Pinpoint Test N: No Power To The Scan Tool

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Normal Operation 

The scan tool is connected to the data link connector (DLC) to communicate with the high speed controller area network (HS-CAN), the standard corporate protocol (SCP), and the International Standards Organization (ISO) 9141 network. Voltage for the scan tool is provided by circuit 40 (LB/WH). Ground is provided by circuits 57 (BK) and 570 (BK/WH).

This pinpoint test is intended to diagnose the following:

• Fuse
• Wiring, terminals or connectors
• Scan tool

PINPOINT TEST N: NO POWER TO THE SCAN TOOL 

1. N1 CHECK DLC PINS FOR DAMAGE 
   NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.
   • Disconnect the scan tool cable from the DLC.
   Fig 1: Checking DLC Pins For Damage
   Courtesy of FORD MOTOR CO.
   • Inspect the DLC pins 4, 5 and 16 for damage.
   • Are the DLC pins 4, 5 and 16 OK? 
   1. YES  : Go to  N2.
   2. NO  : REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. N2 CHECK THE DLC VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
   • Measure the voltage between the DLC C251-16, circuit 40 (LB/WH), harness side and ground.
   • Is the voltage greater than 10 volts? 
   1. YES  : Go to  N3.
   2. NO  : VERIFY the central junction box (CJB) fuse 16 (20A) is OK. If OK, REPAIR the circuit. REPEAT the network test with the scan tool.
3. N3 CHECK THE DLC GROUND CIRCUITS FOR AN OPEN 
   • Measure the resistance between the DLC C251-4, circuit 57 (BK), harness side and ground; and between the DLC C251-5, circuit 570 (BK/WH), harness side and ground.
   • Are the resistances less than 5 ohms? 
   1. YES  : REPAIR the scan tool. REPEAT the network test with the scan tool.
   2. NO  : REPAIR the circuit in question. REPEAT the network test with the scan tool.