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Test A: No Communication With DDM

  1. Check Power Supply  - Disconnect DDM 4-pin connector C520 (located in center of driver door). Using a voltmeter, check voltage between ground and DDM 4-pin connector C520 terminal No. 4 (Black/White wire). If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, go to step 4).
  2. Check Black/White Wire For Short To Ground  - Remove circuit breaker No. 7 (20-amp) from engine compartment fuse box located near battery. Using an ohmmeter, check resistance between ground and DDM 4-pin connector C520 terminal No. 4 (Black/White wire). If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Black/White wire and retest system operation.
  3. Check Power To Circuit Breaker No. 7 (20-Amp)  - Using a voltmeter, check voltage between ground and input cavity of engine compartment fuse box circuit breaker No. 7 (20-amp). If voltage is more than 10 volts, repair open in Black/White wire and retest system operation. If voltage is 10 volts or less, repair open power supply to engine compartment fuse box. See POWER DISTRIBUTION section in the WIRING DIAGRAMS article.
  4. Check Yellow/Light Green Wire For Voltage  - Using a voltmeter, check voltage between ground and DDM 4-pin connector C520 terminal No. 3 (Yellow/Light Green wire). If voltage is 10 volts or less, go to next step. If voltage is more than 10 volts, go to step 7).
  5. Check Yellow/Light Green Wire For Short To Ground  - Remove circuit breaker No. 14 (20-amp) from instrument panel fuse block. Using an ohmmeter, check resistance between ground and DDM 4-pin connector C520 terminal No. 3 (Yellow/Light Green wire). If resistance is more than 10 k/ohms, go to next step. If resistance is 10 k/ohms or less, repair short to ground in Yellow/Light Green wire and retest system operation.
  6. Check Power To Circuit Breaker No. 14 (20-Amp)  - Using a voltmeter, check voltage between ground and input cavity of instrument panel fuse block circuit breaker No. 14 (20-amp). If voltage is more than 10 volts, repair open in Yellow/Light Green wire and retest system operation. If voltage is 10 volts or less, repair open power supply to engine compartment fuse box. See POWER DISTRIBUTION section in the WIRING DIAGRAMS article.
  7. Check Black Wires For Open  - Disconnect DDM 18-pin connector C519 (located in center of driver door). Using an ohmmeter, check resistance between ground and DDM 18-pin connector C519 terminals No. 4 and 15. See Fig 1 . If resistances are 5 ohms or more, repair open in appropriate Black wire(s) and retest system operation. If resistances are less than 5 ohms, go to MODULE COMMUNICATIONS NETWORK article to diagnose network concern.
Fig 1: Identifying DDM Connector C519 Terminals
G96I01131Courtesy of FORD MOTOR CO.
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