B1939 Trouble Code

View B1939 obd/2 error code description and symptoms. B1939 engine photo

Low Speed Fuel Pump Primary Circuit Malfunction The PCM monitors the low speed fuel pump (LFP) primary circuit output from the PCM.
The test fails if: When the LFP circuit is commanded on (grounded), excessive current draw is detected on the LFP circuit; or when the LFP circuit is commanded off, voltage is not detected on the LFP circuit (the PCM expects to detect VPWR voltage coming through the low speed fuel pump relay coil to the LFP circuit). Open or shorted low fuel pump (LFP) circuit Open VPWR to low speed fuel pump relay Damaged low speed fuel pump relay Damaged PCM An open circuit or short to ground can only be detected with the low speed fuel pump.

A good starting point in your diagnosis is checking all system fuses and fusible links. This can be done using the DVOM on the voltage setting. You will want to test the fuses with circuits loaded. Some fuses will appear normal until a load is placed on their respective circuit; at which point they will fail. This has been the cause of many 'phantom malfunctions'. Consult your vehicle information source for fuse and fusible link locations. If all fuses are in working order, you may want to check TCM relay operation by swapping identical relays. Usually the horn relay, starter relay, fuel pump relay, air conditioning clutch relay, and controller relays are similar enough in design to swap for diagnostic purposes.

B1939 Error Code Repair Process :

When you turn on the ignition, the Service Engine Soon or Check Engine B1939 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If b1939 air bag passenger pressure switch circuit short to ground so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the b1939 air bag passenger pressure switch circuit short to ground.

Common Causes of B1939

A common cause of code B1939 is the failure of B1939 Air Bag Passenger Pressure Switch Circuit Short To Ground, but there are several other possible causes as well, such as ;

EVAP canister or fuel tank leaks
Camshaft advance mechanism binding (VCT unit)
Intake Valve Timing Control Solenoid Valve circuit poor electrical connection
Intake Valve Timing Control Solenoid Valve harness is open or shorted

B1939 Trouble Code

B1939 Error Code Repair Process :

Common Causes of B1939

B1939 code for all cars