Transfer Case Shift Motor Short Circuit To Battery
Table of contents
P1840 MERCURY Possible Causes
- Faulty Transfer Case Control Module (TCCM)
- Transfer Case Control Module harness is open or shorted
- Transfer Case Control Module circuit poor electrical connection
- Faulty Transfer case
- Faulty Front axle assembly
How do I fix code P1840 MERCURY?
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.
Cost of diagnosing the P1840 MERCURY code
The cost of diagnosing the P1840 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P1840 MERCURY Description
The Mode Select Switch (MSS) communicates the operator’s choice to the Transfer Case Control Module (TCCM). As the TCCM commands the gearmotor encoder assembly to 4H mode, the transfer case shift fork moves to engage 4H mode which also engages the dual-cone synchronizers to bring the front driveline to the same speed as the rear driveline. The TCCM also activates the hublock vacuum solenoid, providing a vacuum and engaging the Constant Vacuum Hublock (CVH) at each front wheel. If the vehicle is not responding to the operator’s intentions, systematically check the necessary inputs and outputs of the TCCM, components of the transfer case, CVH components, and axle shafts. Check all circuits for opens and shorts to power or ground.