Q: Could hardwiring the cooling fan cause the ECM to burn out? After trying emissions the security lock wouldn't allow starting.

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I hardwired the cooling fan on and tried to go through emissions. Their computer said they couldn't read it. Then It wouldn't start, The security lockout has not allowed the vehicle to start since. A new mechanic said I need new PCM. I feel like I should get a new fan & new computer & try that. I can't afford going to Ford. Would bypassing the relay fry the computer?

My car has 140000 miles.
My car has an automatic transmission.

The circuit powering the cooling fans does not run "through" the PCM and consequently bypassing the fan relay will have no effect on the PCM, or anything, for that matter although you might wear out the fan motor early from continuous operation. In this particular circumstance, involving the fan, the only possible mechanism through which any "re-wiring" could damage other components in the electrical system is if you created a short circuit. If the fan works when you power it directly, you do not need a new fan. If the fan is not turning on, or cycling as required by the cooling system, the control circuit for the fan should be diagnosed and repaired. The only time you would ever need a new computer (which, in practice, on almost all modern cars is "never") is if you have in hand a written diagnostic, with specific electrical test data, that is evidence, documenting an actual fault with the computer. If you do not have an actual diagnostic that condemns the computer, you should not replace it. If the vehicle is presently not starting, to temporarily override the security lockout, please see these instructions. If those instructions do not resolve the no start, please request a no start diagnostic and the responding mechanic will get your car started. That same mechanic can diagnose and resolve the issue with the control circuit to the cooling fan. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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