2.7L P1391 & P1684 after car buckin and nearly stalling on freeway then back to normal!

476 Views 38 Replies 4 Participants Last post by JordanS, 20 d ago

99intrepy

Discussion Starter · 27 d ago

Ok I got my 1999 Intrepid SE 2.7 all done and was driving around the city all day. Today has been the hottest day of the year so far and I was running the air conditioning most of the day. It was driving good, all of a sudden I jump on the freeway 100km per hour and it starts buckin and kickin like a buckin bronco then the check engine light is thrown on and nearly stalls but somehow she regains her composure and goes back to driving normally and I make it to my destination and drive the rest of the day with no issues. The codes I found were P1391 and P1684. Do you think it is a bad crankshaft position sensor? Or could it be something else? I don't believe I have ever changed the crank position sensor or cam sensor on this car.

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cdmccul

· #2 · 27 d ago

Crank and cam sensors don't like the heat... When the seasons change, and get warm, you'll see a seal sensor fail. You could locally cool down a single sensor (with water) and see if it comes out of it. Then if not, try the next sensor.

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99intrepy

Discussion Starter · #3 · 27 d ago

cdmccul said:
Crank and cam sensors don't like the heat... When the seasons change, and get warm, you'll see a seal sensor fail. You could locally cool down a single sensor (with water) and see if it comes out of it. Then if not, try the next sensor.

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Yes it definitely seemed like the crank sensor cut out then returned. Also the code for crank sensor seems to confirm that. I will check the wiring too but most likely the crank sensor should be changed. I can't see a true Mopar sensor for sale anymore but looks like the favorite is the Standard brand. Which one you like?

cdmccul

· #4 · 26 d ago

I'm the black sheep around here... Buy parts and install. They are designed to work. If they weren't, they wouldn't be sold. Chinese sourced eBay/aliexpress fodder not withstanding.

Yes, cheap parts can be cheap... But it might at a NAPA, AutoZone, Parts America, Checker, Canadian Tire, Car Quest, or the Irish Mafia, try should be at least some what trusted, right?

I'm of the opinion... Having worked in aftermarket parts... Not every time, but more often than not, the "premium" version of a part costs more, because the warranty is better. Not because the part is better. (Not talking about OEM, just aftermarket)

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99intrepy

Discussion Starter · #5 · 26 d ago

cdmccul said:
I'm the black sheep around here... Buy parts and install. They are designed to work. If they weren't, they wouldn't be sold. Chinese sourced eBay/aliexpress fodder not withstanding.

Yes, cheap parts can be cheap... But it might at a NAPA, AutoZone, Parts America, Checker, Canadian Tire, Car Quest, or the Irish Mafia, try should be at least some what trusted, right?

I'm of the opinion... Having worked in aftermarket parts... Not every time, but more often than not, the "premium" version of a part costs more, because the warranty is better. Not because the part is better. (Not talking about OEM, just aftermarket)

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Yeah you would think so. However in my experience in my life whenever it comes to anything to do with ignition, I've been burned by cheap parts enough that I don't consider them. They seem to never be designed to manufacturer spec which causes issues.

On another note, the other code I had was for the TCM losing power. Do you think this can also be caused by the event of the crank signal loss? I had no codes for a long time and these 2 came together today.

peva

· #6 · 26 d ago (Edited)

The correct code informations (from the Chrysler FSM):

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P1684 can be triggered simply by a slightly low system voltage, perhaps from a temporary dip from load of starting or other higher current loads due to slightly high resistance of an older, not fully charged, or failing battery or a loose or corroded cable connection. The cause of the P1684 code would not be causing the P1391 code or its related symptoms. My guess is that you've had the P1684 code for a while but just didn't know it. Pretty common even when everything's working fine. A lot of people just ignore it. But if your battery is a few years old, it may be due. Might also visually inspect and disassemble and clean all main +12 volts and ground cables (again - loose, covered in battery acid residue, or corroded).

The P1391 is not about TCM voltage per-se. It is about system (battery) voltage as sensed by the PCM dropping below the threshold in the PCM firmware.

Troubleshoot and correct the causes of those 2 codes separately.

On sensor brands, the comon sense logic about engine sensors doesn't apply to some of the engine sensors for Chryslers. For example, it is known in the Chrysler community that Bosch O2 sensors are not compatible with the Chrysler signal sensing electronics (the design flaw shifts the dc voltage level of the sensor output signal just enough that the signal may be detected by the PCM sometimes, but not at some normal operating temperatures). You'd think a reputable company would figure that out over the many years that the problem has existed and been known about, but for some reason Bosch still sells the incompatible O2 sensors. Doesn't make sense but it is a proven fact. While the aftermarket cam and crank position sensors aren't known to have an actual design incompatibility, enough people here have found that the general hit and miss quality and reliability of aftermarket sensors have caused a lot of headaches. One exception is NTK sensors (they are the factory sensors). Rock Auto has the NTKs. Amazon might also.

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99intrepy

Discussion Starter · #7 · 25 d ago

Guys I got a crank sensor from the junkyard today and good timing as it completely failed and car wouldn't start while there. I installed it on my back and it fired right up. Cleared codes I drove around on a few trips today. Driving fine. Then this evening as I was parking the car it was weird, I shut the car off and took out the key. And the oil light stayed on dimly lit and the odometer was showing which I think is normal then when it went off so did the oil light. Then I turned the key to start, no start! No starter engagement. But turning the key makes the climate motors all cycle and a code popped up without even doing the key dance. P1684. It is super weird. What is happening? I'm at home at least but the fun never ends with thi

99intrepy

Discussion Starter · #8 · 25 d ago

Here is a video of what is happening. I don't get it.

99intrepy

Discussion Starter · #9 · 25 d ago

Well guys looks like it must be the ignition switch. I jumped the starter relay and it started.

cdmccul

· #10 · 25 d ago

Loose battery cable, corroded at one of the cable ends, etc etc. Ever serviced the jump post? You might try wiggling, bending, gently twisting, all the battery cables, then trying the key again.

But honestly sounds like another issue.

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99intrepy

Discussion Starter · #11 · 25 d ago

cdmccul said:
Loose battery cable, corroded at one of the cable ends, etc etc. Ever serviced the jump post? You might try wiggling, bending, gently twisting, all the battery cables, then trying the key again.

But honestly sounds like another issue.

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Yeah battery is good. It appears it is the ignition switch. I read another guy from 2010 on this forum who had a similar problem. Oil light dim. I jumped the starter relay and it started. then I go for a drive and the switch works again like nothing happened. That is so annoying. Obviously I need to change this switch before she leaves me stranded.

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99intrepy

Discussion Starter · #12 · 24 d ago

Oh how the fun never ends. Turns out the wiring harness and or connector to the ignition switch is bad. I wiggle the harness and was working then not for the signal lights and airbag. It starts but I got no signal lights now and that connection is not even working with wiggling anymore. I guess now I gotta get to the junkyard and carefully cut a whole ignition switch harness and hope it works. I was removing an old remote starter which was spliced in about 25 years ago but I believe the plug to the switch seemed the culprit. The pins look ok. I don't know anymore. Just frustrated.

99intrepy

Discussion Starter · #13 · 24 d ago

After struggling I believe it might be a pin fittament issue in the harness to the ignition switch. I will take the pins out tomorrow and see if I can tighten up the connection. Clean too. Wiggling had it fixed especially pushing inward on the wire. I'll update you. Unfortunately no new pigtail connector is available to buy so it is junkyard or fix. Seems that connector is the only answer.

peva

· #14 · 24 d ago

Sounds like you found the problem, which is half the battle. Hopefully you can find a loose or corroded terminal that you can reshape or clean.

I don't recall how big that harness is and how involved it would be to replace. If too involved, consider snipping a junk yard cable and splicing - but be sure to make reliable splice connections so you're not creating a new headache. Soldering and shrink tubing is the most reliable; crimped connections can be iffy unless you have a decent crimp tool and good technique.

99intrepy

Discussion Starter · #15 · 24 d ago

peva said:
Sounds like you found the problem, which is half the battle. Hopefully you can find a loose or corroded terminal that you can reshape or clean.

I don't recall how big that harness is and how involved it would be to replace. If too involved, consider snipping a junk yard cable and splicing - but be sure to make reliable splice connections so you're not creating a new headache. Soldering and shrink tubing is the most reliable; crimped connections can be iffy unless you have a decent crimp tool and good technique.

Guys I am having a nightmare here. I have tried 2 ignition switches from the junkyard. The first one worked when I wiggled the wire and pushed in. So I thought it was the harness from the remote starter, so I removed that, cut out the affected wires, and put it back together. Then I couldn't even wiggle anymore to get it to work with climate control and power windows etc. The wire that runs those is black / orange stripe. Ok so to diagnose that, I used my voltmeter DC. I get a normal 12 volts from the red wire which I believe is the main coming in. Am I right in that the black with orange stripe should have 12 volts coming out in the run position? Or am I missing something. I get 1.1 volts from that wire. Climate doesn't work, power windows don't work all the things in the picture don't work. Now it won't even start. It does crank. It does fire up the fuel pump from the blue white wire. Is it that I just got bad switches from the junkyard? Is there something I'm missing?

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99intrepy

Discussion Starter · #16 · 24 d ago (Edited)

In other words, getting that 1.1 volts from the wires that should have 12 volts, does that make it the switch that is at fault or could something else cause that? Are these switches that fragile? I opened one to see and it was ruined from trying that. A fork inside looked a little burned but not super bad or anything.

The thing that has me stumped is the original switch which was working before is doing the exact same things as the junkyard switch. Will crank, won't start, same 1.1 volts at the wires that should have 12 volts. That's why I figure the chances of that seem slim. I don't know. I am just at the end of my rope here. Please help if anyone knows what might be wrong.

99intrepy

Discussion Starter · #17 · 23 d ago

Guys do I read correctly on that picture I posted, when in the run position the ignition switch should be 12 volts or battery voltage correct? Does anyone know how the power comes in and out of the switch? Is it the red which is always hot then it connects in the switch internally and pushes the 12 volts to the circuit above? Basically is there any other reason I could not have 12 volts coming out of that black orange wire other than a bad switch?

99intrepy

Discussion Starter · #18 · 23 d ago

One more thing pink and black wire which I read is supposed to be battery positive 12 volts which is opposite the orange black which drives the accessories, well that has only 1.1 volts on it. Does that mean the switch inside is bad? Or is there some ground that could cause this? I think it is the switch. But how could all the switches I tried do similar things? One thing is the clock spring I sort of made a little boo boo with while trying to get the multifunction switch out. It looks fine but I thought I might have disturbed the housing of it a little bit but I doubt it is it. Because the car worked fine when messing with the harness after that.

cdmccul

· #19 · 23 d ago

Trying to follow you here... You removed the Tee Harness for the remote starter, and plugged the switch directly into the factory wires? Or is that aftermarket harness still involved? It sounds to me like the harness is at fault.

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99intrepy

Discussion Starter · #20 · 23 d ago

cdmccul said:
Trying to follow you here... You removed the Tee Harness for the remote starter, and plugged the switch directly into the factory wires? Or is that aftermarket harness still involved? It sounds to me like the harness is at fault.

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I cut out the old harness thinking it was to blame and got a really nice one from a donor car. I soldered and heat shrinked it. It is solid and I did test the harness for continuity before installing. The way the switch works inside looks like I should have battery power to the thick wires in the run position. But the 2 wires running on the one fork inside the switch are showing only 1.1 volts while the others show 12 volts. Seems no other answer but the switch is bad yes? The switch I took apart did have dirty looking contacts inside. I mean the service manual shows no way to test the switch and I gather that the wires should just have battery voltage on them in the run position. Getting that weird 1.1 volts which is supposed to run the power windows, climate controls, signal lights. But now plugging in that switch I have crank but no start now. Is there anything I'm missing here?

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