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MSMM System Check

WARNING: This page is about a different car, the 2000 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Do not use test light in following test. Low current voltage will not illuminate test light.
  1. Check IOD fuse (10-amp) in Power Distribution Center (PDC). Replace fuse if faulty or missing. Operate seat switch in all directions. If MSMM internal relay (and seat) does not respond to any switch input, go to next step. If relay does not click for one or more directions, go to step  9 . If relay clicks in all directions, but seat does not respond in one or more directions, go to step  10 .
  2. Check for voltage (backprobe) at 10-pin MSMM connector C2 terminal No. 8 (Red wire). See Figure . Using DVOM connected to battery voltage, check for ground at 10-pin MSMM connector C2 terminal No. 7 (Black wire). See WIRING DIAGRAMS  . If no problem is found, go to next step. If any problem is found, repair as necessary.
  3. Check MSMM connectors for corroded or loose connections. If no problem is found, go to next step. If any problem is found, repair as necessary.
  4. Set parking brake. Place shifter in any position except Park. Check for seat position sense reference voltage (5 volts) at 21-pin MSMM connector C3 terminal No. 20 (Brown/White wire). Check for mirror position sense voltage (5 volts) at 25-pin MSMM connector C1 terminals No. 2 (Yellow/Orange wire), No. 3 (Dark Blue wire), No. 14 (Yellow/Red wire) and No. 15 (Dark Green/Red wire). If no problem is found, go to next step. If any problem is found, repair circuit(s) as necessary.
  5. Remove power seat switch. See REMOVAL & INSTALLATION  . Check seat switch connector terminals for corrosion or poor contact. If no problem is found, go to next step. If any problem is found, repair as necessary.
  6. Using DVOM, check voltage between 21-pin MSMM connector C3 terminal No. 11 (Red wire) and seat switch connector terminal No. 1 (Black wire). If low current voltage exists, go to next step. If low current voltage does not exist, replace MSMM as necessary.
  7. Check voltage between seat switch terminals No. 5 (Red wire) and terminal No. 1 (Black wire). If low current voltage exists, go to next step. If low current voltage does not exist, repair open circuit in Red wire between MSMM and switch.
  8. Using DVOM, check switch output. Operate switch in each direction and check for low current voltage at appropriate seat switch terminal. See CHECKING POWER SEAT CIRCUITS  table for switch position and switch terminal identification. Replace switch if low current voltage does not exist as specified.
  9. Check continuity of inoperative circuit between switch and MSMM. See CHECKING POWER SEAT CIRCUITS  table. If circuit continuity exists, replace MSMM. If circuit continuity does not exist, repair open circuit.
  10. Disconnect 10-pin MSMM connector C2. Connect a jumper wire to harness connector C2 terminal No. 8 (Red wire). Connect another jumper wire to harness connector C2 terminal No. 7 (Black wire). Using jumper wires, apply battery voltage and ground to inoperative motor terminals on harness connector. See CHECKING SEAT MOTOR OPERATION  table. If motor operates, replace MSMM. If motor does not operate, go to next step.
  11. Check wiring between 21-pin MSMM connector C3 and suspect motor connector. See WIRING DIAGRAMS  . Repair wiring as necessary. If wiring is okay, replace track assembly. Individual motors are not replaceable. See REMOVAL & INSTALLATION in POWER SEATS - CARAVAN, TOWN & COUNTRY, & VOYAGER article.
CHECKING POWER SEAT CIRCUITS

Seat Movement Wire Color (1) MSMM/Switch Terminals
Horizontal Forward Yellow/Light Blue 14/6
Horizontal Backward Red/Light Blue 3/3
Front Up Yellow/Light Green 12/7
Front Down Red/Light Green 1/10
Rear Up Yellow/White 13/8
Rear Down Red/White 2/9
Recliner Up Gray/Light Blue 15/2
Recliner Down Gray/White 4/4
(1) 21-pin MSMM connector C3.
CHECKING SEAT MOTOR OPERATION

Seat Movement (1) Apply Battery Voltage/Ground
Horizontal Forward 2/1
Horizontal Backward 1/2
Front Up 5/10
Front Down 10/5
Rear Up 3/6
Rear Down 6/3
Recliner Up 4/9
Recliner Down 9/4
(1) Apply battery positive and negative to 21-pin MSMM connector C3 terminals as listed.
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