Restraint Control Module (RCM) C2041a
Smart Junction Box (SJB) C2280c
Pinpoint Test A: No Communication With The Instrument Cluster
Normal Operation
The instrument cluster communicates interactively with other electronic modules using the communication network. With the ignition switch in the START/RUN position, the instrument
cluster receives voltage from the smart junction box (SJB) fuse 16 (5A), circuit 489 (PK/BK), and SJB fuse 19 (5A) circuit 1266 (RD/YE). With the ignition switch in the OFF position, the
instrument cluster receives its keep-alive voltage from the SJB fuse 8 (10A), circuit 1001 (WH/YE). The instrument cluster is grounded through circuit 1205 (BK).
Possible Causes
circuit 489 (PK/BK) open
circuit 1001 (WH/YE) open
circuit 1205 (BK) open
circuit 1266 (RD/YE) open
instrument cluster
PINPOINT TEST A: NO COMMUNICATION WITH THE INSTRUMENT CLUSTER
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
4 (C433) 1356 (LG/VT) fuel level variable
input signal
0 volts, less than 5 ohms between the fuel pump sender and the SJB.
Pin Number
(s) Circuit Designation/Description Normal Condition/Measurement
19 608 (BK/YE) air bag warning indicator control
circuit
Less than 5 ohms between the restraint control module (RCM) and the instrument cluster. Greater than 10,000 ohms
between the RCM and ground.
22 1083 (LB/PK) safety belt warning indicator
control circuit
Less than 5 ohms between the RCM and the instrument cluster. Greater than 10,000 ohms between the RCM and
ground.
Pin Number
(s) Circuit Designation/Description Normal Condition/Measurement
31 1357 (LB/YE) fuel level signal return 0 volts, less than 5 ohms between the SJB and the fuel sender. Greater than 10,000 ohms between the SJB and ground.
35 512 (TN/LG) brake fluid level return circuit 0 volts, less than 5 ohms between the SJB and the brake fluid level switch. Greater than 10,000 ohms between the SJB
and ground.
42 208 (GY) oil pressure signal circuit Less than 5 ohms between the SJB and the oil pressure switch. Greater than 10,000 ohms between the SJB and ground.
43 29 (YE/WH) fuel level variable input signal 0 volts, less than 5 ohms between the SJB and the remote fuel sender. Greater than 10,000 ohms between the SJB and
ground.
44 1356 (LG/VT) fuel level variable input signal 0 volts, less than 5 ohms between the SJB and the fuel pump sender. Greater than 10,000 ohms between the SJB and
ground.
48 547 (LG/YE) brake fluid level signal circuit 0 volts, less than 5 ohms between the SJB and the brake fluid level switch. Greater than 10,000 ohms between the SJB
and ground.
50 1309 (RD/YE) parking brake switch input
circuit
0 volts, less than 5 ohms between the SJB and the parking brake switch. Greater than 10,000 ohms between the SJB and
ground.
Test Step Result / Action to Take
A1 CHECK THE INSTRUMENT CLUSTER VOLTAGE SUPPLY
Ignition OFF.
Disconnect: Instrument Cluster C220.
Ignition ON.
Measure the voltage between the instrument cluster, harness side and ground as follows:
Yes
GO to A2.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the
2005 Mustang Workshop Manual
http://www.fordtechservice.dealerconnection.com/pubs/content/
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