Section 17-01: Lighting, Exterior | 1996 F-150, F-250, F-350, F-Super Duty Motorhome and Bronco Workshop Manual |
DIAGNOSIS AND TESTING
Pinpoint Tests — Backup Lamps
NOTE: Use Rotunda 73 Digital Multimeter 105-R0051 or equivalent when performing electrical pinpoint tests.
PINPOINT TEST X: BACKUP LAMPS INOPERATIVE
X1 CHECK SUPPLY AT BACKUP LAMP SWITCH
Is battery voltage present?
X2 CHECK SUPPLY AT FUSE 5 (15A)
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent, check output side of power distribution box fuse 5 (15A) for voltage.
Is battery voltage present?
| Yes | No |
|---|
| SERVICE Circuit 298 (P/O) for open circuit. RESTORE vehicle. RETEST system. | GO to X3. |
X3 CHECK SUPPLY TO FUSE 5 (15A)
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent check input side of fuse 5 (15A).
Is battery voltage present?
| Yes | No |
|---|
| REPLACE damaged power distribution box fuse 5 (15A). RESTORE vehicle. RETEST system. | SERVICE Circuit 687 (GY/Y) for open circuit. RESTORE vehicle. RETEST system. |
X4 CHECK BACKUP LAMP SWITCH, PARK/NEUTRAL POSITION SWITCH OR TRANSMISSION RANGE (TR) SENSOR
- Shift transmission shift control selector lever and housing to the REVERSE position.
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent connected to ground, check circuit 140 (BK/PK) for voltage.
Is battery voltage present?
| Yes | No |
|---|
| GO to X5. | REPLACE damaged backup lamp switch (manual transmission) or park/neutral position switch or transmission range (TR) sensor (automatic transmission). RESTORE vehicle. RETEST system. |
X5 CHECK SUPPLY TO BACKUP LAMPS
- Gain access to backup lamps.
- Disconnect backup lamp miniature bulb.
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent connected to a known good ground, check Circuit 140 (BK/PK) for voltage.
Is battery voltage present?
| Yes | No |
|---|
| GO to X6. | SERVICE Circuit 140 (BK/PK) for open circuit. RESTORE vehicle. RETEST system. |
X6 CHECK BACKUP LAMP GROUND
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent connected to a known good ground, connect second lead to Circuit 57 (BK) at backup lamp socket.
- Measure resistance.
Is resistance 5 ohms or less?
| Yes | No |
|---|
| REPLACE damaged backup lamp miniature bulb. RESTORE vehicle. RETEST system. | SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system. |
PINPOINT TEST Y: INDIVIDUAL BACKUP LAMPS INOPERATIVE
Y1 INDIVIDUAL BACKUP LAMP CHECK
- Gain access to backup lamps.
- Disconnect backup lamp miniature bulb.
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent connected to a good ground, check Circuit 140 (BK/PK) for voltage.
Is battery voltage present?
| Yes | No |
|---|
| GO to Y2. | SERVICE Circuit 140 (BK/PK) for open circuit. RESTORE vehicle. RETEST system. |
Y2 INDIVIDUAL BACKUP GROUND CHECK
- Using Rotunda 73 Digital Multimeter 105-R0051 or equivalent connected to a good ground.
- With the second lead probe the Circuit 57 (BK) at backup lamp socket.
- Measure the resistance.
Is resistance 5 ohms or less?
| Yes | No |
|---|
| REPLACE damaged backup lamp miniature bulb. RESTORE vehicle. RETEST system. | SERVICE Circuit 57 (BK) for open circuit. RESTORE vehicle. RETEST system. |
PINPOINT TEST Z: BACKUP LAMPS ON CONTINUOUSLY
Z1 BACKUP LAMP CIRCUIT CHECK
- Gain access to backup lamp switch connector.
- With vehicle in neutral or park.
- Disconnect backup lamp switch connector, or park/neutral position switch connector or transmission range (TR) sensor connector.
Do the backup lamps go out?
| Yes | No |
|---|
| REPLACE damaged backup lamp switch or park/neutral position switch or transmission range (TR) sensor. RESTORE vehicle. RETEST system. | SERVICE short circuit to 140 (BK/PK). RESTORE vehicle. RETEST system. |