P0443 Code in 2004 Dodge Caravan: Diagnosing Purge Solenoid Wiring or PCM Issue

Which engine? Likely the 3.3L. The evaporative purge solenoid has two wires: DB/WT (power) and DB/BR (return). With the connector unplugged during KOEO, the DB/WT wire should have 12 volts — is that correct? The DB/BR wire should be a constant ground — is it grounded? You claim no voltage when disconnected — first check the wiring. If those conditions are met, verify 12V at the PCM's C3 connector (pin #20), which controls the purge solenoid. Also note: no other codes exist beyond these, and there’s no remote starter. The vehicle has 193k miles. Where is the PCM located? I’ll check voltage there.

Confirmed 3.3L engine. Wires are blue with green tracer and black with green tracer. During KOEO, both wires show no voltage — they appear grounded. No other issues beyond P0441 and P0446 that appear after a while. No remote starter. Vehicle has 193k miles. I suspect the PCM might be faulty — but I’ll first verify power at the PCM connector (C3) before concluding anything.

The C3 connector is the third from the left on the PCM. At KOEO, with the solenoid disconnected and the harness unplugged from the PCM, pins 20 and 29 show no voltage. Neither wire is grounded at this point — both are floating.

This is a power-side switch circuit. Voltage is only applied by the PCM when it decides to activate the purge solenoid. During cold or hot start delays, the PCM does not energize the solenoid — no vapors are purged during this time. The proportional purge solenoid operates at 200 Hz and is controlled by an engine controller circuit that monitors current flow to adjust purge rate. Most issues stem from a faulty purge solenoid — check resistance with a multimeter. A common failure mode is an open circuit, which would show up as a lack of signal or no voltage.

The PCM provides power on one wire and monitors current flow through the solenoid to detect faults — this internal sensing circuit helps identify problems. The return wire is a constant ground. If the purge solenoid shorts, the PCM will shut down its driver circuit to protect itself from damage.

My colleague is correct — but I think TMI right now. When the PCM is unplugged, we must determine whether the wires are grounded or shorted to a voltage source. This will help distinguish between a wiring fault and a faulty PCM. The advice given often relies on workarounds — diagnosing without a high-end scan tool with bi-directional control and manufacturer-specific software is risky.

Both wires are grounded when the solenoid is unplugged and in KOEO. Zero resistance between the two wires or to ground — regardless of key position. I'm confused by the wire colors: they're DB/Green and Black/Green, not the standard DB/White and Black/White.

Unplug both the PCM and the purge solenoid to test if the grounding occurs at the wiring or inside the PCM. Wiring is more likely than a faulty internal driver. As for wire colors — they vary by model year, production batch, and revisions. My manuals are from older editions, color fading, and I have color blindness all contribute to confusion. Always use a digital multimeter (DVOM) for safety and accuracy.

Neither wire shows voltage at the PCM connector when tested with the solenoid disconnected.

I used a test light. With the battery positive connected, and the purge solenoid unplugged but the PCM connected, touching each terminal one at a time during KOEO (key on, engine off), both terminals lit up — indicating power is present. This suggests the issue may not be with the PCM driver. I also found that Alldata shows the C3 connector has pins 20 (DB/White) for purge control and pin 29 (DB/Black) as return — a constant ground. The color mismatch is confusing. I’d like to know if your VIN ends in 'R'? Did you replace the solenoid? Did you test the coil resistance? A used scan tool from eBay can be affordable, and replacing a PCM is expensive — especially if not needed.

Today, P0441 appeared along with P0443. This suggests a developing evaporative system issue that may be related to the purge solenoid or vapor canister.

Thanks, Joe. I used a test light connected to battery positive and probed each terminal at the solenoid connector (with PCM connected) during KOEO — both terminals lit up. So both wires have power. This confirms that the issue isn’t with the wiring or voltage source. I also found an Alldata schematic showing standard wire colors: DB/White and Black/White. The green tracers are confusing — could this be a model year variation? I’m still unsure.

The test was performed with the solenoid disconnected, PCM connector connected, key on engine off, using a test light to battery positive. Test resistance of the purge solenoid coil and report back. Don’t worry about P0441 until this is resolved — it’s related but secondary. If the solenoid shorted out, it may have damaged the PCM driver circuit. Best way to verify the PCM driver: use a test light connected to battery negative, probe the control wire at the solenoid with the PCM disconnected, and command the scan tool to activate the purge solenoid — if the test light lights up, the driver is working. PCMs are expensive — don’t guess. Check wire colors next to each other on both sides. Are any of the PCM connector colors correct? What’s your 8th digit in the VIN? R? Model: Regular or Grand Caravan? ES/XE/SXT?

If both terminals light with a test light, unplug the PCM and check if the control wire still lights up. If it goes out — that indicates a shorted PCM driver. If not — then there’s a ground fault in the wiring between the PCM and solenoid. Confirming a bad PCM driver requires both a test light and a scan tool with bi-directional controls. If the driver is faulty, the solenoid is likely also defective. I asked about VIN because my friend uses Mitchell on Demand 5 to check for color variations across model years.