Possible Causes

WARNING: This page is about a different car, the 2002 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.

TR switch fault.
TR switch misadjustment.
Short to ground between TR switch terminal "A" and TCM terminal 2B.
Short to ground between TR switch terminal "E" and TCM terminal 1W.
Short to ground between TR switch terminal "D" and TCM terminal 1T.
Short to ground between TR switch terminal "G" and TCM terminal 1Z.
Short to ground between TR switch terminal "I" and TCM terminal 1AA.
Short to ground between TR switch terminal "F" and TCM terminal 2C.
Open circuit between TR switch terminal "A" and TCM terminal 2B.
Open circuit between TR switch terminal "E" and TCM terminal 1W.
Open circuit between TR switch terminal "D" and TCM terminal 1T.
Open circuit between TR switch terminal "G" and TCM terminal 1Z.
Open circuit between TR switch terminal "I" and TCM terminal 1AA.
Open circuit between TR switch terminal "F" and TCM terminal 2C.
Open circuit between TR switch terminal "C" and IG key (ACC).
Short to ground between TR switch terminal "C" and IG key (ACC).
Damaged connector or wiring harness between TR switch and TCM.
TCM fault.