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Test A: Cannot Communicate With Gem

  1. Check the connections for damage, loose fits, or incorrect installation. Check for loose or damaged wires. Are the connections and wiring okay? If yes, go to next step. If no, repair connectors or wiring as needed. Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  2. Remove and check the power distribution box maxi fuse B. Is the fuse open? If yes, repair circuit 1052 (Tan/Black wire). See WIRING DIAGRAMS . Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
  3. Remove and check the I/P fuse panel fuse 25. Is the fuse open? If yes, go to next step. If no, see step  6.
  4. Disconnect the GEM connector C4. Check the GEM connector terminal No. C4-5 and C4-11 for loose terminals or backed-out pins. Is the connector okay? If yes, go to next step. If no, repair the terminal(s) or install a new harness as needed. See WIRING DIAGRAMS . Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  5. Using DVOM, measure the resistance between the GEM connector terminal No. C4-5 (White/Yellow wire) and ground, and between the GEM connector Terminal No. C4-11 (White/Yellow wire) and ground. Are the resistances greater than 10,000 ohms? If yes, install a new GEM. See GENERIC ELECTRONIC CONTROL MODULE (GEM), CENTRAL TIMER MODULE (CTM)  under REMOVAL & INSTALLATION. Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM. If no, repair the White/Yellow wire. See WIRING DIAGRAMS . Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  6. Install the power distribution box fuse B. Install the I/P fuse panel fuse 25. Disconnect the GEM connector C-4. Measure the voltage between the GEM connector Terminal No. C4-5 (White/Yellow wire) and ground, and between C4-11 (White/Yellow wire) and ground. Are the voltages greater than 10 volts? If yes, go to next step. If no, repair the White/Yellow wire or the Tan/Black wire. See WIRING DIAGRAMS . Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  7. Measure the resistance between the GEM connector Terminal No. C4-18, circuit 57 (Black wire) and ground. Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the Black wire. See WIRING DIAGRAMS . Repeat the self-test. ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  8. Disconnect the GEM connector C1. Using a DVOM, measure the resistance between the GEM connector Terminal No. C1-14 (Black/White wire) and ground, and between C1-26 (Black/White wire) and ground. Are the resistances less than 5 ohms? If yes, go to next step. If no, repair the Black/White wire. See WIRING DIAGRAMS . Repeat the self-test. ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  9. Disconnect the GEM connector C1. Measure the resistance between the GEM connector Terminal No. C1-25 (Light Blue/White wire) and the data link connector (DLC) Terminal No. 7 (Light Blue/White wire). Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the Light Blue/White wire. See WIRING DIAGRAMS . Repeat the self-test. ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  10. Using a DVOM, measure the resistance between the GEM connector Terminal No. C1-25 and ground. Is the resistance greater than 10,000 ohms? If yes, go to next step. If no, the Light Blue/White wire. See WIRING DIAGRAMS . Repeat the self-test. ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
  11. Measure the voltage between the GEM connector Terminal No. C1-25 and ground. Is voltage present? If yes, repair the Light Blue/White wire. Repeat the self-test. If no, install a new GEM. Repeat the self-test. See ON-DEMAND SELF TEST (GEM)  or ON-DEMAND SELF TEST (CTM)  under SELF-DIAGNOSTIC SYSTEM.
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