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What does an error code u2100 mean - 2005 Saturn ION

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Well a U code like U2100 is a communication error,meaning there is a bad computer in the car or a wires issue,one of the other computer in the car can not talk to the other so its send a loss of communication code as you got,,,,i would highly rec you go to the dealer for this concern

Posted on Oct 19, 2009

  • Anonymous Oct 19, 2009

    well a U code like U2100 is a communication error,meaning there is a bad computer in the car or a wires issue,one of the other computer in the car can not talk to the other so its send a loss of communication code as you got,,,,i would highly rec you go to the dealer for this concern



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The communication among control modules is performed primarily through the GMLAN high speed serial data circuit and the GMLAN low speed serial data circuits. The modules that need real time communication are attached to the high speed GMLAN network. The body control module (BCM) is the serial data gateway between the networks. The purpose of the gateway is to translate serial data messages between the GMLAN high speed buss and the GMLAN low speed buss. The controller area network (CAN) is another serial data communication network used on this vehicle which is dedicated to the electronic brake control module (EBCM) subsystem for stabilization. Below are more detailed descriptions of the individual networks. The gateway will interact with each network according to that network's transmission protocol. Refer to Body Control System Description and Operation for more information about the gateway.

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DTC U2100 00: Controller Area Network (CAN) Bus Communication
The GMLAN serial data circuits are controller area network (CAN) serial data buses used to communicate information between the control modules. Typical data transmission speeds must be high enough to ensure that a required real-time response is maintained. On this vehicle there are 2 totally different types of GMLAN serial data circuits, the high speed 2-wire circuit and low speed single wire circuit. Refer to Data Link Communications Description and Operation for the complete description of these buses. The GMLAN serial data circuits also communicate directly to the DLC connector. Messages are interpreted by the externally connected CANdi module which acts as a transceiver for the scan tool.
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