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Cat Man
Cat Man, Cat Engine Expert
Category: Medium and Heavy Trucks
Satisfied Customers: 8870
Experience:  I am ASE Master Truck Certified.
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I have a code Pid 231 Fmi 12. I can not find any info

Customer Question

Hello. I have a code Pid 231 Fmi 12. I can not find any info on it. Can you help
Submitted: 2 years ago.
Category: Medium and Heavy Trucks
Expert:  Cat Man replied 2 years ago.
Hi. Thanks for asking your question! I will try and help you out.
231-12 is defined as a J1939 device not responding. This means the engine ECM is not receiving a signal or message from a truck device. It could be a brake switch, clutch switch, vehicle speed signal, or cruise switches.
To determine which it is, I like to read the programming in the ECM and see what is programmed to J1939. Then look in status screen to see if each of these items is working and being read by the ECM.
Please reply back if you need more help or have more questions. I am happy to assist.

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