Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2005 Mercury Mariner 3.0 1, FWDFACTORY OEM SERVICE PROCEDURE

Data Link Connector (DLC) Connector End View (C251)

Fig 1: Data Link Connector (DLC) Connector End View (C251)

Courtesy of FORD MOTOR CO.

C251 CONNECTOR SPECIFICATION

Pin	Circuit	Gauge	Circuit Function
1	*	*	not used
2	*	*	not used
3	1847 (WH-OG)	20	Medium speed CAN bus +
4	57 (BK)	20	Ground
5	570 (BK-WH)	20	Ground
6	1908 (WH)	20	High speed CAN bus +
7	70 (LB-WH)	20	ISO Bus
8	*	*	not used
9	*	*	not used
10	*	*	not used
11	1848 (PK-OG)	20	Medium speed CAN bus -
12	*	*	not used
13	107 (VT)	20	Flash/EEPROM power supply
14	1909 (BK)	20	High speed CAN bus -
15	*	*	not used
16	956 (OG-LG)	20	Voltage supplied at all times (overload protected)

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.

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