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2003 Chevrolet Malibu - Page 3 Questions & Answers
Chevy Malibu Cold Idle Problem
Check the water coolant thermostat. If it is stuck in the "open" position you are heating up all the water in the coolant system and this will take time. The thermostat keeps the water in the engine until warmed up to almost normal running temperature, only then does it allow the coolant to enter the radiator.
Most of the warning lights and fuel gauge does not operate when the ignition switch is turned to on.
Given the complexity of your vehicle , all the control modules , serial data communication network. Having the vehicle scanned for DTC'S - diagnostic trouble codes , not a code reader or at a auto parts store . A professional type tool is need to pull codes from BCM - body computer , Instrument cluster .
Fuel Gage
The IPC displays the fuel level as determined by the PCM. The body control module (BCM) receives a class 2 message from the PCM indicating the fuel level percent. The BCM converts the fuel level percent into a percent gage deflection. The IPC receives a message from the BCM via the serial peripheral interface (SPI) indicating the requested gage position. The fuel gage defaults to E (empty) if:
• The PCM detects a malfunction in the fuel level sensor circuit.
• The BCM detects a loss of class 2 communications with the PCM.
• The IPC detects a loss of SPI communications with the BCM.
When the fuel level is less than a pre-determined value, the low fuel indicator illuminates.
Could have U- codes , communication network problems .
DTC U1000 and U1255
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the ID number of the module which sent the message for State of Health monitoring, Node Alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an ID number with at least one critical parameter within about 5.5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. When more than one critical parameter does not have an ID number associated with it, the DTC will only be reported once.
The table below list the modules on the Class 2 Serial Data Circuit that will set a U1000 or U1255 and should be actively communicating the previously described messages on the Class 2 Serial Data Circuit.
I have a 2003 Malibu, 3.1 V6, 120K miles. Normally when I turn the ignition switch to on, all indicator warning lights and gas gauge work in the ip cluster. After a few seconds only the battery, check
Well Gary , you should have it checked for DTC'S - diagnostic trouble codes . Not at a part's store , thier diagnostic tool only checks engine computer codes ! Your vehicle has a number of control modules , PCM/ECM - engine , BCM - body , ABS , Air bag , the instrument cluster has a microprocessor inside , an can set DTC'S as well. But the only way to read codes in most of these modules is with a professional type scan tool . The warning lights come on when you turn the key on as a bulb check an to let you know those systems are functioning . Could be your instrument cluster is defective or a communication network problem , do you know what a serial data bus or communication network is ? This is what the control modules share information on . Your 03 chevy has the IPC bus for data transfer from the BCM to the IPC . U codes are communication error codes .
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
U2000
The IPC determines that the BCM transmitted data to the IPC is invalid for greater than 12 seconds. The IPC sends a message to the BCM via the SPI serial data in circuit indicating that invalid data was received.
U2001
The BCM determines that the IPC transmitted data to the BCM is invalid for greater than 5 seconds.
U2002
The BCM detects that the SPI serial data in circuit is less than 1.2 v for greater than 5 seconds.
U2003
The BCM detects that the SPI serial data in circuit is greater than 4.5 v for greater than 5 seconds.
U2004
The BCM detects that the SPI serial data out circuit is less than 1.2 v for greater than 5 seconds.
U2005
The BCM detects that the SPI serial data out circuit is greater than 4.5 v for greater than 5 seconds.
U2006
The BCM detects that the SPI serial data clock circuit is less than 1.2 v for greater than 5 seconds.
U2007
The BCM detects that the SPI serial data clock circuit is greater than 4.5 v for greater than 5 seconds.
Your vehicle also uses class 2 data bus .
Class 2 Serial Data Link
The class 2 serial data link allows the following modules to communicate with each other:
• The body control module (BCM)
• The electronic brake control module (EBCM)
• The integrated radio chassis (IRC)
• The powertrain control module (PCM)
• The Remote Control Door Lock Receiver (RCDLR)
• The inflatable restraint sensing and diagnostic module (SDM)
The class 2 serial data link allows a scan tool to communicate with the above modules for diagnostic and testing purposes.
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