Measure resistance between ground and output side of fuse No. 4 in junction block. If resistance is greater than 100 ohms, go to next step. If resistance is 100 ohms or less, repair short to ground in power distribution circuit as necessary. See POWER DISTRIBUTION article in WIRING DIAGRAMS.
- Connect all disconnected connectors. Install fuse No. 4. Operate radio. If fuse blows, replace radio. If fuse does not blow, problem is intermittent.