Pinpoint Test A: No Communication With The Smart Junction Box (SJB)

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

A1 CHECK THE SJB VOLTAGE SUPPLY CIRCUITS FOR AN OPEN

Key in OFF position.
Disconnect: SJB C2280a.
Disconnect: SJB C2280g.

Using SJB VOLTAGE SUPPLY CIRCUITS SPECIFICATION TABLE , measure the voltage between the SJB, harness side and ground:

SJB VOLTAGE SUPPLY CIRCUITS SPECIFICATION TABLE

SJB Connector-pin	Circuit
C2280a-29	1231 (RD/WH)
C2280g-1	906 (RD/OG)
C2280g-2	905 (GY/LB)

Fig 1: Checking SJB Voltage Supply Circuits For Open

Courtesy of FORD MOTOR CO.

Are the voltages greater than 10 volts?

Yes: GO to A2.

No: VERIFY the battery junction box (BJB) fuses 1 (80A), 18 (40A) and 28 (80A) are OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.

A2 CHECK THE SJB GROUND CIRCUIT FOR AN OPEN
- Connect: SJB C2280g.
- Disconnect: SJB C2280e.
- Measure the resistance between the SJB C2280a-30, circuit 1203 (BK/LB), harness side and ground; and between the SJB C2280e-3, circuit 1205 (BK), harness side and ground.
  
  Fig 2: Checking SJB Ground Circuit For Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
Yes: REFER to COMMUNICATIONS NETWORK to continue communication diagnosis.

No: REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.