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P3472 Cylinder 9 Exhaust Valve Control Circuit High GuideMechanic.Com As automotive technology becomes increasingly advanced, engines are equipped with complex management systems that help optimize fuel efficiency, emissions, and performance.
One such innovation is cylinder deactivation technology, which allows the engine to deactivate some cylinders under certain conditions to improve fuel economy.
However, like any sophisticated system, these components can occasionally experience faults. When the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects an issue, it logs a Diagnostic Trouble Code (DTC) to help identify and resolve the problem. P3472 is one such code, specifically pointing to a high voltage problem in the exhaust valve control circuit for cylinder 9.
In this article, we’ll explain what P3472 means, how the system works, what causes it, how to diagnose it, and how to fix it.
See Also: P3471 Cylinder 9 Exhaust Valve Control Circuit Low
P3472 Cylinder 9 Exhaust Valve Control Circuit High
What Is Code P3472?
Definition: P3472 – Cylinder 9 Exhaust Valve Control Circuit High
This code indicates that the ECM has detected an abnormally high voltage in the control circuit that operates the exhaust valve for cylinder 9.
In engines with cylinder deactivation, the ECM commands solenoids to activate or deactivate valve lifters using oil pressure. The proper voltage in the control circuit is crucial for correct valve operation.
A high voltage reading typically means that:
- The circuit has excessive voltage due to a short to power.
- There may be a malfunctioning ECM driver.
- The wiring is damaged or modified.
- The solenoid is failing in a way that causes high voltage readings.
How Cylinder Deactivation Works
Before we dive deeper into the fault, it’s important to understand how cylinder deactivation systems work.
Many modern V8 engines (like those used in General Motors vehicles) feature systems such as Active Fuel Management (AFM) or Displacement on Demand (DoD). Under light engine loads, some cylinders are deactivated by disabling their intake and exhaust valves.
Here’s a simplified process:
- The ECM commands oil pressure solenoids to redirect oil to special hydraulic lifters.
- These lifters collapse, preventing the valves from opening.
- When more power is needed, the system restores oil pressure to the lifters, allowing normal valve operation.
This process requires precise control of:
- Oil pressure and flow.
- Solenoid operation.
- Electrical circuits that manage solenoid activation.
If the voltage in the control circuit becomes too high, as with P3472, the ECM cannot properly control the exhaust valve for cylinder 9, which can affect engine performance and fuel economy.
P3472 Cylinder 9 Exhaust Valve Control Circuit High
Which Vehicles Are Affected?
DTC P3472 primarily affects vehicles equipped with V8 engines that use cylinder deactivation technology. The most common examples include:
- Chevrolet: Silverado, Tahoe, Suburban, Avalanche, Camaro
- GMC: Sierra, Yukon, Denali
- Cadillac: Escalade
Buick and other GM platforms using 5.3L, 6.0L, or 6.2L engines with AFM/DoD
While this article focuses on GM vehicles, similar systems exist in engines from other manufacturers, which may use different DTC designations.
Symptoms of P3472
The symptoms of P3472 can vary depending on the severity of the issue and whether the cylinder deactivation system is still partially operational. Common signs include: Illuminated Check Engine Light (CEL)
Rough Idle or Engine Misfires
When cylinder 9’s exhaust valve is not functioning properly.
Reduced Fuel Economy
The system may disable cylinder deactivation, causing higher fuel consumption.
Engine Performance Issues
Reduced power during acceleration.
Increased Emissions
Inefficient combustion leads to higher emissions output.
Engine Noises
Ticking, tapping, or knocking noises may occur if lifters or valves are not functioning correctly.
P3472 Cylinder 9 Exhaust Valve Control Circuit High
Causes of P3472
Several issues can trigger a high voltage condition in the exhaust valve control circuit. These include:
1. Faulty Exhaust Valve Control Solenoid (Cylinder 9)
A malfunctioning solenoid can cause excessive voltage readings in the circuit.
2. Short to Power
The control circuit may have a short to battery voltage or another power source, causing abnormally high readings.
3. Wiring Damage
Pinched, melted, or corroded wires can create unintended connections or voltage spikes.
4. Connector Problems
Loose, corroded, or damaged connectors may result in unstable voltage readings.
5. Faulty ECM Driver
The ECM’s internal driver that controls the solenoid may be malfunctioning and supplying excessive voltage.
6. Aftermarket Electrical Modifications
Improperly installed accessories or wiring changes may interfere with factory wiring, creating voltage irregularities.
P3472 Cylinder 9 Exhaust Valve Control Circuit High
Diagnosing Code P3472
A thorough diagnosis is essential to accurately pinpoint the problem. Here’s a step-by-step guide:
1. Verify the Code
Use an OBD-II scanner to verify that P3472 is present and check for related codes, such as:
P3469 (Circuit/Open)
P3470 (Circuit Performance)
P3471 (Circuit Low)
These codes can provide additional context.
2. Visual Inspection
Inspect the wiring harness and connectors for:
Frayed, pinched, or broken wires.
Corrosion at connector terminals.
Signs of burning or melting near heat sources.
3. Test Solenoid Resistance
Disconnect the solenoid connector for cylinder 9.
Use a digital multimeter to measure resistance.
Normal solenoid resistance usually ranges from 5–15 ohms.
Extremely low resistance may indicate an internal short.
4. Check Voltage Supply
With the ignition on, measure voltage at the solenoid connector.
Compare readings to manufacturer specifications.
5. Check for Shorts to Power
Inspect wiring for shorts to battery voltage or other power circuits.
Use a multimeter to check for continuity between power circuits and the solenoid control wire.
6. Test ECM Output
If wiring and solenoid test normal, check the ECM’s output using a scan tool or oscilloscope.
Abnormal output may point to ECM driver failure.
P3472 Cylinder 9 Exhaust Valve Control Circuit High
Repairing P3472
After diagnosis, appropriate repairs may include:
1. Replace the Exhaust Valve Control Solenoid
If faulty, replace the cylinder 9 solenoid with a high-quality OEM part.
2. Repair Wiring and Connectors
Replace or repair any damaged, shorted, or corroded wiring and connectors.
3. Correct Shorts to Power
Carefully trace wiring to eliminate any accidental connections to battery voltage or other power sources.
4. Replace or Repair ECM
If the ECM driver is faulty and supplying excessive voltage, reprogramming or ECM replacement may be required (rare).
5. Check and Clean Ground Connections
Ensure all ground connections related to the control circuit are secure and corrosion-free.
P3472 Cylinder 9 Exhaust Valve Control Circuit High
Preventing Code P3472
Proactive maintenance can help prevent DTC P3472:
Regular Oil Changes
Use manufacturer-recommended oil grades to ensure proper solenoid and lifter operation.
Inspect Wiring Routinely
Look for wiring damage during routine maintenance.
Avoid Electrical Modifications
Only install accessories that are compatible with your vehicle’s electrical system.
Address Warning Signs Early
Don’t ignore early symptoms like rough idle, ticking noises, or warning lights.
Keep Electrical Contacts Clean
Use dielectric grease to prevent corrosion in connectors.
Conclusion
DTC P3472 – Cylinder 9 Exhaust Valve Control Circuit High is a specific fault that points to excessive voltage in the circuit controlling the exhaust valve for cylinder 9.
This condition disrupts cylinder deactivation, affects performance, increases fuel consumption, and may cause long-term damage if left unaddressed.
Most common causes include wiring shorts to power, faulty solenoids, damaged connectors, or, less commonly, ECM failure. Systematic diagnosis involving visual inspection, resistance measurements, voltage testing, and ECM output checks is key to finding the root cause.
Timely repair not only restores performance but also ensures that the cylinder deactivation system operates efficiently, maximizing fuel savings and reducing emissions.
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