P0650 Malfunction Indicator Lamp (MIL) Control Circuit Malfunction Trouble Code

P0650 Malfunction Indicator Lamp (MIL) Control Circuit

OBD-II Trouble Code Technical Description

Malfunction Indicator Lamp (MIL) Control Circuit

What does that mean?

This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model.

This diagnostic trouble code (DTC) is set when the vehicle's Powertrain Control Module detects a fault with the Malfunction Indicator Lamp (MIL) electrical circuit.

 

The MIL is commonly referred to as the "Check Engine Light" or "Service Engine Soon" light. MIL is the correct term, however. Basically what happens on some vehicles is the vehicles' PCM senses too high or low, or no voltage present through the M.I. lamp. The PCM controls the lamp by monitoring the ground circuit of the lamp and checks the voltage on that ground circuit.

Note: It is normal operation for the malfunction indicator lamp to illuminate for a few seconds and then go out when the ignition is turned on or the car is started.

Symptoms

Symptoms of a P0650 DTC may include:

Malfunction indicator lamp NOT illuminating when it should (check engine light or service engine soon light) MIL being illuminated all the time

Causes

Potential causes may include:

Burned out MIL bulb/LED MIL wiring problem (short or open electrical condition) Poor electrical connection at the bulb/cluster/PCM Failed/faulty PCM

Diagnostic Steps & Possible Solutions

First thing to check is whether the bulb comes on when it's supposed to. It's supposed to 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, you know the bulb/LED is good. If the lamp turns on and stays on you also know the bulb/LED is good.

If the MIL 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 on and off. Verify operation that way.

Physically check if the bulb is burned out. Replace if it is. Also, inspect to make sure the bulb is seated properly and making a good electrical connection. Visually inspect all the wiring & connectors leading from the M.I. lamp to the PCM. Inspect the wires for chafed insulation, etc. Separate all connectors as required to inspect for bent pins, corrosion, broken terminals, etc. Clean or repair as required. You will need access to a vehicle specific repair manual to identify the correct wires and harnesses.

Check if other things in the instrument cluster are working properly. 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, replace as necessary. If everything thus far checks out, you should use a digital volt ohm meter (DVOM) to probe the appropriate wires in the circuit at the lamp end and the PCM end, verify proper operation. Check for shorts to ground, or an open circuit.

If everything checks out against manufacturers specifications, replace the PCM, it could be an internal fault. Replacing the PCM is the last resort and requires the use of specialized equipment to program it, consult a qualified technician to assist.

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