Reminder System Control Unit (MICU, Gauge Control Module) Input Test
MICU
  1. Turn the ignition switch OFF.
  1. Disconnect the under-dash fuse/relay box connectors E, R, S, and T.
    NOTE: All connector views are wire side of female terminals.
  1. Inspect the connector and socket terminals to be sure they are all making good contact.
    • If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system.
    • If the terminals are OK, go to Step 5 .
  1. Reconnect the connectors, then make these input tests at the connector.
    • If any test indicates a problem, find and correct the cause, then recheck the system.
    • If all the input tests prove OK, go to Step 6 .
    Cavity
    Wire
    Test condition
    Test: Desired result
    Possible cause if result is not obtained
    E37
    GRN
    Driver's door open
    Check for voltage to ground: There should be less than 1 V.
    • Faulty driver's door switch
    • An open in the wire
    Driver's door closed
    Check for voltage to ground: There should be 5 V or more.
    • Faulty driver's door switch
    • A short to ground in the wire
    R6
    PNK
    Ignition key inserted into the ignition switch
    Check for voltage to ground: There should be less than 1 V.
    • Poor ground (G403)
    • Faulty ignition key switch
    • An open in the wire
    Ignition switch OFF and ignition key removed from the ignition switch
    Check for voltage to ground: There should be 5 V or more.
    • Faulty ignition key switch
    • A short to ground in the wire
    S1·S5
    RED
    Combination light switch OFF
    Check for voltage between S1 and S5 terminals: There should be less than 1 V.
    • Faulty combination light switch
    • An open in the wire
    Combination light switch in any other position than OFF
    Check for voltage between S1 and S5 terminals: There should be 5 V or more.
    • Faulty combination light switch
    • A short to ground in the wire
    S11·S5
    BRN
    Combination light switch (Headlight position) ON
    Check for voltage between S11 and S5 terminals: There should be less than 1 V.
    • Faulty combination light switch
    • An open in the wire
    Combination light switch OFF
    Check for voltage between S11 and S5 terminals: There should be 5 V or more.
    • Faulty combination light switch
    • A short to ground in the wire
    S13·S5
    GRY
    Combination light switch (SMALL position) ON
    Check for voltage between S13 and S5 terminals: There should be less than 1 V.
    • Faulty combination light switch
    • An open in the wire
    Combination light switch OFF
    Check for voltage between S13 and S5 terminals: There should be 5 V or more.
    • Faulty combination light switch
    • A short to ground in the wire
    T11
    ORN
    passenger's walk-in lever pulled up and hold
    Check for voltage to ground: There should be less than 1 V.
    • Faulty passenger's walk-in switch
    • An open in the wire
    passenger's walk-in lever released
    Check for voltage to ground: There should be 5 V or more.
    • Faulty passenger's walk-in switch
    • A short to ground in the wire
    T12
    GRN
    Driver's walk-in lever pulled up and hold
    Check for voltage to ground: There should be less than 1 V.
    • Faulty driver's walk-in switch
    • An open in the wire
    Driver's walk-in lever released
    Check for voltage to ground: There should be 5 V or more.
    • Faulty driver's walk-in switch
    • A short to ground in the wire

Gauge Control Module (Tach)
  1. Turn the ignition switch OFF.
  1. Disconnect the gauge control module (tach) 36P connector.
  1. Inspect the connector and socket terminals to be sure they are all making good contact.
    • If the terminals are bent, loose or corroded, repair them as necessary, and recheck the system.
    • If the terminals are OK, go to Step 10 .
  1. With the connector still disconnected, make these input tests at the connector.
    • If any test indicates a problem, find and correct the cause, then recheck the system.
    • If all the input tests prove OK, go to Step 11 .
    Cavity
    Wire
    Test condition
    Test: Desired result
    Possible cause if result is not obtained
    16
    BLK
    Under all conditions
    Check for continuity to ground: There should be continuity.
    • Poor ground (G503)
    • An open in the wire
    18
    WHT
    Under all conditions
    Check for voltage to ground: There should be battery voltage.
    • Blown No. 16 (15 A) fuse in the under-hood fuse/relay box
    • An open in the wire
    17
    LT BLU
    Ignition switch ON (II)
    Check for voltage to ground: There should be battery voltage.
    • Blown No. 10 (7.5 A) fuse in the under-dash fuse/relay box
    • An open in the wire

  1. Reconnect the gauge control module (tach) 36P connector, then make these input tests at the connector.
    • If any test indicates a problem, find and correct the cause, then recheck the system.
    • If all the input tests prove OK, go to Step 12 .
    Cavity
    Wire
    Test condition
    Test: Desired result
    Possible cause if result is not obtained
    28
    LT BLU
    Parking brake switch ON (lever pulled)
    Check for voltage to ground: There should be less than 1 V.
    • Faulty parking brake switch
    • An open in the wire
    Parking brake switch OFF (lever pushed)
    Check for voltage to ground: There should be 5 V or more.
    • Faulty parking brake switch
    • A short to ground in the wire

    • If the beeper sounds and the seat belt reminder light flashes, go to Step 13 .
    • If the beeper does not sound or the seat belt reminder light does not flash, replace the gauge control module (tach).
  1. Substitute a known-good gauge control module (tach) and recheck the system.