The GTP and Regal GS (SC only) have the full range traction control system meaning it applies the brakes when a low trac situation develops.
The standard traction control system limits wheelspin by reducing power and upshifting the tranny via the PCM.
Most ABS and traction DTC error codes cannot be read by a basic odb-ii scanner but shops with higher level systems including the dealer with the Tech II machine can read ABS/TRAC codes which are in the CHASSIS code family and manufacturer specific. Higher up scanners like the Actron CP9145, etc. and up will read these codes. ABS codes will tell you which specific wheel sensor is bad, wiring or ABS modules, etc.
I found 99% of ABS/TRAC problems are the wheel sensor in the hub/bearing assembly and/or the wiring leading up to the wheel sensor connector which is routed on the lower control arm.
BTW - The problem sounds like a crankshaft position sensor (CKPS) going bad.
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials