Code
P07B3
Generic
P — Powertrain
Transmission Park Position Sensor/Switch A Circuit Low
Views:
UK: 16
EN: 25
RU: 15
AI status
Completed
Completed
100%
Causes
- Short to ground on the Park position sensor/switch A signal wire
- Open or damaged wiring harness or chafed insulation touching ground
- Corroded or loose connector at the sensor or PCM
- Faulty park position sensor/switch (internal short or stuck closed contact)
- PCM or body control module internal fault (less common)
- Water or contamination in connector causing low resistance to ground
Symptoms
- Malfunction Indicator Lamp (MIL) or transmission warning lamp illuminated
- Vehicle may not start (won't crank) if PCM cannot detect Park/Neutral
- Transmission stuck in Park or fails to shift properly
- Incorrect PRNDL display or gear indicator
- Intermittent no-start or unexpected neutral/park behavior
- Stored trouble code and possible limp-home mode
What to check
- Read and record freeze frame and live data for transmission range/park switch
- Visual inspection of transmission range/park switch connector and wiring for damage, corrosion, or water intrusion
- Backprobe the Park A signal with a DVOM while moving shift lever through positions
- Check for proper reference voltage (5V) at the PCM and pull-up on the signal circuit
- Check continuity to ground and to the PCM pin (with ignition off)
- Wiggle test wiring while monitoring signal to detect intermittent faults
Signal parameters
- PCM reference voltage: typically 5.0 V (verify vehicle spec)
- Expected Park A signal: near 0 V (ground) when switch closed in Park, ≈4.5–5.0 V when open (other positions)
- Circuit Low condition: signal stuck near 0–0.5 V across all gear positions
- Switch resistance: near 0 Ω when closed (Park), open/infinite when open (verify with service manual)
- Typical pull-up resistor built into PCM or module; measure with sensor disconnected to confirm pull-up to reference voltage
Diagnostic algorithm
- Retrieve codes and freeze frame; verify P07B3 is current and note conditions (ignition state, gear position).
- Visually inspect the transmission-range/park switch connector and wiring for damage, corrosion, or moisture; repair obvious issues.
- With key ON (engine off) backprobe the Park A signal at the sensor connector and at the PCM connector. Verify PCM reference/pull-up voltage present at PCM with sensor connected and disconnected.
- Operate the shift lever through all positions while observing the Park A signal. Confirm expected transition: low (≈0 V) in Park, high (≈5 V) in other positions. If signal remains low in all positions, suspect short to ground.
- If low in all positions, disconnect the sensor and measure continuity between the signal wire and chassis ground. A direct short (near 0 Ω) indicates wiring short or pin contact; repair wiring.
- If no short to ground when sensor disconnected but signal still low at PCM, suspect internal PCM fault or poor PCM connector terminal—inspect and repair connector pins and retest.
- If wiring and PCM check good, bench-test or replace the park position sensor/switch and re-test. Confirm new sensor produces correct voltages/resistances.
- After repair, clear codes, perform functional test and road test to verify the DTC does not return and that Park/Neutral detection and starting behavior are normal.
Likely causes
- Connector corrosion at transmission-range/park switch
- Broken or pinched signal wire shorted to chassis ground
- Faulty park position sensor/switch A (internal failure)
- Poor mating pin at PCM or bent terminal creating low resistance path
- Aftermarket accessories or improper repairs that damaged wiring
Fault status
Status
Circuit Low on Transmission Park Position Sensor/Switch A: PCM detects the Park A signal at low voltage (shorted or stuck to ground) when it should be high in non-Park positions or varying with gear selection.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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Code
P07B3
LAND ROVER
P — Powertrain
Transmission Park Position Sensor A - Low Circuit
Views:
UK: 8
EN: 9
RU: 5
AI status
Completed
Completed
100%
Causes
- Short to ground on the Park position sensor/switch A signal wire
- Open or damaged wiring harness or chafed insulation touching ground
- Corroded or loose connector at the sensor or PCM
- Faulty park position sensor/switch (internal short or stuck closed contact)
- PCM or body control module internal fault (less common)
- Water or contamination in connector causing low resistance to ground
Symptoms
- Malfunction Indicator Lamp (MIL) or transmission warning lamp illuminated
- Vehicle may not start (won't crank) if PCM cannot detect Park/Neutral
- Transmission stuck in Park or fails to shift properly
- Incorrect PRNDL display or gear indicator
- Intermittent no-start or unexpected neutral/park behavior
- Stored trouble code and possible limp-home mode
What to check
- Read and record freeze frame and live data for transmission range/park switch
- Visual inspection of transmission range/park switch connector and wiring for damage, corrosion, or water intrusion
- Backprobe the Park A signal with a DVOM while moving shift lever through positions
- Check for proper reference voltage (5V) at the PCM and pull-up on the signal circuit
- Check continuity to ground and to the PCM pin (with ignition off)
- Wiggle test wiring while monitoring signal to detect intermittent faults
Signal parameters
- PCM reference voltage: typically 5.0 V (verify vehicle spec)
- Expected Park A signal: near 0 V (ground) when switch closed in Park, ≈4.5–5.0 V when open (other positions)
- Circuit Low condition: signal stuck near 0–0.5 V across all gear positions
- Switch resistance: near 0 Ω when closed (Park), open/infinite when open (verify with service manual)
- Typical pull-up resistor built into PCM or module; measure with sensor disconnected to confirm pull-up to reference voltage
Diagnostic algorithm
- Retrieve codes and freeze frame; verify P07B3 is current and note conditions (ignition state, gear position).
- Visually inspect the transmission-range/park switch connector and wiring for damage, corrosion, or moisture; repair obvious issues.
- With key ON (engine off) backprobe the Park A signal at the sensor connector and at the PCM connector. Verify PCM reference/pull-up voltage present at PCM with sensor connected and disconnected.
- Operate the shift lever through all positions while observing the Park A signal. Confirm expected transition: low (≈0 V) in Park, high (≈5 V) in other positions. If signal remains low in all positions, suspect short to ground.
- If low in all positions, disconnect the sensor and measure continuity between the signal wire and chassis ground. A direct short (near 0 Ω) indicates wiring short or pin contact; repair wiring.
- If no short to ground when sensor disconnected but signal still low at PCM, suspect internal PCM fault or poor PCM connector terminal—inspect and repair connector pins and retest.
- If wiring and PCM check good, bench-test or replace the park position sensor/switch and re-test. Confirm new sensor produces correct voltages/resistances.
- After repair, clear codes, perform functional test and road test to verify the DTC does not return and that Park/Neutral detection and starting behavior are normal.
Likely causes
- Connector corrosion at transmission-range/park switch
- Broken or pinched signal wire shorted to chassis ground
- Faulty park position sensor/switch A (internal failure)
- Poor mating pin at PCM or bent terminal creating low resistance path
- Aftermarket accessories or improper repairs that damaged wiring
Fault status
Status
Circuit Low on Transmission Park Position Sensor/Switch A: PCM detects the Park A signal at low voltage (shorted or stuck to ground) when it should be high in non-Park positions or varying with gear selection.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
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0
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