Test B: No Communications With Rear Electronic Module (Rem)

Ensure ignition switch is in LOCK position. Disconnect Rear Electronic Module (REM) harness connectors C420c and C420d. Turn ignition switch to RUN position. Measure voltage between REM 20-pin harness connector C420d terminal No. 3 (Orange/Black wire) and ground. See Fig 1 . If voltage is greater than 10 volts, go to next step. If voltage is less than 10 volts, repair open in Orange/Black wire and retest system operation.
Turn ignition switch to LOCK position. Disconnect REM 22-pin harness connector C420b. Measure resistance between ground and Black wires at REM harness connectors C420c terminals No. 11, 12, 25 and 26. See Fig 2 . Measure resistance between REM 22-pin harness connector C420b terminal No. 12 (Black wire). See Fig 3 . Measure resistance between REM 26-pin harness connector C420c terminal No. 13 (Orange/Black wire) and ground. If resistances are less than 5 ohms, repair module communications concern. See MODULE COMMUNICATIONS NETWORK - LS article. If any resistance is greater than 5 ohms, repair open in appropriate wire and retest system operation.

Fig 1: Identifying Rear Electronic Module (REM) Harness Connector C420d Terminals

Courtesy of FORD MOTOR CO.

Fig 2: Identifying Rear Electronic Module (REM) Harness Connector C420c, Driver's Door Module (DDM) Harness Connector C501d & Front Electronic Module (FEM) Harness Connector C201e Terminals

Courtesy of FORD MOTOR CO.

Fig 3: Identifying Rear Electronic Module (REM) Harness Connector C420b Terminals

Courtesy of FORD MOTOR CO.