Ford F150 Pickup. Instruction — part 1475

cannot be identified at this time. If TP V PID voltage does not increase smoothly during throttle
movement, turn ignition switch to OFF position and replace TP sensor.

TEST DJ: AIR CONDITIONING EVAPORATOR TEMPERATURE SENSOR

Diagnostic Aids

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following:

z

Air Conditioning Evaporative Temperature (ACET) Sensor

z

Wiring Harness Circuits (ACET & SIG RTN)

z

Powertrain Control Module (PCM)

DTC P1437 is set when ACET signal is more than self-test maximum of 4.5 volts. DTC P1436 is set when
ACET signal is less than self-test minimum of .13 volt.

ACET SENSOR SPECIFICATIONS

(1)

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:

ACET sensor may also be referred to as an Evaporator Air Discharge
Temperature (EADT) sensor.

Temperature °F (°C)

Volts

Ohms

-4 (-20)

4.66

276,960

14 (-10)

4.45

160,310

32 (0)

4.14

95,850

50 (10)

3.73

58,990

68 (20)

3.26

37,340

86 (30)

2.74

24,250

104 (40)

2.23

16,110

122 (50)

1.77

10,930

140 (60)

1.37

7550

158 (70)

1.05

5340

176 (80)

.80

3840

194 (90)

.61

2800

212 (100)

.47

2080

(1)

Value may vary by 15 percent due to sensor and VREF variations. Voltage values are calculated for
5.0 volts VREF.

2003 Ford Pickup F150

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

Fig. 188: Identifying ACET Sensor Circuits & Connector Terminals (Sable & Taurus)
Courtesy of FORD MOTOR CO.

Fig. 189: Identifying ACET Sensor Circuits & Connector Terminals (All Other)
Courtesy of FORD MOTOR CO.

Testing

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

If a scan tool communication concern exists, remove jumper wire and go

2003 Ford Pickup F150

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

1) For KOEO & KOER Only DTCs P0538 & P1437: Simulate Opposite Signal To PCM
DTC P0538 or P1437 is set when ACET signal is more than self-test maximum of 4.5 volts. Possible
causes for this fault are:

z

ACET Circuit Open Or Shorted To VREF

z

SIG RTN Circuit Open To ACET Sensor

z

Faulty ACET Sensor

z

Faulty Powertrain Control Module (PCM)

Disconnect ACET sensor connector. Connect a jumper wire between ACET and SIG RTN circuits at
ACET sensor harness connector. See Fig. 188 or Fig. 189 . Repeat KOEO or KOER self-test where DTC
P0538 or P1437 was received.

If DTC P0537 or P1436 is received during self-test, replace ACET sensor. If DTC P0537 or P1436 is not
received during self-test, turn ignition switch to OFF position, remove jumper wire and go to next step.

2) Check ACET & SIG RTN Circuits For Open In Harness

Disconnect PCM connector(s). Using a DVOM, measure resistance of ACET and SIG RTN circuits
between PCM harness connector and ACET sensor harness connector. If both resistance measurements
are less than 5 ohms, replace PCM. If either resistance measurement is 5 ohms or more, repair open in
affected circuit.

4) Check ACET Circuit For Short To VREF In Harness

Turn ignition switch to OFF position. Disconnect PCM connector(s). Using a DVOM, measure resistance
between ACET and VREF circuits at PCM harness connector. If resistance measurement is more than 10
k/ohms, replace PCM. If resistance is 10 k/ohms or less, repair short between ACET and VREF circuits.

5) For KOEO & KOER Only DTCs P0537 & P1436: Simulate Opposite Signal To PCM
DTC P0537 or P1436 is set when ACET signal is less than self-test minimum of .13 volt. Possible causes
for this fault are:

z

ACET Circuit Shorted To GND Or SIG RTN

z

Faulty ACET Sensor

z

Faulty Powertrain Control Module (PCM)

Disconnect ACET sensor connector. Repeat KOEO or KOER self-test where DTC P0538 or P1437 was
received. If DTC P0538 or P1437 is received, replace ACET sensor. If DTC P0538 or P1437 is not

to step 4).

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 2) to step 4). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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

received, go to next step.

6) Check ACET Circuit For Short To Ground In Harness

Disconnect PCM connector(s). Using a DVOM, measure resistance between ACET and SIG RTN circuits
at ACET sensor harness connector. Also, measure resistance between ACET circuit at ACET sensor
harness connector and ground. If both resistance measurements are more than 10 k/ohms, replace PCM. If
either resistance measurement is 10 k/ohms or less, repair short in affected circuit.

10) For Continuous Memory Only DTCs P0537, P0538, P1436 & P1437: Check ACET & SIG RTN
Circuits For Intermittent Concerns
Disconnect ACET sensor connector. Using a DVOM, measure voltage between ACET and SIG RTN
circuits at ACET sensor harness connector. Turn ignition switch to ON position. While monitoring
voltage reading on DVOM, shake, wiggle and bend small sections of wiring harness while working
toward PCM. Voltage should be a constant 4.5-5.5 volts. Voltage reading will change suddenly when a
fault is detected.

Turn ignition switch to OFF position. Inspect associated connectors for damage. If there is any change in
voltage reading, or if a concern is found, isolate fault and repair as necessary. If no faults are indicated,
concern is intermittent and cannot be identified at this time. Go to TEST Z, step 1).

TEST DK: ELECTRONIC THROTTLE CONTROL & ACCELERATOR PEDAL POSITION SENSOR

Description

The normal range of the throttle angle measurement for the throttle position ETC (APP) sensor is 0 to 17
degrees. For voltage ranges of each sensor see Fig. 190.

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips
from step 6) to step 10). No test procedures have been omitted.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

For DTC P1436, a sudden change could indicate a short to GND. For DTC
P1437, a sudden change could indicate an open ACET or SIG RTN circuit.

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