I disconnected the battery and now after reconnected it w...


I disconnected the battery and now after reconnected it won't crank, and security light is flashing Mechanic's Assistant: Does the light flash, blink or stay solid? Have you tried to reset the security system? It flashes ...

I disconnected the battery and now after reconnected it won't crank, and security light is flashing Mechanic's Assistant: Does the light flash, blink or stay solid? Have you tried to reset the security system? It flashes then stops. I'm not sure how to reset the security system Mechanic's Assistant: What is the make/model/year of your car? 2007 ford expedition Mechanic's Assistant: Are you fixing your Expedition yourself? What have you tried so far? I'm fixing myself. And I tried disconnecting the battery and waiting 10 min then reconnected and it did the same thing Mechanic's Assistant: Anything else you want the Mechanic to know before I connect you? Yes, all I did when disconnecting the battery was run a power cable from the battery to an amplifier

Automotive Expert
Good Afternoon, my name is \*\*\*\*\* \*\*\*\*\* ill be helping you, so sorry to hear about the issues here on the Expedition. I know how frustrating it can be to deal with security system issues. The security light flashing indicates that the vehicle no longer recognizes the key used to start the vehicle. This is a common issue if a battery is low or disconnected. There is not many things you can do to fix this yourself. You can insert the key into the ignition and turn it on and leave it there for 10 minutes and then turn it off for 30 seconds and then repeat that process two more times. You can also attempt to lock and unlock the drivers door a few times. If neither of these tricks work you will need to visit the dealer or a locksmith to have the system reset manually.

Ok now the security light is off but it's not cranking still
Automotive Expert
we still need to suspect a security system issue since they rarely if ever fix themselves. if not we can also bypass the [starter](/topics-starter-ford/) relay with a jumper wire at pins 30 and 87 to ensure that the starter and wiring circuit check out

I still don't understand why it would cause this issue when I've disconnected the battery cable many times and it didn't affect it
Automotive Expert
it can be intermittent. there are a lot of factors that go into it but the number cause of security issue is a dead or disconnected battery.

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