Code Definition

P1107 — Dual Alternator lower circuit

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Ford

About P1107

P1107 is a manufacturer-specific powertrain diagnostic trouble code recorded for Ford vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1107 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1107 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The P1107 code indicates a fault in the lower or secondary alternator monitor and control circuit of a Ford dual alternator system. Dual alternator systems use a second alternator for additional electrical capacity, typically on diesel and heavy duty applications, and the PCM watches a monitor or communication circuit to confirm the lower unit is connected and responding. This code is set when the PCM sees an electrical problem on that circuit, such as an open, a short, or an implausible signal, rather than a charging output shortfall on its own. The result can be a charging system warning and...

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