EVAP problem

MNJSITORIUS

MEMBER
2000 DODGE RAM
5.9L
V8
4WD
AUTOMATIC
187,692 MILES

I have a code re recurring p0443. I have changed my purge solenoid and checked all my vacuum lines. But I must have a short somewhere in my electrical or my PCM. I have traced as much wire as I can have found no breaks. Also tested my connector once to ground with engine off and only got 6.8 volts. But with it plugged in and running both sides of the plug read about 13.4v. So I am at a loss because it is running really rich and it is my only vehicle.

Tuesday, September 26th, 2017 AT 8:43 AM

1 Reply

STEVE W.

MECHANIC
15,233 POSTS

Do you have access to a scan tool with bi-directional control? With that you could command the valve on/off and see if the ECM actually responds and controls the valve.

It is a duty cycle valve that the PCM pulses to purge the system. You will not get accurate readings using a VOM with the engine running because of that, you actually need a scope to watch the pulse train and determine if the system is working.

You should have one side, dark blue with white stripe, with battery voltage with the key on engine off. That is fed from fuse 11. The other side, pink with white stripe, is the control side and pulsed to ground by the ECM.

What you can do to test and see if voltage is the problem would be to run a jumper from the dark blue/white wire to a switched battery source.

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Tuesday, September 26th, 2017 AT 10:29 AM