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Technical Description of OBD-II Trouble Code
Control Circuit for Malfunction Indicator Lamp (MIL)
What does that signify?
This code is a generic powertrain code that applies to all makes and models of vehicles (1996-newer). However, the specific repair steps may vary slightly depending on the model.
This diagnostic trouble code (DTC) is triggered when the vehicle’s Powertrain Control Module detects a fault with the electrical circuit of the Malfunction Indicator Lamp (MIL).
The Malfunction Indicator Lamp (MIL) is commonly known as the “Check Engine Light” or “Service Engine Soon” light. Although many refer to it as the Check Engine Light, the correct term is MIL. In some vehicles, the PCM detects either too high or too low voltage, or no voltage at all, through the M.I. lamp. The PCM controls the lamp by monitoring its ground circuit and checking the voltage on that circuit.
Note: When the ignition is turned on or the car is started, it is normal for the malfunction indicator lamp to illuminate for a few seconds and then turn off.
Symptoms
The symptoms of a P0650 DTC may include:
Causes
Possible causes may include:
Diagnostic Steps & Possible Solutions
The first thing to check is whether the bulb comes on when it’s supposed to. It should come on for a few seconds when the ignition is turned on. If the light turns on for a few seconds and then goes off, it indicates that the bulb/LED is functioning properly. If the lamp turns on and remains on, it also indicates that the bulb/LED is functioning properly.
If the malfunction indicator lamp does not come on at all, you need to diagnose where the problem lies. If you have access to an advanced scan tool, you can use it to command the MIL to turn on and off. Verify its operation that way.
Physically check if the bulb is burned out and replace it if necessary. Also, inspect to ensure that the bulb is properly seated and making a good electrical connection. Visually inspect all the wiring and connectors leading from the M.I. lamp to the PCM. Inspect the wires for any chafed insulation, etc. Separate all connectors as necessary to inspect for bent pins, corrosion, broken terminals, etc. Clean or repair as needed. You will need a vehicle-specific repair manual to identify the correct wires and harnesses.
Check if other components in the instrument cluster are functioning properly. This includes other warning lamps, gauges, etc. Note that you may need to remove the cluster during the diagnostic steps.
If your vehicle is equipped with a PCM or MIL fuse, check it and replace it if necessary. If everything checked thus far appears to be in order, use a digital volt ohm meter (DVOM) to probe the appropriate wires in the circuit at the lamp end and the PCM end to verify proper operation. Check for shorts to ground or an open circuit.
If everything checks out according to the manufacturer’s specifications, replace the PCM as it may have an internal fault. Replacing the PCM should be a last resort and requires the use of specialized equipment for programming. Consult a qualified technician for assistance.
Professional Service
While we always recommend seeking mechanical solutions for this issue, if it is not feasible, we offer the option to permanently delete this specific DTC. All other codes will continue to function. If you are interested in this option, please upload your ECU file to our portal.
