Ford F150 Pickup. Instruction - part 1727

detects resistance that is out of the expected range (high or low), it will store Diagnostic Trouble Code (DTC) 
B1877 or B1885 in memory and flash Code 46 on AIR BAG warning light. 

Possible Causes 

A left seat belt pretensioner out of range resistance fault can be caused by out of range resistance in Light 
Green/Red wire, out of range resistance in Light Green/Black wire, out of range resistance in left seat belt 
pretensioner or faulty RCM. 

1. Check for hard or intermittent DTC 

 
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). See USING 
SCAN TOOL under DIAGNOSTICS. Turn ignition switch to RUN position. Retrieve and record any 
continuous DTCs. See RETRIEVING FAULT CODES under DIAGNOSTICS. Perform on-demand 
self-test. See ON-DEMAND SELF-TEST under DIAGNOSTICS. If DTC B1877 or B1885 was 
retrieved during on-demand self-test, fault is hard. Go to next step. If DTC B1877 or B1885 was not 
retrieved, fault is intermittent. Go to step 4 . 

2. Check left pretensioner circuit 

 
Using scan tool, select PID/Data Monitor and Record. Select PID D-PRTNR. If resistance is less than 1.7 
ohms or greater than 3.2 ohms, go to next step. If resistance is 1.7-3.2 ohms, replace RCM. See 
RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Go to step 5 . 

3. Check left pretensioner 

 
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under 
DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. With PID 
D-PRTNR selected on scan tool, read pretensioner resistance. If resistance is less than 1.7 ohms or greater 
than 3.2 ohms, repair Light Green/Red wire (circuit No. 1079) and/or Light Green/Black wire (circuit No. 
1080). See WIRING DIAGRAMS . Go to step 5 . If resistance is 1.7-3.2 ohms, replace left seat belt 
pretensioner. See SEAT BELT PRETENSIONERS under REMOVAL & INSTALLATION. 

4. Check for intermittent fault 

 
Refer to continuous DTCs recorded in step 1 . If DTC retrieved in step 1 was an intermittent fault, check 
for cause of intermittent faults in Light Green/Red wire (circuit No. 1079) and Light Green/Black wire 
(circuit No. 1080). See WIRING DIAGRAMS . Attempt to recreate fault by flexing wire harness and 
cycling ignition switch frequently. Repair any intermittent problems found. Go to next step. If DTC 
retrieved in step 1 was not an intermittent fault. Go to next step. 

5. Check for additional DTCs 

 
Refer to continuous DTCs recorded in step 1 . If any continuous DTCs were retrieved, go to diagnostic 
trouble code identification table for direction to appropriate test. See DIAGNOSTIC TROUBLE CODE 
(DTC) IDENTIFICATION table. DO NOT clear any DTCs until all DTCs have been resolved. If no 
continuous DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING 

 

2003 Ford Pickup F150 

2003 ACCESSORIES/SAFETY EQUIPMENT Air Bag Restraint Systems - F150 Pickup

  

SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear all DTCs. See CLEARING 
FAULT CODES under DIAGNOSTICS.  

TEST F: LEFT PRETENSIONER CIRCUIT SHORT TO BATTERY OR IGNITION (DTC B1878) 

Description 

Restraints Control Module (RCM) monitors circuits to left seat belt pretensioner. When RCM detects a circuit 
short to battery, it will store Diagnostic Trouble Code (DTC) B1878 in memory and flash Code 17 on AIR 
BAG warning light. 

Possible Causes 

A left seat belt pretensioner circuit short to battery fault can be caused by short to battery in Light Green/Red 
wire, short to battery in Light Green/Black wire, short to battery in left seat belt pretensioner or faulty RCM. 

1. Check for hard or intermittent DTC 

 
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). See USING 
SCAN TOOL under DIAGNOSTICS. Turn ignition switch to RUN position. Retrieve and record any 
continuous DTCs. See RETRIEVING FAULT CODES under DIAGNOSTICS. Perform on-demand 
self-test. See ON-DEMAND SELF-TEST under DIAGNOSTICS. If DTC B1878 was retrieved during 
on-demand self-test, fault is hard. Go to next step. If DTC B1878 was not retrieved, fault is intermittent. 
Go to step 4 . 

2. Check left pretensioner 

 
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under 
DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. Perform on-
demand self-test. If DTC B1878 was retrieved during on-demand self-test, go to next step. If DTC B1878 
was not retrieved, replace left seat belt pretensioner. See SEAT BELT PRETENSIONERS under 
REMOVAL & INSTALLATION. Go to step 5 . 

3. Check left pretensioner circuits 

 
Turn ignition switch to OFF position. Access RCM and disconnect harness connector. See 
RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Remove left 
pretensioner simulator from harness connector. Measure voltage between ground and harness side of 
RCM connector terminals No. 18 (Light Green/Red wire, circuit No. 1079) and 22 (Light Green/Black 
wire, circuit No. 1080) separately. See Fig. 14 . If voltage is more than 0.2 volt in either circuit, repair 

NOTE:

Before proceeding, see AIR BAG SAFETY PRECAUTIONS . 
Diagnostic tests or repairs are not to be performed on seat belt pretensioner 
system with front seats installed in vehicle. Prior to diagnosis or repair of 
pretensioner system, remove front seats and ensure appropriate pretensioner 
simulators are installed at pretensioner connectors. See FRONT SEAT under 
REMOVAL & INSTALLATION.

 

2003 Ford Pickup F150 

2003 ACCESSORIES/SAFETY EQUIPMENT Air Bag Restraint Systems - F150 Pickup

  

short to battery in appropriate circuit. See WIRING DIAGRAMS . Go to step 5 . If voltage is less than 
0.2 volt in both circuits, replace RCM. Go to step 5 . 

4. Check for intermittent fault 

 
Refer to continuous DTCs recorded in step 1 . If DTC retrieved in step 1 was an intermittent fault, check 
for cause of intermittent faults in Light Green/Red wire (circuit No. 1079) and/or Light Green/Black wire 
(circuit No. 1080). See WIRING DIAGRAMS . Attempt to recreate fault by flexing wire harness and 
cycling ignition switch frequently. Repair any intermittent problems found. Go to next step. If DTC 
retrieved in step 1 was not an intermittent fault. Go to next step. 

5. Check for additional DTCs 

 
Refer to continuous DTCs recorded in step 1 . If any continuous DTCs were retrieved, go to diagnostic 
trouble code identification table for direction to appropriate test. See DIAGNOSTIC TROUBLE CODE 
(DTC) IDENTIFICATION table. DO NOT clear any DTCs until all DTCs have been resolved. If no 
continuous DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING 
SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear all DTCs. See CLEARING 
FAULT CODES under DIAGNOSTICS.  

TEST G: LEFT PRETENSIONER CIRCUIT SHORT TO GROUND (DTC B1879) 

Description 

Restraints Control Module (RCM) monitors circuits to left seat belt pretensioner. When RCM detects a circuit 
short to ground, it will store Diagnostic Trouble Code (DTC) B1879 in memory and flash Code 17 on AIR 
BAG warning light. 

Possible Causes 

A left seat belt pretensioner circuit short to ground fault can be caused by short to ground in Light Green/Red 
wire, short to ground Light Green/Black wire, short to ground in left seat belt pretensioner or faulty RCM. 

1. Check for hard or intermittent DTC 

 
Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). See USING 
SCAN TOOL under DIAGNOSTICS. Turn ignition switch to RUN position. Retrieve and record any 
continuous DTCs. See RETRIEVING FAULT CODES under DIAGNOSTICS. Perform on-demand 
self-test. See ON-DEMAND SELF-TEST under DIAGNOSTICS. If DTC B1879 was retrieved during 
on-demand self-test, fault is hard. Go to next step. If DTC B1879 was not retrieved, fault is intermittent. 

NOTE:

Before proceeding, see AIR BAG SAFETY PRECAUTIONS . 
Diagnostic tests or repairs are not to be performed on seat belt pretensioner 
system with front seats installed in vehicle. Prior to diagnosis or repair of 
pretensioner system, remove front seats and ensure appropriate pretensioner 
simulators are installed at pretensioner connectors. See FRONT SEAT under 
REMOVAL & INSTALLATION.

 

2003 Ford Pickup F150 

2003 ACCESSORIES/SAFETY EQUIPMENT Air Bag Restraint Systems - F150 Pickup

  

Go to step 4 . 

2. Check left pretensioner 

 
Turn ignition switch to OFF position. Disable air bag system. See DISABLING SYSTEM under 
DISABLING & ACTIVATING AIR BAG SYSTEM. Turn ignition switch to RUN position. Perform on-
demand self-test. If DTC B1879 was retrieved during on-demand self-test, go to next step. If DTC B1879 
was not retrieved, replace left seat belt pretensioner. See SEAT BELT PRETENSIONERS under 
REMOVAL & INSTALLATION. Go to step 5 . 

3. Check left pretensioner circuits 

 
Turn ignition switch to OFF position. Access RCM and disconnect harness connector. See 
RESTRAINTS CONTROL MODULE (RCM) under REMOVAL & INSTALLATION. Remove left 
pretensioner simulator from harness connector. Measure resistance between ground and harness side of 
RCM connector terminals No. 18 (Light Green/Red wire, circuit No. 1079) and 22 (Light Green/Black 
wire, circuit No. 1080) separately. See Fig. 14 . If resistance is less than 10 k/ohms in either circuit, repair 
short to ground in appropriate circuit. See WIRING DIAGRAMS . Go to step 5 . If resistance is more 
than 10 k/ohms in both circuits, replace RCM. Go to step 5 . 

4. Check for intermittent fault 

 
Refer to continuous DTCs recorded in step 1 . If DTC retrieved in step 1 was an intermittent fault, check 
for cause of intermittent faults in Light Green/Red wire (circuit No. 1079) and/or Light Green/Black wire 
(circuit No. 1080). See WIRING DIAGRAMS . Attempt to recreate fault by flexing wire harness and 
cycling ignition switch frequently. Repair any intermittent problems found. Go to next step. If DTC 
retrieved in step 1 was not an intermittent fault. Go to next step. 

5. Check for additional DTCs 

 
Refer to continuous DTCs recorded in step 1 . If any continuous DTCs were retrieved, go to diagnostic 
trouble code identification table for direction to appropriate test. See DIAGNOSTIC TROUBLE CODE 
(DTC) IDENTIFICATION table. DO NOT clear any DTCs until all DTCs have been resolved. If no 
continuous DTCs were retrieved, reconnect air bag system. Activate air bag system. See ACTIVATING 
SYSTEM under DISABLING & ACTIVATING AIR BAG SYSTEM. Clear all DTCs. See CLEARING 
FAULT CODES under DIAGNOSTICS.  

TEST H: RIGHT PRETENSIONER CIRCUIT RESISTANCE HIGH OR LOW (DTC B1881 OR 1886) 

Description 

NOTE:

Before proceeding, see AIR BAG SAFETY PRECAUTIONS . 
Diagnostic tests or repairs are not to be performed on seat belt pretensioner 
system with front seats installed in vehicle. Prior to diagnosis or repair of 
pretensioner system, remove front seats and ensure appropriate pretensioner 
simulators are installed at pretensioner connectors. See FRONT SEAT under 
REMOVAL & INSTALLATION.

 

2003 Ford Pickup F150 

2003 ACCESSORIES/SAFETY EQUIPMENT Air Bag Restraint Systems - F150 Pickup