Ford F150 Pickup. Manual — part 1582

Fig. 365: Identifying Instrument Cluster Module Harness Connector C220c Terminals
Courtesy of FORD MOTOR CO.

TEST TG: 4X4 LOW RANGE

Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used
to diagnose the following:

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Electronic shift control module and mechanical 4WD LOW wiring harness circuit (4WD LOW).

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Powertrain Control Module (PCM).

NOTE:

After each service or repair procedure has been completed, reconnect all
components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-
V systems are working properly and DTCs are no longer present.

NOTE:

Electronic shift control module is also referred to as Generic Electronic Module
(GEM).

2003 Ford Pickup F150

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

4-WHEEL DRIVE SHIFT CONTROL MODULE

Testing

1) For KOEO Only DTC P1781: Verify 4x4L Switch Position
DTC P1729 is set when PCM receives too high of a voltage on 4WD LOW circuit when 4x4L switch is
ON (indicating open or short in 4WD switch circuit). DTC P1781 indicates 4x4L switch position closed
during QUICK TEST. Possible causes are:

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4WD LOW Circuit Open Or Shorted

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Faulty Electronic Shift Control Module

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Faulty Powertrain Control Module (PCM)

Ensure vehicle is equipped with 4WD. If switch was not in 2WD or 4WD HIGH position during KOEO
self-test, select 2WD or 4WD HIGH and repeat QUICK TEST. If switch position was as specified, go to
next step.

2) Check 4WD LOW Circuit For Intermittent Fault

Connect scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool,
access 4x4L PID from PID/DATA MONITOR & RECORD menu. Cycle 4x4L switch to 2WD. Check
for indication of fault while performing the following:

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Shake, wiggle and bend small sections of wiring harness starting at transfer case working toward
PCM.

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Lightly tap on transfer case harness connector.

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Shake, wiggle and bend small sections of wiring harness starting at instrument cluster working
toward PCM.

A fault will be indicated by 4x4L PID value changing from OFF to ON. If any faults are found, isolate
fault and repair as necessary. If no faults are found, go to next step.

3) Check 4WD LOW Signal Voltage To PCM

Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector(s) for loose,
damaged or corroded terminals. Repair as necessary. Turn ignition switch to ON position. While cycling

Application

Location

Explorer & Mountaineer

Under Passenger's Side Of Dash, Near Center Console

Expedition & Navigator

Under Driver's Side Dash, Near Left Kick Panel

F150 Pickup

Under Driver's Side Of Dash, Near Steering Column

Ranger

Behind Right Kick Panel

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

Transmission Range (TR) sensor must indicate Neutral before shifting into
4WD LOW.

2003 Ford Pickup F150

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

4x4L switch, measure voltage between negative battery terminal and 4WD LOW circuit at PCM harness
connector. See WIRING DIAGRAMS. If voltage cycles with 4x4L switch position, replace PCM. If
voltage does not cycle with 4x4L switch position, go to next step.

4) Check 4WD LOW Circuit For Open In Harness

Turn ignition switch to OFF position. Disconnect electronic shift control module. See 4-WHEEL
DRIVE SHIFT CONTROL MODULE table. Inspect connector for loose, damaged or corroded
terminals. Repair as necessary. On electronic shift models, measure resistance of 4WD LOW circuit
between PCM harness connector and electronic shift control module harness connector. See WIRING
DIAGRAMS. On mechanical shift models, measure resistance of 4WD LOW circuit between PCM
harness connector, instrument cluster and 4x4L switch. See WIRING DIAGRAMS. If all resistances are
5 ohms or less, go to next step. If any resistance is more than 5 ohms, repair open in 4WD LOW circuit.

5) Check 4WD LOW Circuit For Short To PWR Or GND In Harness

Reconnect electronic shift control module. Using a DVOM, measure resistance between 4WD LOW
circuit, and VPWR circuit at PCM harness connector and negative battery terminal. If both resistance
measurements are more than 10 k/ohms, 4WD LOW circuit is okay. Check transfer case for mechanical
fault. See appropriate DIAGNOSIS or OVERHAUL article in TRANSFER CASES for further diagnosis.
If either resistance measurement is 10 k/ohms or less, repair short in 4WD LOW circuit.

TEST TH: REVERSE SWITCH

Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used
to diagnose the following:

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Reverse Switch

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Wiring Harness Circuits (RS & SIG RTN)

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Powertrain Control Module (PCM)

Testing

1) For Continuous Memory Only DTC P0812: Check Reverse Switch Function
DTC P0812 is set when PCM senses high voltage on RS circuit when voltage should be low. Possible
causes are:

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Gearshift Lever Not In Neutral While Performing KOEO Self-Test

NOTE:

After each service or repair procedure has been completed, reconnect all
components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-
V systems are working properly and DTCs are no longer present.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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

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RS Circuit Shorted To B+ Or VPWR

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Faulty RS Switch

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RS Circuit Open Or Shorted To SIG RTN

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Faulty Powertrain Control Module (PCM)

Ensure gearshift lever is in Neutral during KOEO self-test. Turn ignition switch to OFF position. Connect
scan tool to Data Link Connector (DLC). Turn ignition switch to ON position. Using scan tool, access RS
PID from PID/DATA MONITOR & RECORD menu. Move gearshift lever in and out of Reverse. If RS
PID does not change from ON to OFF with gearshift lever movement, go to next step. If RS PID value
changes from ON to OFF with gearshift lever movement, concern is intermittent. Disconnect PCM
connector(s). Inspect connector for loose, damaged or corroded terminals. Repair as necessary. If
connector and terminals are okay, replace PCM.

2) Check RS Switch Resistance

Disconnect RS switch connector. RS switch is located near shift linkage. Inspect switch and bracket for
damage. Repair as necessary. Using a DVOM, measure resistance between RS switch terminals with
gearshift lever in Reverse. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or
more, replace RS switch.

3) Check RS Circuit For Open In Harness

Turn ignition switch to OFF position. Disconnect scan tool from DLC. Disconnect PCM connector(s).
Using a DVOM, measure resistance of RS and SIG RTN circuits between PCM harness connector and
RS switch harness connector. See WIRING DIAGRAMS. If both resistances are less than 5 ohms, go to
next step. If either resistance is 5 ohms or more, repair open in affected circuit.

4) Check RS Circuit For Short To SIG RTN Or Chassis Ground In Harness

Using a DVOM, measure resistance between RS circuit, and SIG RTN circuit at PCM harness connector
and chassis ground. If both resistances are more than 10 k/ohms, replace PCM. If either resistance is 10
k/ohms or less, repair RS circuit for short to chassis ground or SIG RTN.

TEST TJ: OUTPUT SHAFT SPEED SENSOR

Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used
to diagnose the following:

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Output Shaft Speed (OSS) Sensor

NOTE:

After each service or repair procedure has been completed, reconnect all
components. Clear DTCs and repeat QUICK TEST procedures to ensure all EEC-
V systems are working properly and DTCs are no longer present.

2003 Ford Pickup F150

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