Engine Controls - MIL ON/DTC P0191
TSB 05-26-212/31/05
MIL ON DTC P0191 WITH OR WITHOUT VARIOUS
DRIVABILITY SYMPTOMS AND/OR ADDITIONAL
DTCS
FORD:
2004-2005 Explorer
MERCURY:
2004-2005 Mountaineer
ISSUE
Some 2004-2005 Explorer 4dr/Mountaineer vehicles may exhibit a malfunction indicator lamp (MIL) on concern with diagnostic trouble code (DTC) P0191 being stored, which may be accompanied by other various DTCs or drivability symptoms.
ACTION
Refer to the Service Procedure for a description of DTC P0191 strategy, possible causes and additional diagnostic information to supplement the Powertrain Controls/Emissions Diagnosis (PC/ED) manual.
SERVICE PROCEDURE
General Information:
The comprehensive component monitor (CCM) checks the fuel rail pressure (FRP) for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time. A "FRP" PID value during key on engine running (KOER) of 138 kPa (20 psi) to 413 kPa (60 psi) is acceptable.
NOTE
A FRP READING HIGHER OR LOWER THAN EXPECTED CAN RESULT IN A P0191 BEING STORED.
Possible Causes:
^ High fuel pressure
^ Low fuel pressure
^ Wiring/Circuit faults
^ Vacuum leaks
^ Low or no fuel
^ Damaged FRP sensor
Repair Procedure:
NOTE
USE THE 2005 PC/ED, WIRING DIAGRAMS, AND WORKSHOP MANUALS FOR BOTH 2004 AND 2005 MY VEHICLES FOR THIS CONCERN.
1. Using WDS or equivalent to retrieve DTC and record.
2. Is DTC P0191 retrieved?
a. If DTC P0191 is retrieved, go to Step 3.
b. If DTC P0191 is not retrieved, this TSB does not apply, refer to the PC/ED manual and perform normal diagnostics.
3. Are DTCs P1233, P1235, or P1237 present?
a. If DTC P1233, P1235, or P1237 is retrieved, go to Step 4.
b. If DTC P1233, P1235 or P1237 is not retrieved, go to Step 10.
4. Is DTC P1233 present?
a. If DTC P1233 is present, go to Step 5.
b. If DTC P1233 is not present, go to Step 6.
5. Check possible sources below and repair as necessary.
^ Check if Ground G401 is (RH D-Pillar Lower) clean and secured (Figure 1)
^ Check Connector C4033 at FPDM for loose connector, terminal push o5t, or a spread connector terminal (Figure 1)
^ Check Connection to the inertia switch connector C282 (Figure 2)
^ Check fuel pump relay located in BJB C1051 (Figure 3)
^ Check for terminal push out or terminal spread Connector C175B at PCM Pin 21 (FP MONITOR) (Figure 4)
^ Check for wire chafing between FPDM and PCM
^ Check for wire chafing or pinching between FPDM and Fuel Pump. Areas of attention are the "top" of the frame rearward and forward of RR Body Mount as well as behind the rear bumper cover (Figure 5). If circuit "FP POWER" is shorted to ground, the 20A fuse F1.26 located in BJB will open
a. If no issues with the wiring have been identified, refer to appropriate section in the 2005 online PC/ED for normal diagnostics.
b. If DTC P1235 is present, go to Step 7.
c. If DTC P1237 is present, go to Step 9.
6. Is DTC P1235 present?
a. If DTC P1235 is present, go to Step 7.
b. If DTC P1235 is not present, go to Step 8.
7. Check possible sources below and repair as necessary:
^ Check Connector C4033 at FPDM for loose connector, terminal push out or a spread connector terminal. (Figure 1)
^ Check for terminal push out or a spread terminal connector at C175B, PCM Pin 12 (FP CONTROL) (Figure 4)
^ Check for wire chafing between FPDM and PCM
a. If no issues with the wiring have been identified, refer to appropriate section in the 2005 online PC/ED for normal diagnostics.
b. If DTC P1237 is present, go to Step 9.
8. Is DTC P1237 present?
a. If DTC P1237 is present, go to Step 9.
b. If DTC P1237 is not present, go to Step 3.
9. Check possible sources below and repair as necessary:
^ Check for wire chafing or pinching between FPDM and fuel pump. Areas of attention are top of the frame rearward and forward of RR Body Mount as well as behind the rear bumper cover (Figure 5)
NOTE
IF "FP RETURN" IS SHORTED TO GROUND, THE FUEL RAIL PRESSURE WILL DEFAULT TO AROUND 483-517 kPa (70-75 PSI).
a. If no issues with the wiring have been identified, refer to appropriate section in the 2005 online PC/ED for normal diagnostics.
10. Is P0191 the only DTC present?
a. If DTC P0191 is the only DTC present, go to Step 11.
b. If DTCs other than P0191 are retrieved, service those DTCs first following the appropriate service procedures in the 2005 online PC/ED and retest.
11. Check possible sources below and repair as necessary:
^ Check Fuse F1.26, located in Battery Junction Box (BJB)
^ Check Connector C4033 at FPDM for loose connector, terminal push out, or a spread connector terminal (Figure 1)
^ Check Connector C410 at AJB for loose connector, terminal push out, or a spread connector terminal (Figure 6)
^ Check Connector C422 in-line 14407-13A409 for loose connector, terminal push out, or a spread connector terminal (Figure 7)
^ Check Connector C4074 at fuel pump for loose connector, terminal push out or a spread connector terminal (Figure 8)
^ Check for a broken wire, chafing or pinching between FPDM and Fuel Pump. Areas of attention are top of the frame rearward and forward of RR Body Mount as well as behind the rear bumper cover (Figure 5)
a. If checks are ok, refer to the 2005 online PC/ED Manual PPT "HC" to check the Fuel Delivery System and repair as necessary.
NOTE
MECHANICAL FUEL PRESSURE CHECKS MAY REQUIRE THE USE OF ROTUNDA TOOL PART # 310-D002 (D8SL-9974-B) AND/OR 310-D003 (D8SL-9974-C); REFER TO THE WORKSHOP MANUAL FOR ADDITIONAL INFORMATION.
NOTE
WHEN COMPARING FUEL PRESSURE READINGS BETWEEN THE FUEL RAIL PRESSURE SENSOR ("FRP" PID) AND A MECHANICAL GAUGE, THE READINGS WILL NOT BE EQUAL. TO CALCULATE THE APPROXIMATE VALUE, SEE THE FOLLOWING FORMULA: (FRP - MAP = MECHANICAL FUEL PRESSURE GAUGE READING) SEE REFERENCE BELOW:
NOTE
ALL READINGS ARE AT SEA LEVEL AND BAROMETRIC PRESSURE IS REDUCED BY ABOUT 3 kPa (.5 PSI) PER 1000 FEET OF ALTITUDE INCREASE.
b. If Fuse F1.26 is open, isolate any wiring concerns, repair as necessary and replace fuse.
c. If checks with Connector C4033 or wiring locate a fault, repair as necessary.
NOTE
IF NO CONCERN IS ISOLATED FOR THE ABOVE CONDITIONS, REFER TO THE APPROPRIATE 2005 ONLINE WORKSHOP MANUALS AND FOLLOW NORMAL DIAGNOSTICS.
WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited Warranty Coverage And Emissions Warranty Coverage
DEALER CODING
CONDITION
BASIC PART NO. CODE
14A488 30
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