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Ford Mustang DTC B1265:24 and B1266:24 - Understanding 'Signal Stuck High/Low' Voltage Ranges

Model: Ford Mustang Fault Code: B1265 Posted: 2018-01-21 04:54

Hi everyone, I'm trying to understand what the voltage range means when the ECU reports a 'signal stuck high' or 'signal stuck low' for DTC codes B1265:24 and B1266:24 on my Ford Mustang. Specifically, what does 'low' mean in this context? Is it a short to ground, or is it a specific voltage level like 0.7V, 1V, or 5V? I'm particularly confused about how the ECU interprets these signals — for example, if there's a reference circuit of 5V, does the ECU consider a range from 0.5V to 4.5V as normal? Then values below 0.5V would be 'stuck low', and above 4.5V would be 'stuck high'. Does this apply to turn signal, stop lamp, or tail light circuits? Any insight into the actual voltage thresholds for these error codes on Ford Mustang models? Thanks in advance!

Related fault codes
B1265B1266
Comments (5)
Anonymous 2018-01-21 13:08

The most accurate source is always the factory service manual. Voltage ranges for 'stuck high' or 'stuck low' depend on both sensor type and ECU interpretation. For example, in a 5V reference circuit, the ECU typically defines a valid window between 0.5V and 4.5V. Any signal below 0.5V is considered 'stuck low', while any above 4.5V is 'stuck high'. This applies to various lighting circuits — always verify with the specific vehicle's wiring diagram. Are you experiencing this error on a particular Ford Mustang model or year?

Anonymous 2018-01-21 13:19

I believe 'high' and 'low' are not equivalent to open or short circuits. For DTC B1265:24 and B1266:24, the error is specifically 'Left/Right Turn Lamp Feedback: Signal Stuck High'. This indicates that the ECU detected a high signal from the turn lamp circuit when it should have been low (or vice versa).

Anonymous 2018-01-21 15:47

If the Body Control Module (BCM) fails to detect current flow in the turn signal or lamp circuit, it will set a 'signal stuck high' error. This can be caused by an open circuit, short to power, or faulty wiring/connector. Recommended troubleshooting steps: check for continuity and proper voltage in the lamp circuit, inspect connectors, and test for correct ground and signal integrity.

Anonymous 2018-01-21 15:59

I'm trying to understand how Lamp Outage Detection works on this model. In my setup, I have 12V at the lamps (turn signals, stop lights, tail lights), GND is solid, and the 'L-Outage' detection line shows 5V. But surprisingly, the L-Outage signal comes from the BCM-B side, not from the lamp itself — which contradicts my initial assumption that the BCM sends 12V to all lamps and expects a 5V return from the lamp when active. This suggests the detection logic is internal to the BCM. I'd like to know exactly which pin in the connector serves as the 'detection line' and how this system functions.

Anonymous 2018-01-21 16:25

Refer to service manual section 417-01: Exterior Lighting Troubleshooting for detailed diagnostic procedures. Also, search Google using specific error codes like 'Ford Mustang B1265 B1266 DTC signal stuck high' to find official technical references and test protocols.