B1240 - Start Button Mode Indicator Circuit Short

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What does this mean?

B1240 Possible Causes

  • Faulty Start/Stop Switch Indicator
  • Start/Stop Switch Indicator harness is open or shorted
  • Start/Stop Switch Indicator circuit poor electrical connection
  • Faulty Body Control Module (BCM)

How do I fix code B1240

    Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

B1240 Tech Notes

B1240:11 Start Button Mode Indicator Circuit Short to Ground
B1240:15 Start Button Mode Indicator Circuit Short to Battery or Open

Cost of diagnosing the B1240 code

    Labor: 1.0

    The cost of diagnosing the B1240 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

B1240 Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

B1240 Meaning

The Body Control Module (BCM) uses a Field Effect Transistor (FET) as circuit protection for the start/stop switch indicator and as an electronic switch to turn the start/stop switch indicator on and off. The FET receives fused battery voltage from BCM. When the start/stop switch is pressed a voltage and ground signal are sent to the BCM. When the vehicle enters RUN or START mode, the BCM forward biases the FET which provides voltage to the amber LED in the start/stop switch, illuminating the word ENGINE.
OBDII Code B1240 - Start Button Mode Indicator Circuit Short - Engine-Codes.com

B1240 More Information

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B1240 Information for specific makes

  • B1240 ACURA Problem In The Mode Control Linkage, Doors, Or Motor Circuit
  • B1240 FORD Start Button Mode Indicator Circuit Short
  • B1240 HONDA Problem In The Mode Control Linkage, Doors, Or Motor Circuit
  • B1240 LINCOLN Start Button Mode Indicator Circuit Short
  • B1240 MERCURY Start Button Mode Indicator Circuit Short

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