Test Ff: Parking Brake Applied 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.

1) KOER DTC P1536: Perform BRAKE Warning Light Bulb Check
DTC P1536 indicates that PCM does not detect a PBA state change during KOER ON-DEMAND SELF-TEST. Possible causes are:
- Low Brake Fluid
- Short To Ground Or Voltage
- Open Circuit
- Faulty Powertrain Control Module (PCM)
Start engine and observe BRAKE warning light (bulb check). If BRAKE light illuminates, turn ignition off and go to next step. If BRAKE light does not illuminate, repair wiring in bulb circuit(s) as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repair is completed, perform bulb check again to confirm repair.

2) Check For Brake System Concern

Ensure parking brake is fully released. Turn ignition on. Check BRAKE warning light. If BRAKE light is illuminated, a fault exists in brake system. Check and repair brake system as necessary. See appropriate DISC & DRUM article in BRAKES. If BRAKE light is off, go to next step.

3) Check PBA PID

Ensure scan tool is connected to Data Link Connector (DLC). Using scan tool, access PBA PID from PID/DATA MONITOR & RECORD menu. Apply and release parking brake pedal fully several times, while observing PBA PID reading. If PBA PID reading indicates ON only, leave ignition on, scan tool in PID/DATA MONITOR & RECORD mode and go to next step. If PBA PID reading does not indicate ON only, leave ignition on, scan tool in PID/DATA MONITOR & RECORD mode and go to step 6).

4) Check PBA Switch Failed Closed

While observing PBA PID, disconnect PBA switch. Switch is located on top of parking brake pedal. If PBA PID reading changes from ON to OFF, replace PBA switch. Clear DTCs and retest. If PBA PID does not change from ON to OFF, go to next step.

5) Check For Short To Ground

Turn ignition off. Disconnect PCM connector. PCM is located in left rear of engine compartment, near brake master cylinder. Ensure PBA switch is disconnected. Using DVOM, measure resistance between chassis ground and specified PBA signal circuit at test pin No. 5 at breakout box. See PBA SIGNAL CIRCUIT WIRE IDENTIFICATION table. See Figure-Figure . If resistance is less than 10 k/ohms, repair short to ground in PBA signal circuit between PBA switch and PCM, Generic Electronic Module (GEM), or instrument cluster. If resistance is 10 k/ohms or more, check for short to ground at terminal No. 5 at PCM connector. Repair as necessary, reconnect all connectors and go to step 9).

PBA SIGNAL CIRCUIT WIRE IDENTIFICATION

Application	Wire Color
Econoline	Violet/White
Excursion & F250-550	Light Green/Red
F650-750	Tan/Red

6) Check PBA PID

While observing PBA PID, apply and release parking brake pedal fully several times. If PBA PID reading indicates OFF only, turn ignition off and go to next step. If PBA PID reading cycles between OFF and ON, fault may be intermittent. Leave ignition on, scan tool in PID/DATA MONITOR & RECORD mode and go to step 10).

7) Check PBA Switch For Failed Open

Disconnect PBA switch. Switch is located on top of parking brake pedal. Connect a jumper wire between chassis ground and specified PBA signal circuit at PBA switch harness connector. See PBA SIGNAL CIRCUIT WIRE IDENTIFICATION table. See Figure-Figure . Turn ignition on. Using scan tool, access PBA PID from PID/DATA MONITOR & RECORD menu. If PBA PID reading indicates ON, replace PBA switch. Clear DTCs and retest. If PBA PID reading indicates OFF, go to next step.

8) Check PBA Signal 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. Using DVOM, measure resistance of PBA signal circuit between PBA switch harness connector and test pin No. 5 at breakout box. If resistance is 5 ohms or more, repair open in PBA signal circuit. Clear DTCs and retest. If resistance is less than 5 ohms, PBA signal circuit is okay. Reconnect all connectors, clear DTCs and retest. Go to next step to confirm repair.

9) Confirm PCM Fault

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

10) Check For Intermittent Short To Ground

Disconnect PBA switch. PBA PID reading should indicate OFF. While observing PBA PID, wiggle and bend small sections of wiring harness working from PBA switch toward PCM. If fault is indicated (PBA PID changes to ON), isolate short to ground and repair as necessary. Clear DTCs and retest. If no fault is indicated, go to next step.

11) Check For Intermittent Open

Connect jumper wire between chassis ground and PBA switch harness connector. PBA PID should now indicate ON. While observing PBA PID reading, wiggle and bend small sections of wiring harness working from PBA switch toward PCM. If fault is indicated (PBA PID changes to OFF), isolate open circuit and repair as necessary. Clear DTCs and retest. If no fault is indicated, no concern is indicated at this time. Clear DTCs and retest.