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#1
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300M Check Engine Light
Over the years the Check Engine Light on our '02 300M has activated, and
the "key dance" has indicated that the fault code is P0440 or P0441. I've deactivated the light by disconnecting the battery or pulling the appropriate fuses, and the CEL has usually stayed dark for a long time. It's never re-illuminated in time for a regular service so they can check it out. Not long ago the CEL illuminated again, and I hadn't got around to either doing the key dance or pulling the fuses. But then when I drove the car on Friday I noticed that the CEL was not on. I mentioned it to my wife, who said, "Oh yes. All the instrument panel lights flashed off and on, and then when they came on again the CEL was off." What could have happened here? Spontaneous reboot of the computer? Perce |
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#2
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300M Check Engine Light
Percival P. Cassidy wrote:
> Over the years the Check Engine Light on our '02 300M has activated, and > the "key dance" has indicated that the fault code is P0440 or P0441. > I've deactivated the light by disconnecting the battery or pulling the > appropriate fuses, and the CEL has usually stayed dark for a long time. > It's never re-illuminated in time for a regular service so they can > check it out. > > Not long ago the CEL illuminated again, and I hadn't got around to > either doing the key dance or pulling the fuses. But then when I drove > the car on Friday I noticed that the CEL was not on. I mentioned it to > my wife, who said, "Oh yes. All the instrument panel lights flashed off > and on, and then when they came on again the CEL was off." > > What could have happened here? Spontaneous reboot of the computer? > > Perce Perce - My best guess is that something sucked the system voltage below the PCM reset level momentarily. One likely cause is that the battery has an intermittent internal short (that's often how they act towards end of life). Other possibilities are a momentary main bus short (to ground) elsewhere, or a poor (intermittent) connection either on the power system or ground. For poor connections, check: (1) Pos. and neg. right at battery (tends to be a lot of corrosion unless checked and cleaned periodically on these cars due to hidden battery location), (2) Positive jump post connections (*not* the battery post - the place where you would jump the car off - nect to the air cleaner) - *all* power (with the exception of the connection between the battery and alternator) go thru that junction and rely on good clamping, and (3) Negative jump post - located on the passenger side strut tower - that is the main vehicle ground point. How old is the battery? On the two codes you're getting - you do know that one of the more frequent causes of that are gas cap not being screwed on tight enough to seal, or defective gas cap. The fact that those codes are few and far between for you give hope to that. If that's not it, there is a valve and a couple of hoses that are the other common causes of that in the 2nd gen. LH cars. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |
#3
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300M Check Engine Light
On 04/05/10 05:21 pm, Bill Putney wrote:
>> Over the years the Check Engine Light on our '02 300M has activated, >> and the "key dance" has indicated that the fault code is P0440 or >> P0441. I've deactivated the light by disconnecting the battery or >> pulling the appropriate fuses, and the CEL has usually stayed dark for >> a long time. It's never re-illuminated in time for a regular service >> so they can check it out. >> >> Not long ago the CEL illuminated again, and I hadn't got around to >> either doing the key dance or pulling the fuses. But then when I drove >> the car on Friday I noticed that the CEL was not on. I mentioned it to >> my wife, who said, "Oh yes. All the instrument panel lights flashed >> off and on, and then when they came on again the CEL was off." >> >> What could have happened here? Spontaneous reboot of the computer? > My best guess is that something sucked the system voltage below the PCM > reset level momentarily. One likely cause is that the battery has an > intermittent internal short (that's often how they act towards end of > life). Other possibilities are a momentary main bus short (to ground) > elsewhere, or a poor (intermittent) connection either on the power > system or ground. > > For poor connections, check: (1) Pos. and neg. right at battery (tends > to be a lot of corrosion unless checked and cleaned periodically on > these cars due to hidden battery location), (2) Positive jump post > connections (*not* the battery post - the place where you would jump the > car off - nect to the air cleaner) - *all* power (with the exception of > the connection between the battery and alternator) go thru that junction > and rely on good clamping, and (3) Negative jump post - located on the > passenger side strut tower - that is the main vehicle ground point. > > How old is the battery? New battery last November. And removing power by disconnecting the battery or pulling the fuses for just a few seconds doesn't usually reset the computer, does it? I've read that one should wait 10 minutes or so. > On the two codes you're getting - you do know that one of the more > frequent causes of that are gas cap not being screwed on tight enough to > seal, or defective gas cap. The fact that those codes are few and far > between for you give hope to that. If that's not it, there is a valve > and a couple of hoses that are the other common causes of that in the > 2nd gen. LH cars. I'd read that, and I replaced the gas cap. CEL still illuminates from time to time. It did switch off on its own at least once before -- without anyone noticing flashing instrument panel lights. Perce |
#4
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300M Check Engine Light
Percival P. Cassidy wrote:
> New battery last November. > > And removing power by disconnecting the battery or pulling the fuses for > just a few seconds doesn't usually reset the computer, does it? I've > read that one should wait 10 minutes or so. You are correct - *however*, that is without shorting the bus to ground - IOW, capacitors in the front ends of the various modules have to discharge by leakage currents for the bus voltage to drop to the PCM's reset levels - that's the reason for the 10 to 15 minute wait period. Experts know that *IF* you were to disconnect the battery and short the bus to ground (it would be better to use a resistor to limit current), the reset of the PCM occurs right away (only as long as it takes to discharge the total capacitance hanging on the bus) - which would also happen if the battery were to internally short, bringing the power bus momentarily to ground. >> On the two codes you're getting - you do know that one of the more >> frequent causes of that are gas cap not being screwed on tight enough to >> seal, or defective gas cap. The fact that those codes are few and far >> between for you give hope to that. If that's not it, there is a valve >> and a couple of hoses that are the other common causes of that in the >> 2nd gen. LH cars. > > I'd read that, and I replaced the gas cap. CEL still illuminates from > time to time. Then you likely have a problem in that valve or a break/crack in one of the purge system hoses (IIRC, one of the hoses is just under the air filter box) - details are available on some of the LH car forums (www.dodgeintrepid.net and www.lhforums.net). I've never had this problem on either of my Concordes, so I tend not to remember the exact details. > It did switch off on its own at least once before -- without anyone > noticing flashing instrument panel lights. Yes - some of these codes/CEL's automatically disappear after some fixed number (50 I think?) warm-up/cool-down cycles without the fault recurring. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |
#5
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300M Check Engine Light
On 04/05/10 05:21 pm, Bill Putney wrote:
>> Over the years the Check Engine Light on our '02 300M has activated, >> and the "key dance" has indicated that the fault code is P0440 or >> P0441. I've deactivated the light by disconnecting the battery or >> pulling the appropriate fuses, and the CEL has usually stayed dark for >> a long time. It's never re-illuminated in time for a regular service >> so they can check it out. >> >> Not long ago the CEL illuminated again, and I hadn't got around to >> either doing the key dance or pulling the fuses. But then when I drove >> the car on Friday I noticed that the CEL was not on. I mentioned it to >> my wife, who said, "Oh yes. All the instrument panel lights flashed >> off and on, and then when they came on again the CEL was off." >> >> What could have happened here? Spontaneous reboot of the computer? > My best guess is that something sucked the system voltage below the PCM > reset level momentarily. One likely cause is that the battery has an > intermittent internal short (that's often how they act towards end of > life). Other possibilities are a momentary main bus short (to ground) > elsewhere, or a poor (intermittent) connection either on the power > system or ground. > > For poor connections, check: (1) Pos. and neg. right at battery (tends > to be a lot of corrosion unless checked and cleaned periodically on > these cars due to hidden battery location), (2) Positive jump post > connections (*not* the battery post - the place where you would jump the > car off - nect to the air cleaner) - *all* power (with the exception of > the connection between the battery and alternator) go thru that junction > and rely on good clamping, and (3) Negative jump post - located on the > passenger side strut tower - that is the main vehicle ground point. The CEL came on again, and I had pulled the fuses a few days ago. The CEL was still off. Earlier this evening -- still daylight, so the lights were not on -- I had to wait for a train, so I switched off the motor. After a minute or so I heard a rapid clicking noise from the left-hand end of the dash, and when I turned the key the instrument panel lights were dimmer than they had been, but I was able to readjust them back to normal brightness. I think I must have a bad (intermittent) relay -- or a bad connection to one of the relays. Finding which one could be a problem. Perce |
#6
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300M Check Engine Light
Percival P. Cassidy wrote:
> The CEL came on again, and I had pulled the fuses a few days ago. The > CEL was still off. > > Earlier this evening -- still daylight, so the lights were not on -- I > had to wait for a train, so I switched off the motor. After a minute or > so I heard a rapid clicking noise from the left-hand end of the dash, > and when I turned the key the instrument panel lights were dimmer than > they had been, but I was able to readjust them back to normal brightness. > > I think I must have a bad (intermittent) relay -- or a bad connection to > one of the relays. Finding which one could be a problem. > > Perce What year is your M? You need an FSM so you can study the schematics to figure which relays, etc., relate to your symptoms. I can email you a link to access an FSM for some years (and certain years are so similar that you're probably covered by an adjacent year). -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |
#7
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300M Check Engine Light
On 04/14/10 05:56 am, Bill Putney wrote:
> Percival P. Cassidy wrote: > >> The CEL came on again, and I had pulled the fuses a few days ago. The >> CEL was still off. >> >> Earlier this evening -- still daylight, so the lights were not on -- I >> had to wait for a train, so I switched off the motor. After a minute >> or so I heard a rapid clicking noise from the left-hand end of the >> dash, and when I turned the key the instrument panel lights were >> dimmer than they had been, but I was able to readjust them back to >> normal brightness. >> >> I think I must have a bad (intermittent) relay -- or a bad connection >> to one of the relays. Finding which one could be a problem. > What year is your M? You need an FSM so you can study the schematics to > figure which relays, etc., relate to your symptoms. I can email you a > link to access an FSM for some years (and certain years are so similar > that you're probably covered by an adjacent year). It's an '02, and I do have the service manual -- which I have not yet consulted. But there is a layout guide on the inside of the cover on the end of the dash, but no relays seem to have anything to do with the instrument panel -- fuses, yes, but no relays. I pulled and reinstalled the fuses, but I don't know whether that will accomplish anything. Perce |
#8
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300M Check Engine Light
Hi!
> Earlier this evening -- still daylight, so the lights were not on -- I > had to wait for a train, so I switched off the motor. After a minute or > so I heard a rapid clicking noise from the left-hand end of the dash, > and when I turned the key the instrument panel lights were dimmer than > they had been, but I was able to readjust them back to normal brightness. I hear that and immediately think "bad ground". Or a flakey ground connection somewhere. Bad or flakey grounds will cause all manner of screwy behavior. It's worth a look... William |
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