Ford F150 Pickup. Instruction - part 1503

58) Check Fuel Injector Harness Resistance Between NG Module & Fuel Injector

Disconnect suspect fuel injector harness connector. Using a DVOM, measure resistance of injector and
VPWR circuits between suspect fuel injector harness connector and NG module harness connector. See
Fig. 235. If both resistance measurements are less than 5 ohms, go to next step. If any resistance
measurement is 5 ohms or more, repair open in affected circuit.

59) Check Fuel Injector Harness Circuit For Short To PWR Or Ground Between NG Module &
Injectors

Ensure suspect fuel injector harness connector is disconnected. Using a DVOM, measure resistance
between suspect injector circuit, and PWR GND and VPWR circuits at NG module harness connector.
See NG MODULE FUEL INJECTOR CIRCUIT TERMINAL IDENTIFICATION table. See Fig.
235. If any resistance measurement is 10 k/ohms or less, repair short between circuits. If all resistance
measurements are more than 10 k/ohms, go to step 61) (DTC P0172 or P0175), or replace faulty fuel
injector(s) (all others).

60) Check Fuel Injector Driver Signal
Ensure ignition switch is turned to OFF position. Connect NG module harness connector. Connect 12-
volt test light between injector and VPWR circuits at suspect fuel injector harness connector. While
cranking engine, observe test light. If test light does not glow dimly (no light or continuous bright light)
while cranking or running engine, go to next step. If test light glows dimly, PCM and NG module circuits
are okay. If engine runs rough, see ROUGH OR ROLLING IDLE, STALLS, MISSES,
HESITATION OR SURGE under SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG,
FLEX-FUEL & GASOLINE article. If engine is a no-start, go to TEST A, step 4). For all others, go to
step

64)

61) Check PCM Fuel Injector Harness Circuit Resistance

Ensure ignition switch is turned to OFF position. Ensure NG module and PCM harness connectors are
disconnected. Using a DVOM, measure resistance of VPWR circuit and injector circuits between PCM
harness connector and NG module harness connector. See PCM TO NG MODULE TERMINALS
table. See PCM CONNECTOR IDENTIFICATION and Fig. 235. If all resistance measurements are
less than 5 ohms, go to next step. If any resistance measurement is 5 ohms or more, repair open in
affected circuit.

PCM TO NG MODULE TERMINALS

NOTE:

A properly operating system will show a dim glow at idle on 12-volt test
light.

Application

PCM Terminal No.

NG Module Terminal No.

Fuel Injector No. 1

Fuel Injector No. 2

101

Fuel Injector No. 3

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

62) Check PCM Fuel Injector Circuit For Short To PWR Or GND In Harness

Using a DVOM, measure resistance between injector circuits, and PWR GND and VPWR circuits at
PCM harness connector. Using a DVOM, measure resistance between injector circuits, and CASE GND,
PWR GND and VPWR circuits at NG module harness connector. See PCM TO NG MODULE
TERMINALS table. See PCM CONNECTOR IDENTIFICATION and Fig. 235. If any resistance
measurement is 10 k/ohms or less, repair short between affected circuits. If all resistance measurements
are more than 10 k/ohms, go to step 64) (DTCs P0172 and P0175), or go to next step (all others).

63) Check Fuel Injector Driver Signal From PCM

Ensure ignition switch is turned to OFF position. Connect PCM harness connector. Ensure NG module is
disconnected. Connect 12-volt test light between VPWR circuit and each fuel injector signal circuit from
PCM at NG module harness connector. See Fig. 235. Crank engine and observe test light. If test light
does not glow dimly or flicker, replace PCM. If test light glows dimly or flickers, engine runs okay or
you were directed here for DTCs, go to next step. If test light glows dimly or flickers and engine is a no-
start, replace NG module. If test light glows dimly or flickers and engine runs rough, diagnose by
symptom. See ROUGH OR ROLLING IDLE, STALLS, MISSES, HESITATION OR SURGE under
SYMPTOMS in TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE article.

64) Check Fuel Injector Flow & Leakage

Turn ignition switch to OFF position. Reconnect all connectors. Connect scan tool to Data Link
Connector (DLC). Install electronic Natural Gas Injector Tester found in Natural Gas Tool Kit (134-
00114) to suspect fuel injector. Follow injector tester instructions and specifications. Turn ignition switch
to ON position. Using scan tool, access FRP PID (if available) from PID/DATA MONITOR & RECORD
menu. Record initial FRP sensor PID or fuel pressure gauge reading. Using scan tool, access pulse width
of 200 milliseconds. Activate fuel injector tester. Record final FRP sensor PID or fuel pressure gauge
reading. Subtract final FRP sensor PID or fuel pressure gauge reading from the initial reading to calculate
pressure drop. Repeat test procedures for all injectors. If fuel injector flow or leakage rate is not within
specification, replace defective fuel injector(s). If flow rate or leakage is within specification for each fuel
injector, proceed as follows:

If directed here for DTCs P0171, P0172, P0174 and P0175, fault is unable to be duplicated at this
time. Go to TEST Z, step 1).

If directed here for DTCs P1130 and P1150, go to step 66).

For all others, go to next step.

Fuel Injector No. 4

100

Fuel Injector No. 5

Fuel Injector No. 6

Fuel Injector No. 7

Fuel Injector No. 8

PWR GND

24, 51, 76, 77 & 103

40 & 60

VPWR

71 & 97

37 & 57

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

65) Check Cylinder Compression

Using compression gauge, check compression on all cylinders. Record cylinder compressions. Cylinder
compressions should be higher than 75 percent of highest cylinder compression reading. If a cylinder's
compression is not within specification, repair engine as necessary. If all cylinder compressions are
within specification, go to next step (DTCs P1130, P1131, P1150, P1151, P2195 and P2197), or go to
step 71) (DTCs P1132, P1152, P2196 or P2198).

66) Check HO2S Integrity

Turn ignition switch to OFF position. Inspect HO2S and wiring harness for chafing, damage and
contamination from oil, water, coolant, etc. Repair as necessary. If no visible concerns are found, start
engine and operate at 2000 RPM for 2 minutes. Using scan tool, perform KOER ON-DEMAND SELF-
TEST. Turn ignition switch to OFF position. If DTC P1131, P1151, P2195 and/or P2197 is present, go to
next step. If DTC P1131, P1151, P2195 and/or P2197 is not present, HO2S system is functioning
properly at this time. Faults cannot be duplicated or identified at this time. Go to TEST Z, step 1).

67) Check HO2S Ability To Generate A Voltage More Than .5 Volt
Turn ignition switch to OFF position. Disconnect suspect HO2S harness connector. Using a DVOM,
measure voltage between HO2S SIG circuit, and SIG RTN or HO2S GND circuits at HO2S connector.
See Fig. 233. Start engine and operate at 2000 RPM for 2 minutes. Repeat KOER ON-DEMAND
SELF-TEST while monitoring HO2S voltage. If voltage measurement is more than .5 volt during, or at
end of test, go to next step. If voltage measurement stays at .5 volt or less during test, replace HO2S.

68) Check HO2S SIG & SIG RTN Circuits For Open In Harness

Turn ignition switch to OFF position. Disconnect PCM connector. Disconnect suspect HO2S harness
connector. Inspect both ends of connector for loose, damaged or corroded terminals. Repair as necessary.
Using a DVOM, measure resistance of HO2S SIG and SIG RTN circuits between PCM harness connector
and suspect HO2S harness connector. See NGV HO2S PCM TERMINAL IDENTIFICATION table.
See PCM CONNECTOR IDENTIFICATION and Fig. 233. If both resistance measurements are less
than 5 ohms, go to next step. If either resistance measurement is 5 ohms or more, repair open in affected
circuit.

69) Check HO2S Circuit For Short To Ground In Harness

Using a DVOM, measure resistance of HO2S SIG circuit between PCM harness connector and negative
battery terminal. See NGV HO2S PCM TERMINAL IDENTIFICATION table. See PCM
CONNECTOR IDENTIFICATION and Fig. 233. If resistance is more than 10 k/ohms, go to next step.
If resistance is 10 k/ohms or less, repair short to ground in HO2S SIG circuit.

70) Check HO2S Circuit For Short To Ground

Using a DVOM, measure resistance between suspect HO2S SIG circuit, and PWR GND or SIG RTN

NOTE:

Vacuum or air leaks can cause DTCs P1130, P1131, P1150, P1151, P2195
and P2197 to set.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

circuits at PCM harness connector. If either resistance measurement is 10 k/ohms or less, replace HO2S.
If both resistance measurements are more than 10 k/ohms, proceed as follows:

For DTCs P1130 and P1150, go to next step.

For Continuous Memory DTCs P1131, P1151, P2195 and P2197, go to step 76).

For KOER DTCs P1131, P1151, P2195 and P2197, replace PCM.

71) Check For DTCs P1132, P1152, P2196 & P2198 With P1130 & P1150

Perform KOER ON-DEMAND SELF-TEST. If DTC P1132, P1152, P2196 or P2198 is present, go to
next step. If DTC P1132, P1152, P2196 or P2198 is not present, fault is unable to be duplicated at this
time. Go to TEST Z, step 1).

72) Check HO2S SIG Circuit For Short To VPWR & VREF
DTCs P1130, P1132, P2196 (HO2S-11) and/or P1150, P1152, P2198 (HO2S-21) indicate HO2S is
always rich. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position.
Using scan tool, access appropriate HO2S PID for DTC retrieved. If HO2S PID voltage is more than one
volt and less than 4 volts, go to next step. If HO2S PID voltage is not as specified, go to step

75)

73) Check HO2S Circuit For Short To VPWR

Turn ignition switch to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged
or corroded terminals. Repair as necessary. Disconnect suspect HO2S connector. Using a DVOM,
measure resistance between HO2S SIG and VPWR circuits at suspect HO2S harness connector. See Fig.
233. If resistance measurement is more than 10 k/ohms, reconnect PCM and go to next step. If resistance
measurement is 10 k/ohms or less, repair short to VPWR.

74) Check HO2S SIG For Short To HO2S HTR Circuit In Sensor
Ensure scan tool is connected to DLC. Ensure suspect HO2S is disconnected. Turn ignition switch to ON
position. Using scan tool, access HO2S PID for DTC retrieved. If HO2S PID voltage is less than .2 volt,
replace internally shorted HO2S. If HO2S PID voltage is .2 volt or more, replace PCM.

75) Attempt To Generate DTCs P1131, P1151, P2195 & P2197

Disconnect suspect HO2S connector. Connect a jumper wire between HO2S SIG circuit at HO2S harness
connector and negative battery terminal. See Fig. 233. Perform KOER ON-DEMAND SELF-TEST. If
DTC P1131, P1151, P2195 or P2197 is present, remove jumper wire and go to next step. If DTC P1131,
P1151, P2195 or P2197 is not present, disconnect and inspect PCM connector and harness connector
terminals and repair as necessary. If PCM connector and harness connector terminals are okay, replace
PCM.

76) HO2S Voltage Check

NOTE:

HO2S may be displayed on scan tool as O2S.

NOTE:

HO2S may be displayed on scan tool as O2S.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

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