Ford Repair Questions? Ask a Mechanic for Answers ASAP
Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner past midnight.
Code 1633 means the keep alive memory power circuit to the PCM has low voltage. Use the link below.
If the pin 55 has good power then you would replace the PCM for this issue. However this code will rarely ever cause a running issue. Stalling at red lights can be related to the vehicle behind on maintenance, sensors and components needing to be cleaned, and or a failing idle air control valve.
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Hello again Chris here,