Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2006 Mercury Mariner 4WD V6-3.0L VIN 1FACTORY OEM SERVICE PROCEDURE
Test I: Flash Code 4 - Clutch/Neutral Switch Circuit Failure
PINPOINT TEST I: FLASH CODE 4 - CLUTCH/NEUTRAL SWITCH CIRCUIT FAILURE
Normal Operation
When the speed control actuator carries out the self-test, it checks for continuity to ground through circuit 199 (LB/YE). This is accomplished by sending a voltage reference signal to the clutch pedal position (CPP) switch (manual transaxle) or the transmission range (TR) sensor (automatic transaxle).
When the clutch is applied, the signal is routed through circuit 359 (GY/RD) to the powertrain control module (PCM). The PCM provides an internal ground.
When the automatic transaxle is in NEUTRAL, the signal is routed through circuit 57 (BK) to ground.
Possible Causes
- Circuit 57 (BK) open
- Circuit 199 (LB/YE) open
- Circuit 359 (GY/RD) open
- CPP switch
- TR sensor
- Speed control actuator
- PCM
I1-I2:
I2-I4:
I5-I7:
Normal Operation
When the speed control actuator carries out the self-test, it checks for continuity to ground through circuit 199 (LB/YE). This is accomplished by sending a voltage reference signal to the clutch pedal position (CPP) switch (manual transaxle) or the transmission range (TR) sensor (automatic transaxle).
When the clutch is applied, the signal is routed through circuit 359 (GY/RD) to the powertrain control module (PCM). The PCM provides an internal ground.
When the automatic transaxle is in NEUTRAL, the signal is routed through circuit 57 (BK) to ground.
Possible Causes
- Circuit 57 (BK) open
- Circuit 199 (LB/YE) open
- Circuit 359 (GY/RD) open
- CPP switch
- TR sensor
- Speed control actuator
- PCM
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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