2009 Chevrolet Impala - Answered Questions & Fixed issues
09 impala engine runs with key off
First off you need to read how this works . BCM - body control module is in fail- safe mode more then likely . The ingition switch is a input to the BCM . The BCM turns on relays to turn vehicle systems on . If something happens the system will fail safe to last commands by the BCM .
The body control system consists of the body control module (BCM), communications, and various input and outputs. Some inputs, outputs and messages require other modules to interact with the BCM. The BCM also has discrete input and output terminals to control the vehicle's body functions. Battery positive voltage is provided to the BCM from the BCM fuse in the underhood fuse block. The module has two grounds at G 202 as well as one directly to the vehicle battery. The BCM is wired to the GMLAN High speed serial data buss and the GMLAN Low speed serial data buss and acts as a gateway between them. If the BCM does not communicate the vehicle will not start due to the inability of the engine/powertrain control module (ECM/PCM) and vehicle theft deterrent (VTD) control module to communicate without the BCM providing the gateway function.
Power Mode Master
This vehicle body control module (BCM) functions as the power mode master (PMM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determination the power mode that will be sent over the serial data circuits to the other modules that need this information, and so the PMM will activate relays and other direct outputs of the PMM as needed. Refer to Power Mode Description and Operation for a complete description of power mode functions.
Relay Controlled Power Mode
The body control module (BCM) uses the discrete ignition switch inputs Off/Run/Crank Voltage, Accessory Voltage, and Ignition 1 Voltage, to distinguish the correct power mode. The BCM, after determining the desired power mode, will activate the appropriate relays for that power mode.
The RAP relay remains on for a timed period after the Ignition key is removed. Refer to Retained Accessory Power Description and Operation for more information on the retained accessory power (RAP) function.
You mite want to thing about taking your vehicle to a qualified repair shop. Hooking up a professional or factory scanner to view input data to the BCM ,plus checking for DTC'S - diagnostic trouble codes in the BCM , autozone , advance part stores can not read codes in the BCM .
2009 Chevy impala overheating even after putting coolant
First of all, Alysa, that's not nearly enough information. The most common causes of engine overheating are: leaking hoses, radiator leaks, heater core leaks, a failed water pump, thermostat leak, freeze plugs leak, automatic transmission oil cooler leak and (I hope not for your sake) a cracked block or cylinder heads. Make sure you have the radiator filled with the proper amount and ratio of water and anti-freeze. Simply dumping more anti-freeze in there won't help. Check for leaks and check the thermostat before doing anything. Hope this helps. . .
Have 2009 impala ltz shuts down going down road pull over have power but starter won't engage
The starter is computer controlled by way of a relay ! When you turn the key to the start position a low voltage signal is send to the BCM - body control module , the BCM then sends a message over the GMLAN serial data network to the PCM for starter engagement , The PCM energizes the starter relay sending B+ voltage to the starter solenoid ,if there are no anti-theft system problems. The codes you have listed are emission related codes !
DTC P0455: Evaporative Emission (EVAP) System Large Leak
You must mean P0442 , because there isn't a code P0422 .
DTC P0442: Evaporative Emissions (EVAP) System Small Leak Detected
None of these would cause vehicle to shut down > Your best bet would be to take your vehicle to qualified repair shop an have diagnostics run on it .
No power but stays running
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