FixVault
Home › Lincoln › 1998 › Town Car Base › Repair and Diagnosis › Body & Frame › Door Locks › Anti-Theft Systems - Passive › System Testing › Test A: No Communication With HEC Module

Test A: No Communication With HEC Module

  1. Check For Voltage To HEC  - Turn ignition off. Disconnect HEC (instrument cluster) 12-pin connector C255 (located behind left side of instrument cluster). Turn ignition switch to RUN position. Using voltmeter, check voltage between ground and HEC (instrument cluster) 12-pin connector C255, terminal No. 9 (Gray/Yellow wire). See Figure . If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, go to step 3).
  2. Check Pink/Orange Wire For Open  - Ensure ignition is off. Using an ohmmeter, check resistance between ground and HEC (instrument cluster) 12-pin connector C255, terminal No. 10 (Pink/Orange wire). See Figure . If resistance is less than 5 ohms, see MODULE COMMUNICATIONS NETWORK article to continue diagnosis. If resistance is 5 ohms or more, repair open in Pink/Orange wire between HEC (instrument cluster) and ground.
  3. Check Fuse  - Turn ignition off. Check instrument panel fuse block fuse No. 4 (7.5-amp). If fuse is okay, go to next step. If fuse is not okay, go to step 5).
  4. Check For Power To Fuse  - Turn ignition switch to RUN position. Using a voltmeter, check voltage between ground and input side (bottom terminal) of instrument panel fuse No. 4 (7.5-amp). If voltage is more than 10 volts, repair open in Gray/Yellow wire between instrument panel fuse block fuse No. 4 (7.5-amp) and instrument cluster. Repeat DATA LINK DIAGNOSTIC TEST. If voltage is 10 volts or less, repair Pink/Black wire between instrument panel fuse block and ignition switch. Repeat DATA LINK DIAGNOSTIC TEST.
  5. Check Gray/Yellow Wire For Short To Ground  - Using an ohmmeter, check resistance between ground and HEC (instrument cluster) 12-pin connector C255, terminal No. 9 (Gray/Yellow wire). See Figure . If resistance is less than 10 k/ohms, repair short to ground in Gray/Yellow wire between instrument panel fuse block fuse No. 4 (7.5-amp) and instrument cluster. Repeat DATA LINK DIAGNOSTIC TEST. If resistance is 10 k/ohms or more, replace instrument panel fuse block fuse No. 4 (7.5-amp). Repeat DATA LINK DIAGNOSTIC TEST. If fuse fails again, replace HEC (instrument cluster) and retest system operation.
About FixVault