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Resistance Test

  1. Using DECODER MODULE TERMINAL RESISTANCE  table below, measure at decoder module connector (with it disconnected). Disconnect negative battery cable. If resistances check good but engine will not crank, replace VATS decoder module. If decoder module is replaced, the existing key code may not match. If they do not match, new keys are needed also.
    DECODER MODULE TERMINAL RESISTANCE (1)

    Measure Between (2) Voltage Specifications
    "T" (YEL) & "U" (BRN) (3) Infinity
    "T" (YEL) & "U" (BRN) (4) 380 to 12.3k
    (1) Decoder module connector & negative battery cable disconnected.
    (2) See Figure & 6 for terminal identification and color.
    (3) Without key in the ignition.
    (4) With key in the ignition.
  2. If resistance between "T" (YEL) and "U" (BRN) without key in ignition is not within specifications, check "T" (YEL) and "U" (BRN) wires for short to ground or between the 2 wires.
  3. If resistance between "T" (YEL) and "U" (BRN) with key in ignition is not within specifications, check "T" (YEL) and "U" (BRN) wires for an open.
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