Pinpoint Test S: No Module/Network Communication - No Power To The Diagnostic Tool

WARNING: This page is about a different car, the 2004 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Test Step

S1 CHECK THE DIAGNOSTIC TOOL TERMINALS FOR DAMAGE

Inspect the diagnostic tool terminals.
Are the terminals OK?

Result / Action to Take

Yes

GO to S2.

REPAIR the diagnostic tool terminals as necessary. TEST the system for normal operation.

Test Step

S2 CHECK THE C251 FOR DAMAGE

Key in OFF position.
Inspect the C251 pins for damage.
Are the pins OK?

Result / Action to Take

Yes

GO to S3.

REPAIR the C251. TEST the system for normal operation.

Test Step

S3 CHECK THE VOLTAGE TO THE C251

Measure the voltage between the C251 pin 16, circuit 40 (LB/WH), harness side and ground.

Fig 1: Checking Voltage To DLC C251
Courtesy of FORD MOTOR CO.
Is the voltage greater than 10 volts?

Result / Action to Take

Yes

GO to S4.

REPAIR the circuit. TEST the system for normal operation.

Test Step

S4 CHECK CIRCUITS 57 (BK) AND 570 (BK/WH) FOR AN OPEN

Measure the resistance between the C251 pin 4, circuit 57 (BK), harness side and ground; and between the C251 pin 5, circuit 570 (BK/WH), harness side and ground.

Fig 2: Checking Circuits 57 (BK) And 570 (BK/WH) For An Open
Courtesy of FORD MOTOR CO.
Are the resistances less than 5 ohms?

Result / Action to Take

Yes

CHECK the diagnostic tool. TEST the system for normal operation.

REPAIR the circuit in question. TEST the system for normal operation.