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Test M: No Module/Network Communication - SCP Bus Link

WARNING: This page is about a different car, the 2001 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Depending on module configuration, with all modules connected and with ignition switch in RUN position or with engine running, 2-3 volts may be present at Data Link Connector (DLC) terminals No. 2 (Tan/Orange wire) and No. 10 (Pink/Light Blue wire). These are the Standard Corporate Protocol (SCP) diagnostic communications network circuits.
NOTE: Front radio control unit may also be referred to as Audio Control Module (ACM). Speed control servo may also be referred to as Next Generation Speed Control (NGSC) servo. Air Suspension/Electronic Variable Orifice (EVO) steering module may also be referred to as Rear Air Suspension Module (RASM). Instrument cluster may also be referred to as Hybrid Electronic Cluster (HEC).
  1. Turn ignition switch to LOCK position. Inspect New Generation Star (NGS) tester connector for loose, damaged or corroded terminals. Repair connector as necessary and test system for normal operation. If connector is okay, go to next step.
  2. Ensure ignition switch is in LOCK position. Inspect Data Link Connector (DLC) for physical damage, bent terminals or corrosion. DLC is located below left side of instrument panel, to right of steering column. Repair connector as necessary and test system for normal operation. If connector is okay, go to next step.
  3. Turn ignition switch to LOCK position. Disconnect speed control servo 10-pin harness connector. Speed control servo is located at left rear corner of engine compartment. Figure. Measure resistance in Tan/Orange wire between speed control servo harness connector terminal No. 1 and DLC terminal No. 2. See Figure and Figure . Measure resistance in Pink/Light Blue wire between speed control servo harness connector and DLC terminal No. 10. If both resistance readings are less than 5 ohms, go to next step. If either resistance reading is 5 ohms or more, repair open in Tan/Orange wire and/or Pink/Light Blue wire between in-line harness connector C201 and DLC. In-line harness connector C201 is located behind left side of instrument panel. See Figure. Restore harness connections and test system for normal operation.
  4. Connect NGS tester to DLC. Turn ignition switch to RUN position and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than speed control servo did not pass data link diagnostic test, go to next step. If all modules equipped on vehicle passed data link diagnostic test, except speed control servo, replace speed control servo. Restore harness connections and test system for normal operation.
  5. Turn ignition switch to LOCK position. Disconnect 76-pin in-line harness connector C201. In-line harness connector C201 is located behind left side of instrument panel. See Figure. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If all modules equipped on vehicle except Powertrain Control Module (PCM), Anti-lock Brake System (ABS) module and speed control servo passed data link diagnostic test, reconnect in-line harness connector C201 and go to next step. If any module other than PCM, ABS module and speed control servo did not pass data link diagnostic test, reconnect in-line harness connector C201 and go to step  8.
  6. Turn ignition switch to LOCK position. Disconnect ABS module harness connector. ABS module is located at right front of engine compartment, under upper radiator support. See Figure. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than ABS module and speed control servo did not pass data link diagnostic test, go to next step. If all modules equipped on vehicle except ABS module and speed control servo passed data link diagnostic test, replace ABS module. Restore harness connections and test system for normal operation.
  7. Turn ignition switch to LOCK position. Disconnect PCM harness connector. PCM is located in engine compartment on left side of firewall. See Figure. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If all modules equipped on vehicle except ABS module, PCM and speed control servo passed data link diagnostic test, replace PCM and test system for normal operation. If any module other than ABS module, PCM and speed control servo did not pass data link diagnostic test, repair circuit No. 914 (Tan/Orange wire) and/or circuit No. 915 (Pink/Light Blue wire) between in-line harness connector C201 and ABS module, PCM, speed control servo and EVAC and fill harness connector C133 (Tan/Orange wire only). EVAC and fill harness connector is located on left fender well. See Figure. Restore harness connections and test system for normal operation.
  8. Turn ignition switch to LOCK position. Disconnect 42-pin in-line harness connector C202. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If all modules equipped on vehicle except Air Suspension/Electronic Variable Orifice (EVO) steering module, Driver's Door Module (DDM) and Driver's Seat Module (DSM) (if equipped) passed data link diagnostic test, reconnect in-line harness connector C202 and go to next step. If any module other than air suspension/EVO steering module, DDM and DSM (if equipped) did not pass data link diagnostic test, reconnect in-line harness connector C202 and go to step  12.
  9. Turn ignition switch to LOCK position. Disconnect DDM harness connector C520. DDM is located inside driver's door. Turn ignition switch to RUN position and perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than DDM did not pass data link diagnostic test, if equipped with a DSM go to next step, or if not equipped with a DSM go to step  11. If all modules on vehicle except DDM passed data link diagnostic test, replace DDM. Restore harness connections and test system for normal operation.
  10. Turn ignition switch to LOCK position. Disconnect DSM harness connector C313. DSM is located under driver's seat. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than DSM and DDM did not pass data link diagnostic test, go to next step. If all modules on vehicle except DSM and DDM passed data link diagnostic test, replace DSM. Restore harness connections and test system for normal operation.
  11. Disconnect air suspension/EVO steering module Black harness connector C251. Air suspension/EVO is located behind instrument panel next to glove box and is mounted on tunnel. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If all modules equipped on vehicle except DSM, DDM and air suspension/EVO steering module passed data link diagnostic test, replace air suspension/EVO steering module. Restore harness connections and test system for normal operation. If any module other than DSM, DDM and air suspension/EVO steering module did not pass data link diagnostic test, repair circuit No. 914 (Tan/Orange wire) and/or circuit No. 915 (Pink/Light Blue wire) between in-line harness connector C202 and DSM (if equipped), DDM and air suspension/EVO steering module. Restore harness connections and test system for normal operation.
  12. Turn ignition switch to LOCK position. Disconnect Lighting Control Module (LCM) 16-pin harness connector C221. LCM is located under center of instrument panel, to right of steering column. See Figure. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than LCM did not pass data link diagnostic test, if equipped with front radio control unit go to next step, or if not equipped with front radio control unit go to step  14. If all modules equipped on vehicle except LCM passed data link diagnostic test, replace LCM. Retest system for normal operation.
  13. Turn ignition switch to LOCK position. Disconnect front radio control unit 20-pin harness connector C258. Front radio control module is located behind center of instrument panel, on radio. See Figure. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than LCM and front radio control unit did not pass data link diagnostic test, go to next step. If all modules equipped on vehicle except LCM and front radio control unit passed data link diagnostic test, replace front radio control unit. Retest system for normal operation.
    14. NOTE: Instrument cluster harness connector C254 can be identified by observing that pin cavities No. 16 and 19 are vacant.
  14. Turn ignition switch to LOCK position. Disconnect instrument cluster 12-pin harness connector C254. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If any module other than instrument cluster, LCM and front radio control unit (if equipped) did not pass data link diagnostic test, go to next step. If all modules equipped on vehicle except instrument cluster, LCM and front radio control unit (if equipped) passed data link diagnostic test, replace instrument cluster. Retest system for normal operation.
  15. Turn ignition switch to LOCK position. Disconnect Electronic Automatic Temperature Control (EATC) module White harness connector C281. EATC module is located in center of instrument panel. Figure. Turn ignition switch to RUN position. Using NGS tester perform data link diagnostic test. See DATA LINK DIAGNOSTIC TEST  under SELF-DIAGNOSTIC SYSTEM. If all modules equipped on vehicle except EATC, instrument cluster, LCM and front radio control unit (if equipped) passed data link diagnostic test, replace EATC module and test system for normal operation. If any module other than EATC module, instrument cluster, LCM and front radio control unit (if equipped) did not pass data link diagnostic test, repair circuit No. 914 (Tan/Orange wire) and/or circuit No. 915 (Pink/Light Blue wire) between in-line harness connector C202 and LCM, front radio control unit (if equipped), instrument cluster and EATC module. Restore harness connections and test system for normal operation.
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