Or If Following Condition Exists:

• Decoder and parity inputs do not agree with possible combinations per BD41 display values found in DATA DISPLAY in introduction portion of this article.

If Code B127 is set, Driver Information Center (DIC) will display warning message GEAR SELECT PROBLEM and IPC PRNDD21 display will flash (digital cluster only).

1. Checks BCM inputs when only decoder "A" and parity circuit are pulled low.
2. Checks BCM inputs when only decoder "B" and "C" inputs are pulled low. This will complete HI/LO check of all 4 BCM inputs.
3. This step checks gear selector switch problem in other gear ranges.
4. Checks to see if code is due to discrepancy between PCM and BCM inputs.
5. Checks for short to ground in gear selector switch to BCM circuits.
6. Checks for open in circuits to BCM.
7. Circuit shorted to ground will result in a "0" for that circuit.
8. Checks for open PRNDD21 sensor ground.
9. Circuit with open will result in a "1" for that circuit.
10. Snap data value of BD41 display will be value BCM recognized when code was set. This is used to determine whether this value is valid. If it is a valid value, PCM park/neutral input must be incorrect to set code.
11. If snap value of BD41 display is invalid, determine which digits are invalid. If all digits read "1", PRNDD21 ground is open. If only one digit is incorrect, that circuit, either in switch or harness, was shorted or open when code was set.