Test FD: Brake Pedal Position Switch: Testing

WARNING: This page is about a different variant/trim than selected.

NOTE: For additional testing information, see DIAGNOSTIC AIDS .

NOTE: When performing KOER SWITCH TEST, wait 5 seconds after pressing "Trigger" to start test before running through driver operated controls. Test may take up to 5 minutes to complete.

NOTE: When selecting PID for brake pedal position switch, if BPP PID is not available, select BOO PID. No BPP/BOO PID transition indicates a CPP/NSS circuit fault.

1) KOER DTC P0703: Check BPP/BOO PID
DTC P0703 indicates brakelight switch circuit malfunction. Possible causes for this fault are:
- BPP Circuit Open, Or Shorted To Ground Or PWR
- BPP PWR Circuit Open Or Shorted To Ground
- Faulty BPP Switch
- Faulty Harness Connector
- Faulty PCM
Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access BPP/BOO PID from PID/DATA MONITOR & RECORD menu. Turn ignition on. While observing PID, firmly apply and release brake pedal several times. If PID reading indicates ON only, leave ignition on, scan tool in PID/DATA MONITOR & RECORD mode and go to next step. If PID reading does not indicate ON only, leave ignition on, scan tool in PID/DATA MONITOR & RECORD mode and go to step 4).

2) Check BPP Switch Failed Closed

Disconnect BPP switch connector. Switch is located at top of brake pedal and has a 2-pin connector (Econoline and F650-750 with air brakes) or 5-pin connector (Excursion and F250-750 with hydraulic brakes). If BPP/BOO PID reading changes to OFF, replace BPP switch. If PID reading does not change to OFF, go to next step.

3) Check For Short To Voltage In Switch Output Circuit

Turn ignition off. Disconnect PCM connector. PCM is located in left rear of engine compartment, near brake master cylinder. Turn ignition on. Using DVOM, check for battery voltage between chassis ground and specified output circuit at BPP switch harness connector. For wire colors, see BPP OUTPUT CIRCUIT WIRE IDENTIFICATION table. See Figure-Figure . If battery voltage is present, repair short to voltage in appropriate BPP output circuit. If battery voltage is not present, check for short to battery voltage at terminal No. 92 at PCM connector. Repair as necessary, reconnect all connectors and go to step 11).

BPP OUTPUT CIRCUIT WIRE IDENTIFICATION

Application	Wire Color
Econoline & F650-750 W/Air Brakes	Light Green
Excursion & F250-750 W/Hydraulic Brakes	Red/Light Green

4) Check BPP/BOO PID

While observing BPP/BOO PID reading, apply and release brake pedal several times. If BPP/BOO PID reading indicates OFF only, go to next step. If BPP/BOO PID cycles between OFF and ON, fault is intermittent. Leave scan tool connected to DLC and go to step 12).

5) Check Fuse

Turn ignition off. Remove and inspect BPP PWR feed circuit fuse from central junction box (Econoline, Excursion and F250-750 with hydraulic brakes), or battery junction box (F650-750 with air brakes). Central junction box is located behind lower left side of instrument panel. Battery junction box is located on left front of engine compartment. See Figure-Figure . If BPP PWR feed circuit fuse is okay, check for open BPP output circuit. Leave fuse removed and go to step 8). If fuse is blown, go to next step.

6) Check BPP PWR Feed Circuit For Short to Ground

Ensure ignition is off. Disconnect BPP switch connector. Switch is located at top of brake pedal and has a 2-pin connector (Econoline and F650-750 with air brakes) or 5-pin connector (Excursion and F250-750 with hydraulic brakes). Using DVOM, measure resistance between chassis ground and specified BPP PWR feed circuit at BPP switch harness connector. See BPP PWR FEED CIRCUIT WIRE IDENTIFICATION table. See Figure-Figure . If resistance is less than 10 k/ohms, repair short to ground in appropriate BPP PWR feed circuit between BPP switch and central junction box or battery junction. Replace fuse, clear DTCs and retest. If resistance is 10 k/ohms or more, go to next step.

BPP PWR FEED CIRCUIT WIRE IDENTIFICATION

Application	Wire Color
Econoline & F650-750 W/Air Brakes	Light Green/Red
Excursion & F250-750 W/Hydraulic Brakes	Light Blue/Black

7) Check BPP Output Circuit For Short To Ground

Ensure ignition is off. Disconnect PCM connector. PCM is located in left rear of engine compartment, near brake master cylinder. Using DVOM, measure resistance between chassis ground and specified BPP output circuit at BPP switch harness connector. See BPP OUTPUT CIRCUIT WIRE IDENTIFICATION table. See Figure-Figure . If resistance is less than 10 k/ohms, repair short to ground in appropriate BPP output circuit. Clear DTCs and retest. If resistance is 10 k/ohms or more, check for short to ground at terminal No. 92 at PCM connector. Repair as necessary, reconnect all connectors and go to step 11).

8) Check BPP PWR Feed Circuit For Open

Turn ignition off. Disconnect BPP switch connector. Switch is located at top of brake pedal and has a 2-pin connector (Econoline and F650-750 with air brakes) or 5-pin connector (Excursion and F250-750 with hydraulic brakes). Using DVOM, measure resistance of BPP PWR feed circuit between BPP switch harness connector and output side of BPP PWR fuse. If resistance is less than 5 ohms, reinstall BPP PWR feed circuit fuse and go to next step. If resistance is 5 ohms or more, repair open in appropriate BPP PWR feed circuit between BPP switch and central junction box (Econoline, Excursion and F250-750 with hydraulic brakes), or battery junction box (F650-750 with air brakes). Clear DTCs and retest.

9) Check For Open BPP Switch

Ensure BPP PWR feed circuit fuse is reinstalled and BPP switch is disconnected. Turn ignition on. Connect a jumper wire between BPP PWR feed circuit and BPP output circuit at BPP switch harness connector. See Figure-Figure . Using scan tool, select BPP/BOO PID from PID/DATA MONITOR & RECORD menu. If PID reading indicates ON, replace BPP switch. Clear DTCs and retest. If PID reading still indicates OFF, remove jumper wire and go to next step.

10) Check BPP Output Circuit For Open

Turn ignition off. Disconnect PCM connector and inspect for damaged pins, corrosion and loose wires. PCM is located in left rear of engine compartment, near brake master cylinder. Repair connector as necessary. Install Rotunda Breakout Box (014-00950), leaving PCM disconnected. Turn ignition on. Using DVOM, measure resistance of BPP output circuit between BPP switch harness connector and test pin No. 92 at breakout box. If resistance is less than 5 ohms, reconnect all connectors and go to next step. If resistance is 5 ohms or more, repair open in BPP output circuit between PCM and BPP switch. Clear DTCs and retest.

11) Confirm PCM Fault

Turn ignition on. Using scan tool, access BPP/BOO PID from PID/DATA MONITOR & RECORD menu. While observing PID, firmly apply and release brake pedal. If PID reading cycles between ON and OFF, no concern is indicated at this time. Clear DTCs and retest. If PID reading does not cycle between ON and OFF, replace PCM. Clear DTCs and retest.

12) Check For Intermittent Open Or Short Circuit

Turn ignition off. Ensure BPP switch is disconnected. Turn ignition on. Connect a jumper wire between BPP PWR feed circuit and BPP output circuit at BPP switch harness connector. Using scan tool, access BPP/BOO PID from PID/DATA MONITOR & RECORD menu. Ensure BPP/BOO PID reading on scan tool indicates ON and brakelights are also on. While observing BPP/BOO PID, wiggle and bend small sections of wiring harness starting at BPP switch connector and working toward PCM. If no fault is indicated (PID reading does not change to OFF), leave scan tool in PID/DATA MONITOR & RECORD mode and go to next step. If fault is indicated (PID reading changes to OFF), isolate fault in wiring harness and repair as necessary. Clear DTCs and retest.

13) Check For Intermittent Short To Voltage

Remove BPP PWR feed circuit fuse from central junction box (Econoline, Excursion and F250-750 with hydraulic brakes), or battery junction box (F650-750 with air brakes). Central junction box is located behind lower left side of instrument panel. Battery junction box is located on left front of engine compartment. Confirm BPP/BOO PID reading on scan tool indicates OFF and brakelights are also off. While observing PID, wiggle and bend small sections of wiring harness starting at BPP switch connector and working toward PCM. If fault is indicated (PID changes to ON), isolate fault in wiring harness and repair as necessary. Clear DTCs and retest. If no fault is indicated, fault is intermittent and cannot be duplicated at this time. Clear DTCs and retest.