Hello everyone, just had the dreaded P1648 code. Car was running pretty good until I parked it Friday evening, Saturday morning started the car it was shaking like crazy, left it to idle for about 5 minutes it returned close to normal, took the car down the freeway for a blast no problem at all drove well was responsive as usual.
Sunday morning, started the car it was shaking a lot harsher. It barley wouldn't drive, so I parked the car.
Scanned it today and had the P1648 code. I need help with sorting it, anyone dealt with this before please help.
Regards y'all.
Then I'd say you have a glowplug issue bud... The code relates to that in a CRD and the symptoms are of a bad glowplug not heating the fuel to allow easier combustion. Once she's warm you are fine... I'd take it in and see if they can narrow down which one is dead.
Yep... Looks like right on top of the heads. Not a bad swap... Think there is a module as well that runs all of them, but pretty sure if it puked she would pretty much turn or ten mins to start.
Correct! This is what P1648 refers to. There are separate DTCs for each of the 6 glowplugs, but these may not appear if the module is kaput. Module failures are not uncommon and replacements are now much cheaper than they used to be. Once the module has been replaced, a further scan will reveal any faulty glowplugs. Glowplug failures also seem to crop up frequently. Glowplugs are reasonably accessible, but the top cap can be difficult to remove without special pliers.
Thanks guys I appreciate your guides and suggestions. Prior to the fault the car always start without any fuss, I'll start with the glow plug module and see what's up.
An update. I've had 2 surgeries 3 days after the post and another scheduled in a week time. I've been indoors ever since. Started moving around last week.
I changed the glow plug module today, it started with less hassle but runs rough for the first 5 minutes. Scanned it and glow plug 4,5&6 are coming up. Would attempt to change those in the next 2 weeks and update.
most cars and trucks now a days have an electric plug in to keep your engine warm over nite etc.may be you
could leave it plugged at nite until you resolve the issue.lotsa luck. ray
I replaced glow plugs 4, 5 & 6 the problem is still persisting. The removed glow plugs are damp when I removed them. I'm getting an extra code for glow plug number 3. I'm thinking maybe the module is not right though it's not showing any code or a relay issue, any idea guys? I need to get this car running right before school starts on Wednesday.
I have just noticed that the glowplug positions shown in an earlier post are incorrect. These cylinder numbers actually refer to the 3.5 petrol engine.
What the heck... That diagram is from Chrysler! Lol. Nice... Also the image is clearly the diesel as it has a turbo and glow plugs... Not much use for glow plugs in a n/a petrol engine. That's 2 diagrams I've pulled from Chrysler that are incorrect then!
No apologies needed! Chrysler documentation is well known for errors. I think the correct diagram for the CRD is somewhere in the Service Manual, but I can't remember where. I must have got it from somewhere.
The Service Manual contains two different versions of CRD cylinders layout and I suspected that one version might have been erroneously adapted from the 3.5 petrol layout. A separate check on the 3.5 engine confirmed this.
Two of your replacement plugs are accidentally where they are needed (in CRD cyls 5, 6). All you need to do is take the plug from CRD cyl 3 and put in CRD cyl 4. The original CRD cyl 3 plug can be re-instated. BTW, have you tested the "failed" plugs for continuity? A good plug will be almost short-circuit and a bad one will have a fairly high resistance, possibly open-circuit.
The only reason I can think of for over-fuelling is if you managed to interrupt a DPF regen just before removing the plugs.
I've just realised that Cyl 3 was throwing a DTC, so best leave the new plug in there and get a new one for Cyl 4.
Only one of the glow plug removed had a resistance of around 38.5.
I did a resistance test on 3, 2 & 1 glow plugs 3 and 1 were 01.2 & 01.8
Replaced those the vehicle wouldn't even start at all.
I plugged a spare glow plug to cylinder on the two middle glow plug 3, 4 and 2 (as in the 3.5 diagram referring to that for now) only glow plug 2 glowed.
I carried out a resistance test on the wiring from the glow plug module connector and there were OK.
I'm. Thinking maybe the glow plug module is pants?
A good glowplug will only have a resistance of a fraction of an ohm ( 0.5 ohm @ 4.4V = 8.8A, which is about the level of current needed). In order to measure such low resistances, the test meter probes need to make very good contact with the plug terminal and body and I suspect that your slightly higher readings could be partially due to probe contact resistance. The reading of 38.5 ohm would definitely indicate a faulty plug.
Your original post identified the glowplug module DTC and this does appear to be the main issue.
Sorry, can't help with fuse 5 at the moment, without consulting the service manual. Why do you need to know?
Actually I changed module with a used one, the guy that sold it to me sound like a pretty honest guy. Not sure when I'll get it sorted now, going for another surgery tmr unfortunately.
Would any om642 glow plug module work in our 300c CRD?
The original DTC did not reappear since I replaced the module. Since I've changed the glow plug it doesn't start start at all. It cranks until the battery is weak.
In the current mild weather conditions, faulty glowplugs shouldn't prevent the engine starting. You may have another problem, possibly crankshaft sensor failure. The attached TSB relates to this issue on certain 2006-8 models. Also, crankshaft sensor failure does not set a DTC. If the sensor is OK, then you should see an rpm reading on your rev counter whilst cranking.
Thanks for that. I've already replaced the crankshaft position sensor a little over a year ago.
I'm going to get another glow plug module and see what's up.
I've virtually ran out of ideas with my car.
Replaced glow plug module again still won't start. Scanned and the coolant temperature sensor DTC came up. Replaced that it started but it's still shaking from cold.
I'm suspecting bad injector or faulty diesel. Would add some few gallons of diesel with treatment and see how it goes. Failing that would be the end of my slobbering love affair with it.
Sorry to hear that you are no nearer to a solution. I'm not convinced that glowplugs and/or module are the main culprit, as in the current weather, even with faulty glowplugs, the engine should start and eventually run smoothly as it warms up. It is also strange that you have now had a coolant sensor DTC for the first time and I would think a coolant sensor fault would be no worse than a glowplug fault; ie, it should not prevent the engine starting. Did you ever check the wiring harnesses for chaffing on both sides of the engine and in particular, the one that runs close to the A/C pipe? There have been several reports of chaffed harnesses causing problems when signal wires are shorted to ground.
You also mentioned the possibility of a fuel problem. Have you any reason to believe that your diesel might be of poor quality? When was your fuel filter last changed? The filter also acts as a water trap, but there is no drain cock, so the filter must be changed at the prescribed intervals (I think 25K miles).
If you had injector problems then you probably would have seen a relevant DTC.
Yeah I'm really scratching my head in this case. Definitely not the glow plug/module issue it's either the DTC for those were already available before the problem or the problem triggered those. I agree It should be starting without issue in this weather.
Because I had to disconnect the coolant sensor before changing the glow plug a few times maybe it affected the connector.
Yeah I've checked the wiring harness, it's well insulated, no chaffing or anything.
This issue started shortly after I filled the car up with shell nitro diesel. I last changed my filter at 97k miles it is at 103k now.
I'm thinking maybe an injector is leaking diesel back into the engine, faulty diesel or maybe the ECU not sending appropriate signals to the glow plug module.
I've filled it up with BP ultimate diesel and added miller diesel treatment. It ever run so sweet once it warmed up. Would check it tmr morning and see if that helped.
This morning I started the car to my sweet surprise it's running just fine.
So is it the case of bad diesel or the diesel treatment making the diesel easily combustible?
Will see how it turns out, hoping it's an actual solution and not a fluke.
As you've been using top quality fuels (as I do) and your filter is fairly new, it doesn't look like a fuel problem. Although you've added "treatment" I'm not sure its effect would be instantaneous, but I could be wrong.
Car still starting OK, so I suspect it's probably a bad batch of diesel from shell. Took it for MOT today, it failed on front lower suspension and headlight washer. Would sort those at as soon as I can.
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