Chrysler guys Explain Difference btwn leak detection pump
#1160637
01/19/12 12:31 PM
01/19/12 12:31 PM
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Joined: Jan 2006
Posts: 587
IL . usa
cjs69mope
OP
mopar
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OP
mopar
Joined: Jan 2006
Posts: 587
IL . usa
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Hello I was wondering if any Chrysler technicians can explain why does Chrysler call their Evap emissions valve a leak detection pump ?
I have many years of foreign car experiance and most manufacturers call their evap valve a canister close valve.
I was just wondering this because i was working on a 2004 dodge caravan and was wondering why the three wires to the valve? One must be a sense input but don't have a diagram . most of the foreign cars have a two wire so testing is easy just supply ground to close or open it and you can pressure test the system . Any info would be great thanks .
Last edited by cjs69mope; 01/19/12 12:37 PM.
1969 Dodge Charger
1969 Dodge Superbee
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: cjs69mope]
#1160638
01/19/12 02:07 PM
01/19/12 02:07 PM
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Joined: Aug 2008
Posts: 286
Catskill, NY
teflon
enthusiast
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enthusiast
Joined: Aug 2008
Posts: 286
Catskill, NY
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Pin 1 is ground, pin2 is NVLD switch signal and pin 3 is NVLD solenoid control. NVLD stands for natural vacuum leak detection. As the vehicle cools, the fuel tank naturally contracts creating a vacuum on a seal container. When this occurs the switch closes in the NVLD signaling to the PCM there is no leak. This is what a 2004 Caravan has. A LDP is used on older vehicles and actually builds pressure in the evap system and monitors time to determine if a leak is present. Newer vehicles use an ESIM, emission system integrity monitor. 
Last edited by teflon; 01/19/12 02:10 PM.
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: JohnRR]
#1160640
01/19/12 04:16 PM
01/19/12 04:16 PM
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Joined: Jun 2008
Posts: 1,822
Colorado
denfireguy
top fuel
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top fuel
Joined: Jun 2008
Posts: 1,822
Colorado
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Quote:
perfect timing on this topic , I have an 04 grand cherokee , got a P0455 code for gross leak. took it in they smoke tested it and found a decayed hose in the back at the evap can ??? fixed , cleared all is good , till yesterday it came back ???
Should I replace he gas cap since what I found online pointed to that as being the cause of this ?
If you took it to Autozone or OReilly, they would have first sold you a gas cap. The dealer did you a favor to actually trouble shoot the problem. I discovered this the hard way with my Durango. Yeah, I bought two gas caps (dummy me) and then dug into the FSM that directed me to the bad hose under the car. Oh, and the emmission check place told me I needed a new gas cap too after they tested it. The hose repair fixed that too.
Craig
2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: denfireguy]
#1160641
01/19/12 04:37 PM
01/19/12 04:37 PM
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Joined: Jan 2003
Posts: 74,992
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,992
U.S.S.A.
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Quote:
Quote:
perfect timing on this topic , I have an 04 grand cherokee , got a P0455 code for gross leak. took it in they smoke tested it and found a decayed hose in the back at the evap can ??? fixed , cleared all is good , till yesterday it came back ???
Should I replace he gas cap since what I found online pointed to that as being the cause of this ?
If you took it to Autozone or OReilly, they would have first sold you a gas cap. The dealer did you a favor to actually trouble shoot the problem. I discovered this the hard way with my Durango. Yeah, I bought two gas caps (dummy me) and then dug into the FSM that directed me to the bad hose under the car. Oh, and the emmission check place told me I needed a new gas cap too after they tested it. The hose repair fixed that too.
Craig
That's all well and good , but it's BACK .
The original repair was under the used car warranty and that ran out right after I had it supposedly fixed , it took 2.5 hours last time. I'm not going to pay 95/hour to sit around and wait for them to TRY something else ...
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: JohnRR]
#1160642
01/19/12 05:10 PM
01/19/12 05:10 PM
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Joined: Oct 2005
Posts: 1,646
Ringtown, Pa.
Dartsport540
top fuel
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top fuel
Joined: Oct 2005
Posts: 1,646
Ringtown, Pa.
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I have had at least 5 customers, Grand Cherokees with that code , for evap leak. There are 2 hoses or 3 hoses going from the gas tank to the evap canister, located behind the drivers rear wheel. 2 of the hoses dry rot and crack. If you can get up in there with a small mirror you can see the hoses being cracked where they go over the barb on the lines. Just replace both hose, not to easy to get at.
1st vehicle that I did, I only replaced the cracked line that I 1st saw . It came back a week later with the same code. I did a little better searching with a small, retactable mirror. Then I saw small cracks in the other hose. Now I just replace both hoses everytime, that I find 1 cracked.
548 cu. in., Bill Mitchell Aluminum Block, CRT 727 auto trans, Alston Chassis. 8.981et at 149.46 mph. 1.204et - 60 foot, So Far....
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: JohnRR]
#1160644
01/19/12 05:26 PM
01/19/12 05:26 PM
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Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
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Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
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Quote:
Quote:
Quote:
perfect timing on this topic , I have an 04 grand cherokee , got a P0455 code for gross leak. took it in they smoke tested it and found a decayed hose in the back at the evap can ??? fixed , cleared all is good , till yesterday it came back ???
Should I replace he gas cap since what I found online pointed to that as being the cause of this ?
If you took it to Autozone or OReilly, they would have first sold you a gas cap. The dealer did you a favor to actually trouble shoot the problem. I discovered this the hard way with my Durango. Yeah, I bought two gas caps (dummy me) and then dug into the FSM that directed me to the bad hose under the car. Oh, and the emmission check place told me I needed a new gas cap too after they tested it. The hose repair fixed that too.
Craig
That's all well and good , but it's BACK .
The original repair was under the used car warranty and that ran out right after I had it supposedly fixed , it took 2.5 hours last time. I'm not going to pay 95/hour to sit around and wait for them to TRY something else ...
HAVE you checked/replaced your gas cap? the gascap is such a common cause, that on the 04 Durango I had, it would actually flash "gascap" or "check gascap" (I cant remember exactly now) on the Odometer, telling to to check it and make sure it's snug/tight. after so many re-starts with the same "code" it would then trigger the check engine light, because it ASSUMED that you checked the gascap and fixed it, meaning that there's another leak somewhere else.
frustrating thing about the gascap is that any time you open it to fill the tank, you might not get a good seal when you put it back on.
if it's NOT the gascap, I'd take it back and complain, sure it's out of your used car warranty now, but if they just fixed it, then you should be in the "your repair didn't work" grace period.
afterall, it might be a different hose, or maybe the technitian who did the repair botched it up and it's leaking at the same hose?
**Photobucket sucks**
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Re: Chrysler guys Explain Difference btwn leak detection pump
[Re: Dartsport540]
#1160645
01/19/12 06:02 PM
01/19/12 06:02 PM
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Joined: Jan 2003
Posts: 74,992
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,992
U.S.S.A.
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Quote:
I have had at least 5 customers, Grand Cherokees with that code , for evap leak. There are 2 hoses or 3 hoses going from the gas tank to the evap canister, located behind the drivers rear wheel. 2 of the hoses dry rot and crack. If you can get up in there with a small mirror you can see the hoses being cracked where they go over the barb on the lines. Just replace both hose, not to easy to get at.
1st vehicle that I did, I only replaced the cracked line that I 1st saw . It came back a week later with the same code. I did a little better searching with a small, retactable mirror. Then I saw small cracks in the other hose. Now I just replace both hoses everytime, that I find 1 cracked.
Thanks , I'll crawl under it if I can't get them to fix it when I go in for an oil change .
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