Ford F150 Pickup. Instruction — part 1493

Courtesy of FORD MOTOR CO.

Fig. 227: Identifying Brake Pedal Position Switch Circuits (All Others)
Courtesy of FORD MOTOR CO.

Testing

1) For KOER Only DTCs P0703 & P1703: Verify Brake Pedal Was Depressed
These DTCs indicate that when brake pedal was applied during KOER on-demand self-test, BPP signal
did not cycle high and low. Possible causes for this fault are:

z

Open Or Short In BPP Circuit

z

Open Or Short In Brakelight Circuit

z

Faulty Powertrain Control Module (PCM)

z

Faulty Rear Electronic Module (LS, Thunderbird & Windstar)

z

Faulty Lighting Control Module (Town Car)

z

Faulty BPP Switch

z

Misadjusted Brake Switch

z

Brake Pedal Not Applied During KOER On-Demand Self-Test

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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

If brake pedal was not applied and released during KOER on-demand self-test, repeat KOER ON-
DEMAND SELF-TEST. Depress and release brake pedal only once during test. If brake pedal was
applied and released during KOER on-demand self-test, proceed as follows:

z

On Town Car, diagnose Lighting Control Module (LCM) and/or related system. See SYSTEM
TESTS in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES & EQUIPMENT.

z

On Windstar, diagnose Rear Electronic Module (REM) and/or related system. See SYSTEM
TESTS in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES & EQUIPMENT.

z

On Expedition and Navigator, diagnose anti-lock brake system. See appropriate ANTI-LOCK
article in BRAKES.

z

On all others, go to step 3).

2) For KOEO Only DTCs P0703 & P1703: Verify Brake Pedal Was Not Applied
These DTCs indicate that BPP signal voltage was high during KOEO on-demand self-test. Possible
causes for these faults are:

z

Open Or Short In BPP Circuit

z

Open Or Short In Brakelight Circuit

z

Faulty Powertrain Control Module (PCM)

z

Faulty Rear Electronic Module (LS & Windstar)

z

Faulty Lighting Control Module (Town Car)

z

Faulty BPP Switch

z

Misadjusted Brake Switch

z

Brake Pedal Applied During Entire KOEO On-Demand Self-Test

If brake pedal was applied during KOEO on-demand self-test, repeat KOEO ON-DEMAND SELF-
TEST. DO NOT apply brake pedal during KOEO on-demand self-test. If brake pedal was not applied
during KOEO on-demand self-test, proceed as follows:

z

On Town Car, diagnose Lighting Control Module (LCM) and/or related system. See SYSTEM
TESTS in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES & EQUIPMENT.

z

On Windstar, diagnose Rear Electronic Module (REM) and/or related system. See SYSTEM
TESTS in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES & EQUIPMENT.

z

On Expedition and Navigator, diagnose anti-lock brake system. See appropriate ANTI-LOCK
article in BRAKES.

z

On all others, turn ignition switch to ON position and go to next step.

3) For Continuous Memory Only DTCs P0703, & For KOER & Continuous Memory Only DTC
P1572: Check Operation Of Brakelights
These DTCs indicate brake input rationality tests (one or both BPA or BPP switch inputs to PCM) failed
to change when expected. Possible causes are:

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

2003 Ford Pickup F150

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

z

Misadjusted Brake Switch

z

Blown Fuse

z

Faulty BPP Switch

z

Faulty BPA Switch

z

Open Or Short In BPP Circuit

z

Open Or Short In BPA Circuit

z

Faulty Powertrain Control Module (PCM)

Check operation of brakelights. If brakelights operate normally, go to next step. If brakelights do not
operate properly, on LS and Thunderbird, diagnose Rear Electronic Module (REM) and/or related system.
See SYSTEM TESTS in appropriate AUTOLAMP SYSTEMS article in ACCESSORIES &
EQUIPMENT. On all others, go to step 5) (brakelights inoperative), or step 7) (brakelights always on).

4) Check For PCM BPP PID Cycling

Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition
switch to ON position. Using scan tool, access BPP PID from PID/DATA MONITOR & RECORD
menu.

While observing BPP PID, apply and release brake pedal several times. If BPP PID does not cycle ON
and OFF, go to step 10). If BPP PID cycles ON and OFF, go to step 14) (for DTC P1572), or go to TEST
Z, step 1) (for all others).

5) Check B+ Voltage To BPP Switch

Ensure brakelight bulbs are okay. Disconnect BPP switch (located on brake pedal). Using a DVOM,
measure voltage between B+ circuit at BPP switch harness connector and chassis ground. If voltage is
more than 10 volts, go to next step. If voltage is 10 volts or less, check fuse for B+ circuit to BPP switch.
If fuse is okay, repair open in B+ circuit to BPP switch. If fuse is blown, repair short to ground in B+
circuit, BPP or brakelight PWR circuit. See EXTERIOR LIGHTS in SYSTEM WIRING DIAGRAMS in
ELECTRICAL.

6) Verify Integrity Of BPP Switch

Using a DVOM, measure resistance between appropriate BPP switch terminals. See Fig. 219-Fig. 227 .
Observe resistance measurement while applying brake pedal. If resistance is 5 ohms or more with brake
pedal applied, replace BPP switch. If resistance is less than 5 ohms with brake pedal applied, repair open
circuit between BPP switch and brakelight ground.

7) Verify BPP Switch Is Not Always Closed

Disconnect BPP switch (located on brake pedal). Turn ignition switch to ON position. If brakelights are
still illuminated, go to next step. If brakelights are now off, verify correct installation of BPP switch. If

NOTE:

If BPP PID is not accessible, go to step 10).

2003 Ford Pickup F150

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

installation is okay, replace BPP switch.

8) Check For Short To Power In PCM

Turn ignition switch to OFF position. Disconnect PCM connector(s). Turn ignition switch to ON position.
If brakelights are still illuminated, go to next step. If brakelights are now off, replace PCM.

9) Check Brakelight Circuit For Short To Power In Harness

Turn ignition switch to OFF position. Ensure PCM and BPP switch are disconnected. One at a time,
disconnect modules associated with brakelight circuit. See WIRING DIAGRAMS. After disconnecting
an associated module, turn ignition switch to ON position and check brakelights. Turn ignition switch to
OFF position. Repeat until each associated module has been disconnected or brakelights turn off. If
brakelights are still on after disconnecting all associated modules, repair short to power in brakelight
circuit. See EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If brakelights are off with
associated module(s) disconnected, diagnose appropriate module and/or related system. Repair system or
replace module as necessary.

10) Check For BPP Circuit Cycling

Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose,
damaged or corroded terminals. Repair as necessary. For Aviator, Explorer, LS, and Mountaineer (150-
pin PCM) with ABS-stability assist, measure DBA input at PCM harness connector and ground while
applying and releasing the brake. For all others, using a DVOM, measure voltage between BPP circuit at
PCM harness connector and chassis ground while applying and releasing brake pedal. If voltage does not
cycle, repair open in BPP circuit to PCM. If voltage cycles, go to next step (Aviator, Explorer, LS,
Mountaineer and Thunderbird), or replace PCM (all others).

11) Check For BPA Circuit Cycling

Ensure PCM connectors are disconnected. Using a DVOM, measure voltage between BPA circuit at PCM
harness connector and chassis ground while applying and releasing brake pedal. If voltage does not cycle,
go to next step. If voltage cycles, go to step 15).

12) Check BPA Circuit For Open In Harness

Disconnect BPA deactivator switch connector. Using a DVOM, measure resistance of BPA circuit
between PCM harness connector and BPA deactivator switch harness connector. See Fig. 219-Fig. 227 .
See WIRING DIAGRAMS. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or
more, repair open in BPA circuit between BPA switch and PCM.

13) Check BPA Deactivator Switch

Using a DVOM, measure resistance between BPA deactivator switch terminals while applying and
releasing brake pedal. With brake pedal applied, resistance should be more than 10 k/ohms. With brake
pedal released, resistance should be less than 5 ohms. If resistance is as specified, repair VPWR circuit to
BPA deactivator switch. If resistance is not as specified, replace BPA deactivator switch.

2003 Ford Pickup F150

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