Pinpoint Test A: The Smart Junction Box (SJB) Does Not Respond To The Diagnostic Tool

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

A1 CHECK THE SJB CONNECTORS FOR DAMAGE
- Key in OFF position.
- Disconnect: SJB C2280a, C2280c and C2280d.
- Inspect the SJB connectors for damage.
- Are the SJB connectors OK?
- Yes : GO to A2.
- No : REPAIR the SJB connector in question. CARRY OUT the data link diagnostics test.

A2 CHECK THE SJB POWER CIRCUITS

Key in ON position.

Measure the voltage between the SJB power circuits and ground. Refer to the following table for connector, pin and circuit numbers.

Fig 1: Checking SJB Power Circuits

Courtesy of FORD MOTOR CO.

Connector	Pin	Circuit
C2280a	1	1523 (DG)
C2280a	29	1524 (DB)
C2280a	32	1118 (RD)

Are the voltages greater than 10 volts?

Yes : GO to A3.
No : REPAIR the circuit in question.
CARRY OUT the data link diagnostics test.

A3 CHECK THE SJB GROUND CIRCUITS
- Key in OFF position.
- Measure the resistance between the SJB C2280c pin 1, circuit 570 (BK/WH), harness side and ground; and between the SJB C2280c pin 8, circuit 57 (BK), harness side and ground.
  
  Fig 2: Checking SJB Ground Circuits
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
1. Yes : GO to A4.
2. No : REPAIR the circuit in question.
  CARRY OUT the data link diagnostics test.
A4 CHECK ISO COMMUNICATION CIRCUIT 70 (LB/WH) BETWEEN THE DLC C251 AND THE SJB C4 FOR AN OPEN
- Measure the resistance between the DLC C251 pin 7, circuit 70 (LB/WH), harness side and the SJB C2280d pin 7, circuit 70 (LB/WH), harness side.
  
  Fig 3: Checking ISO Communication Circuit 70 (LB/WH) Between DLC C251 And SJB C4 For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
1. Yes : REFER to MODULE COMMUNICATIONS NETWORK to continue communication diagnostics.
2. No : REPAIR the circuit. CARRY OUT the data link diagnostics test.