KFtransam

So I just got my hands on a 99 Grand Prix. Been driving it for about 3 days now when the SES lamp comes on

I ran up to autozone and had em pull the code.
P0650 - Malfunction Indicator Lamp (MIL) fault

From what I'm reading this is a "your bulb is burnt out" code. When very appperantly my light is lit.

Just curious as to what could be causing the problem.. I did get the car with a poorly wired sound system in the trunk and can link te check engine light directly to my "seeing what this systems got!"

Wondering if lowering the voltage temporarily caused the PCM to read a voltage fault with the MIL, thus throwing a code.

First step is to clear the code (which the parts stores won't do anymore) and see if it comes back. Waiting on my little handheld reader to come in the mail any day now!

Chopstix

iTrader: (1)

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P0650

Description
Malfunction Indicator Lamp (MIL) Control Circuit Output drive moduels (ODM’s) are used by the powertrain control module (PCM) to turn on many of the current-driven devices that are needed to control various engine and transaxle functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device whish the PCM is commanding ON. Unlike quad diver modules (QDM’s) used in prior model years, ODM’s have the capability of diagnosing each output circuit individually. DTC P0650 set indicates an improper voltage level on the output circuit that control the MIL.

Symptoms

The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
The PCM will store the conditions, which were present when the DTC set as Freeze Frame and Failure Records Data only.
If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.
Causes

An improper voltage level has been detected on ODM D output 1 (the MIL control circuit)
The above conditions are present for at least 30 seconds.

Solutions
Check for the following conditions:

A faulty connection at the PCM – inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.
Inspect the wiring harness for damage.
If the harness appears to be okay, disconnect the PCM, turn the ignition ON and observe a DMM connected between the MIL control circuit and ground at the PCM harness connector while moving connectors and wiring harnesses related to the MIL. A change in voltage will indicate the location of the fault.
Located the MIL fuse. If the fuse is open, locate and repair a short to ground in the MIL ignition supply circuit or a shorted cluster. Inspect the MIL fuse and replace as necessary. Did you find and replace the blown fuse and make repairs?
Yes – Clear the DTC.
NO – Turn the ignition OFF and disconnect the PCM. If the jumper fuse opens, locate and repair a short to voltage in the MIL control circuit or a shorted cluster. Install a 3amp fused jumper between the MIL control circuit at the PCM harness connector and a good ground. Turn the ignition ON with the engine off. Is the MIL illuminated?
YES – Leave the ignition on and remove the jumper. Is the MIL still illuminated?
YES – Remove the instrument cluster. Test the MIL control circuit for a short to ground and repair as necessary. Did you fin and repair the condition?
YES – Clear the DTC
NO – Inspect the PCM and PCM harness connector for faulty connections and repair as necessary. Did you find and correct the connection?
YES – Clear DTC
NO – Replace the PCM
NO – Remove the instrument cluster. Test the MIL control circuit for a short to ground and repair as necessary. Did you fin and repair the condition?

YES – Clear the DTC
NO – Test the MIL ignition supply circuit for an open and repair as necessary. Did you find a problem and correct?
YES – Clear the DTC
NO – Inspect the cluster harness connector for faulty connections and repair as necessary. Did you find and repair the condition?
YES – Clear the DTC
NO – Repair or replace the cluster. Did you complete the repair or replacement?
YES – Clear the DTC

KFtransam

Cool, thanks!