2001 Dodge Ram 1500 4x4 P/U 5.9L - Persistent P0443 Code After Purge Valve Replacement

The key term in the code description is 'CIRCUIT'. Please check fuses first. Is there 12V present on the dark blue/white wire (power)? Is the signal wire (pink/white) open, grounded, or showing voltage between the purge valve and PCM? Confirm these readings—specifically: 12V at dkblu/wht, and voltage status on pnk/wht.

I measured 12V on the dark blue/white wire. However, only 6V is present on the pink/white signal wire.

Let's confirm by unplugging the purge valve connector. There should be 12V on the dark blue/white wire and no voltage (or zero) on the signal wire (pink/white)—this wire must remain open, not grounded or energized. Check for corrosion in the electrical connectors. Was this a brand-new purge valve installed?

Yes, the purge valve was replaced with a new one.

Where could voltage be coming from on the pink wire? Is it being supplied by the PCM or another component?

First, confirm these basic readings. Then proceed to inspect the wiring circuit between the purge valve and the PCM. Vehicle history may help—such as recent pump replacement or added lights—which could be contributing factors.

The check engine light has been on for months. I only recently started investigating due to an emissions test requirement for registration renewal. Initially, the issue was intermittent; now it's constant. No new parts have been added or installed. The leak detection pump has not been replaced.

We need to determine where the pink wire is shorted to voltage—especially since only 6V is present, which is concerning. Try unplugging the PCM's gray connector and check if the wire from the purge valve connects directly to pin 20 at the PCM. Also, verify whether your OBD-II scanner shows additional codes such as P1494 or P1495.

I tested continuity between pin 20 on the gray PCM connector and the purge valve—no breaks were found. When I measured the pink/white wire at the valve, I read only 3.9VDC instead of 6V.

Should there be any voltage on the pink/white signal wire under normal conditions?

Are you absolutely certain you're measuring at the purge valve terminal, not a downstream point?

Yes, I am probing directly on the purge valve.

I'm considering jumping the pink/white wire from the purge valve directly to pin 20 at the PCM to rule out a short in the wiring. Does this wire run straight from the purge valve to pin 20, or does it pass through another sensor first?

The wiring diagram shows a direct connection from the purge valve to the PCM—circuit #K52. This confirms no intermediate sensors are involved.

I previously replied but deleted it—revisiting your earlier suggestions. Back-probe the pink/white wire at the purge solenoid while the key is on, engine off. What voltage do you read? Use the battery negative terminal as ground for your multimeter. Do you have an ohmmeter? Check the relay coil resistance—it should be between 30–40 ohms. The purge solenoid may use pulse-width modulation (PWM), so a reading of 6V could indicate normal PWM operation. Are you measuring voltage with the key on engine off or when running?

I haven't had time to work on the vehicle recently. I jumped the pink/white wire directly from the purge valve to pin 20 at the PCM. The code still returns after two ignition cycles. Any further ideas?

I don't see the PCM commanding a purge cycle when the engine is off. With key on, engine off (KOEO), what voltage do you read on the pink/white wire? Confirm that it's actually 6V. Re-read earlier suggestions—especially Joe’s request to check the ohm resistance of the purge solenoid (30–40 ohms). KOEO = Key On, Engine Off.

With key on engine off (KOEO), back-probing both the pink/white and blue wires shows 13.6VDC to ground.

This reading—13.6V to ground on both wires—is abnormal and suggests a possible short circuit or grounding issue in the signal path, especially since it occurs at KOEO when no purge command should be active.