DTC P1669: Abs Unit Expected: Description

The Electronic Brake and Traction Control Module (EBTCM) sends torque reduction request information to the ECM over Orange/Black wire. This information is needed by the ECM to reduce engine power via spark retard or injector disable (in extreme cases) during a traction control event. The torque reduction request signal is a 0 to 12 volt pulse width modulated square wave created by the EBTCM grounding Orange/Black wire. The signal circuit is pulled up to 12 volts in both the ECM and EBTCM. The EBTCM continuously pulse width modules the signal over Orange/Black wire, even if no traction control event is present. This is to allow the ECM to detect a fault in the torque reduction request circuit. DTC P1669 will set if the ECM does not receive a signal from the EBTCM over the torque reduction request circuit with the engine running when the ECM has the anti-lock brake option programmed.