Chrysler ECU Computer Code 12

by Bob O’Neill and Bob Lincoln: Power Loss

Code 12 is set when the battery has been disconnected and the computer (ECU) has been reset.  The power limited light will not light and limp mode does not apply. This code shows up when power to the computer has been interrupted as when the computer has been reset buy disconnecting the battery.

Possible reasons for Code 12

Battery or power to the EUC disconnected – Code 12 is normal and doesn’t necessarily indicate a fault. If the battery has been disconnected or the electrical system has been worked on recently code 12 will indicate this. This code will is removed after about 15 engine starts.

Corroded Battery Terminals, Low Battery Voltage – Code 12 will be thrown if the system voltage drops too far below normal. This may be the result of a bad battery or the connection between the battery and the computer.  If the engine was jumped started and the battery terminals are bad and, this code may appear. 

Poor connection or bad wiring – Read the page ‘How to troubleshoot drivability issues’. Over time the pins in the connectors corrode/oxidize. Be sure to check the wiring and connections between the battery, power module, and logic module (or SMEC).  Fusible links from the battery should also be checked to be sure they are making good connection. 

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