I have the repeating (after erased numerous times, but no symptoms) P1400 code for 1998 Nissan Pathfinder 3.3, 164,000 miles. It was throwing this same code with an older motor, and still is with replacement motor installed last week. I have 12v at the wire plug when it's unplugged and key on. 12v applied with jumper wires actuates the solenoid on both its leads. But, when I have a helper turn key to on I cannot hear or feel the solenoid activating. Is this solenoid controlled by ECU giving it a ground? Or how?

The following is from service manual page EC-365. Could be a wire issue. Check out step 3 of diagnostic procedure. https://www.nicoclub.com/service-manual ... 8%2Fec.pdf

Thanks. With key on I tested the solenoid plug for 12v, I connected a lead to each terminal and got +12v.. I reversed them and got -12v. I think this is telling me that I have a full-time short in that wire to ground, because as I understand it, the ECM should connect.the ground wire to its ground to activate the solenoid and allow vacuum to pass through the EGR system. As-is. my solenoid apparently has an energized state all the time because it has a full-time ground connection on its plug, when it should be switched to ground by the ECM as-needed. So I think as-is, it is not activating the EGR ports at all. Does thisake sense?

Either the wire, or the driver output in the ECM is blown. The drivers are MOSFET's, so it's not uncommon for them to blow short instead of open. Ohm to ground with both ends of the wire disconnected, that will tell you if the problem is in the wire or the ECM. If the wire reads infinity to ground when disconnected, the ECM is faulty.

Thanks I'll find the wire at the ECM and try this. Now to locate the ECM. I'm sure that's easy to find, and hopefully easy enough to access.

Before that I'll ohm test plug ground wire with car off and ignition on, just to see what that shows. Maybe it opens the ground when on.

You don't need to find the wire at the ECM end, just disconnect the ECM and then ohm the wire to ground at the solenoid end. The object is simply to have both ends of the wire unhooked, so you're only measuring the wire's integrity and not any attached device.

1998 Pathfinder 3.3L, automatic, 164,000 miles, stock. Runs real good.

So I'm having a recurring P1400 EGRC Solenoid Valve error come back after erasing codes. It reappears almost immediately after being erased. I don't have any operability issues. No other codes but one that came up after I started running the motor with the solenoid plug disconnected (for testing)...P0443 Evap Emission Purge Control Valve Circuit. But it stopped appearing after I reconnected the solenoid plug.

I looked where the ECM is to access the EGRC Solenoid ground wire and crap is that a pain to get out! So I did these troubleshooting steps to test the Ground wire resistance and the Voltage at the plug wire instead. This is after I tested the valve clicks/opens with 12v injected from a jumper wire. The solenoid appears good, as far as activating manually.

Ground Wire tests: left socket when looking at plug with lock button on top.

ENGINE COLD --
Off cold: 500 ohms
Key on cold: 1,200 ohms
Cranked idle Cold: 3,600 ohms.

ENGINE HOT --
25 minute idle warm up and short drive, and RPM revs to 3,000.
Off: 500 ohms.
Key On: 1,200 ohms
Cranked at 850-rpm idle: 1,600 ohms before revving, 3,400 ohms after revving 2,000 rpm.
Cranked and held at 2,000 rpm (in Neutral) for 60 seconds: 1,850 ohms.


### VOLTAGE tests ###
Power Wire: right socket.

Using ground wire on solenoid plug (motor cold) --
Off: 0.01v
Key On: 11.9v
Cranked: 14.3v

Using chassis ground frame bolt (motor hot) --
Off: 0.07v
Key on: 12.4v
Cranked: 13.7v
- Battery terminal as ground had same results.

If nobody knows I'm just gonna ignore it because I dont have emissions tests here and it shows no driveability issues either, so likley unimportant.

But I kinda wanted to understand if my EGR is being left open to exhaust or closed, with the signal from the solenoid as-is. Anyone know by chance?

Thanks!

YleKyote wrote: ↑

Thu Aug 31, 2023 6:12 pm

The solenoid appears good, as far as activating manually.

Ground Wire tests: left socket when looking at plug with lock button on top.

Power Wire: right socket.

Using ground wire on solenoid plug (motor cold) --
Off: 0.01v
Key On: 11.9v
Cranked: 14.3v

Using chassis ground frame bolt (motor hot) --
Off: 0.07v
Key on: 12.4v
Cranked: 13.7v
- Battery terminal as ground had same results.

If nobody knows I'm just gonna ignore it because I dont have emissions tests here and it shows no driveability issues either, so likley unimportant.

But I kinda wanted to understand if my EGR is being left open to exhaust or closed, with the signal from the solenoid as-is. Anyone know by chance?

Thanks!

The solenoid may seems like it works, and maybe it does, because you hear the solenoid actuate when your apply battery power with jumpers as indicated in the last test of the diagnostic procedure I posted from the service manual. However, that means nothing for certain if you did check for air flow between ports A and B as well as A and C during powered and not powered states. This will confirm whether or not the valve is functioning correctly as this test is intended.

When you have the vehicle running and you don't hear the solenoid actuate that's no surprise because it is intended to actuate only under specific conditions. I would not just assume it does not work when the engine is running, maybe it doesn't or maybe you are not catching it at the time it does open, if it does.

For the output signal test, procedure 3 (your ground test) you have to get the ECM harness connector disconnected. Otherwise, the Ohm readings you are getting are meaningless. As Vstar said, when it is disconnected you can check plug pin 1 for resistance to body ground. There should be absolutely no continuity when the ECM harness is disconnected. Is the is continuity, you have a short to ground in that wire.

For the power supply test, procedure 1 (your voltage test with ground to battery), the voltage should be exactly the same as the battery voltage. If it is not, there is a short in this wire.

If the solenoid is never actuating and actually opening when it should when the engine is running, then there will be no exhaust gases being recirculated. However, unless you test the valve for air flow as indicated in the procedure then you will not know if it is stuck open or stuck closed or functioning as it should if the power and signal tests pass, which you won't know until you do those tests right.

If the EGR valve is failing mechanically or electrically, it's an easy fix as a replacement. If you have a short circuit in the wiring causing the problem, that's a red flag in my book to keep a fire extinguisher handy or just wait for something else to fail because of this short if you ignore it. Emissions tests be damned.

If it's the ECM causing the issue as Vstar mentioned it could be, doing those test right will confirm it if all the tests pass. The ECM harness is a pain to disconnect but so be it. Gotta git-r-done.

Thanks. I keep a fire extinguisher in all rigs! Lol Will function check the solenoid this weekend.

I don't know how you're ohming the circuit with the engine running and power applied, that's meaningless (and can blow up your meter). The only things that matter are that the solenoid coil isn't shorted, the Blue/White wire has integrity, and the ECM driver works and has integrity. This isn't rocket science. Ohm the solenoid coil, if it's something reasonable that isn't near zero then it's okay. Power the solenoid and make sure the orifice goes from blocked to passing. Ohm the wire disconnected from the ECM and it should read infinity. If all of those things are true then your ECM is bad. Screwing around just because the ECM is a pain to get at is just going to leave you writing long posts and scratching your head over what should be a simple diagnosis.