My 2009 dts Cadillac started yesterday but this morning went out to start it it wouldn't start lights on in and out just won't turn over
Is there a security light lit on the instrument cluster ? could be a anti-theft system problem ! Three electronic control modules involved in the starting circuit of this vehicle , BCM - body control module , PCM -powertrain control module , an theft deterrent module !
The immobilizer system functions are provided by the theft deterrent module (TDM) and the engine control module (ECM). When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coil surrounding the ignition lock cylinder. This exciter coil is part of the TDM. The energized transponder transmits a signal that contains its unique value, which is received by the TDM. The TDM then compares this value to a value stored in memory. If the values match, the TDM will send the prerelease password via the serial data circuit to the ECM. If the transponders unique value is incorrect, the TDM will send the fuel disable password to the ECM.
When the ignition switch is placed in the Start position a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of the starter relay. When this occurs battery positive voltage is supplied through the switch side of the starter relay to the starter solenoid.
If you knew how , in the under hood fuse / relay box is the
starter relay , it has a four pin socket when relay is removed ! Two should have battery voltage , one should show ground an one is control voltage from the PCM on pin 86 , pin 85 goes to ground. Pin . Pin 87 should have battery voltage an pin 30 supply's voltage to Fuse #24 marked STRTR in the under hood fuse / relay box ! Yea , if you look on the bottom or side of the relay the pins are marked ! Check for what is missing power or control an go from there .
on Mar 25, 2015