I got a P0650 but no check engine light

CIRCUIT DESCRIPTION
Ignition voltage is supplied directly to the malfunction indicator lamp (MIL). The power control module (PCM) controls the lamp by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver has a fault line which is monitored by the PCM. When the PCM is commanding a component on, the voltage of the control circuit should be low, near 0 volts. When the PCM is commanding the control circuit to a component off, the voltage potential of the circuit should be high, near battery voltage. If the fault detection circuit senses a voltage other than what is expected, the fault line status will change causing the DTC to set.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC

An improper voltage level has been detected on the MIL control circuit.
The above condition present for at least 30 seconds.

ACTION TAKEN WHEN THE DTC SETS

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

DIAGNOSTIC AIDS
If the ignition feed circuit is suspected of being open, inspect the other bulbs which are powered by the same circuit.

If the condition is intermittent, refer to Intermittent Conditions. See: Powertrain Management Computers and Control Systems Testing and Inspection Initial Inspection and Diagnostic Overview Diagnostic Strategies Intermittent Conditions

TEST DESCRIPTION

Steps 1-10

The numbers below refer to the step numbers on the diagnostic table.

Command both the ON and the OFF states. Repeat the commands as necessary.

If you do not find trouble in the control circuit or the connection at the PCM, the PCM may be faulty. However, this is an extremely unlikely failure.
This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.

That is part of the malfunction light indicator contol light system and that will have to go to a dealership as there may be an ECU problem and there is a special scanner needed to diagnose and reset the cirucuit that only dealerships or Cadillac specialty repair shops will have.