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  • P0499 -NLVD Canister Vent Valve Solenoid Circuit High

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Repair Questions and Answers.

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 #395288  by In-trepid
 
One of my 2002 300m Specials has a P0499 error. It will reset but comes back as soon as the engine starts. Looking up the error code in the Factory Powertrain Diagnostic procedures manual, it basically points me in the direction of the NVLD assembly (which I believe is the assembly located above the gas tank), wiring to the unit, or a PCM problem. I have never seen this error before and generally see the more prevalent P044X - P045X type errors which almost always points to a bad NVLD assembly. I am looking for three things to help with eliminating this error.
1. If anyone has had this error and successfully eliminated it, what was the cause?
2. What section/page in the 8W section of the Factory Service Manual shows the wiring schematic for the NVLD system?
3. What is the procedure to troubleshoot this without having a DRBlll?

I'm inclined to believe that the NVLD assembly is bad. If possible, I would like to verify this prior to spending $150 for a new assembly and dropping the gas tank. This is somewhat urgent as the car is due for its emissions inspection soon and they won't let me get a new registration without the emissions certification.
User avatar
 #395289  by FIREM
 
Quick shooting from the hip, I would start with the meter test for NVLD in the KB :

P0499 is more likely the purge vent solenoid (I think)
Reading high, coming back immediately leads me to suspect open ground.
User avatar
 #395295  by FIREM
 
I do believe that it is 02 and up. 01 and down near the air cleaner plumbing.
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 #395296  by In-trepid
 
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I found this at 8W-30-16 in the FSM. It appears that there is an NVLD Solenoid Control and an NVLD Switch Sense wire plus the ground. I assume that the solenoid control wire is in the same connector with the switch sense wire under the back seat. This should allow me to test the solenoid coil (WT/DG wire) at 7.5 to 8.5 ohms as referenced in the Powertrain Diagnostics Procedures and also test the NVLD switch (orange wire) As well as the ground (black wire) at the same connector without removing the NVLD module.

Before removing the fuel tank, I'll replace the purge valve as I have one of those in my spares. I will also pull C3 on the PCM and check that out. Easy things first.
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 #395302  by FIREM
 
Double check the wire diagram in use. NVLD System 02 and up does not use a Leak Detection Pump that was used in the 01 and down vehicles.
Hence the Natural Volatile Leak Detection name.
“This method of leak detection is based on the "Ideal Gas" law that states, in part, that the pressure in a sealed vessel will change linearly as a function of the temperature of the gas in that vessel. Any loss of seal will allow the internal pressure to equalize with the atmospheric pressure outside the container”
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 #395306  by In-trepid
 
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The original diagram is from my pdf version 2003 FSM. It is the same in the 2002 hard copy FSM. In the 2004 FSM they re-label it as Natural Vacuum Leak Detection Assembly. This diagram is from the 2004 hard copy FSM. All of the wiring appears to be the same. I guess Chrysler was a little slow in updating the FSM with the correct nomenclature.
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 #395309  by In-trepid
 
After a couple of quick tests of the NLVD circuit, I have come to the conclusion that I have a bad NLVD assembly. I tested from plug C308 under the back seat. I suppose that I could still have a plug that is bad on the NLVD assembly itself, but I'm going to order the Standard Motor Products CP3147 Fuel Vapor Canister from Amazon as I have 30 days to return it if it doesn't fix the problem.

https://www.amazon.com/gp/product/B005B ... ZAGX&psc=1

1. I tested the ground wire on the plug to a ground point - 0 ohms - good
2. Following the test procedure in the Powertrain Diagnostic Procedures, I tested across the solenoid pin 3 to pin 1- open - should be 7.5 to 8.5 ohms - bad

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 #395337  by In-trepid
 
My Standard Motor Products CP3147 Fuel Vapor Canister from Amazon arrived today. With all of the obvious signs, I would guess that it is a genuine Mopar part. 

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 #395338  by M-Pressive
 
Every one of those that I have ever ordered was oem.

Hopefully it solves the problem.
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 #395339  by In-trepid
 
New one measures 8.3 ohms across the solenoid. Old one in the car is open. I'm 99% sure it will fix the problem.
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 #395362  by Sneke_Eyez
 
Good find on the testing procedure. They're not exactly a joy to do, but run the tank down low and it becomes much easier!
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 #395366  by LUNAT1C
 
Hopefully I don't jinx myself (or John, for that matter) by saying so, but after dropping the tank on the Jeep (twice) for the cracked fuel pump, I'm thinking dropping the tank on an LH should comparatively be a breeze... 21 gallon tank that is 3 football fields long, squeezed between the frame and rear control arms, and encased in a steel skid plate from head to toe. My current herniated disc issue is giving me flashbacks to nearly throwing out my back on that one... but at least the full steel skidplate made it easy to use my floor jacks to let it down and hoist it back up without denting the plastic tank. Still had to drag and wiggle it out from under the Jeep and give my neighbors a sight. Yes, running the Jeep until the low fuel light came on, then running it another 20+ miles was instrumental!

I've only needed to support the empty tank on my Special so far to replace the rusty straps, no other issues... YET. Where's some wood to knock on...
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 #395413  by In-trepid
 
Well, we found the reason for the NLVD canister solenoid error. The critters seem to have gnawed on the wires! Hard to see real well in the pictures, but there are some bare wires and probably one that's gnawed through. I'm having a shop do the work as I don't want to lay on the cold ground and do it myself. Probably the old unit isn't bad, but they need to drop down the tank to repair the wires and since this piece seems to cause a lot of errors as these cars get older and since I have a new unit in hand, I made the decision to replace it anyway. It should buy a few years of peace of mind from any NLVD errors and the price is basically the same for labor if it gets replaced or not.

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 #395433  by Sneke_Eyez
 
Ugh, those darn critters! At least you know it will get fixed up!
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 #395435  by M-Pressive
 
Is this my old car or a different one?