|Topic Review (Newest First)|
|10-17-2018 09:53 AM|
|10-17-2018 03:45 AM|
|10-17-2018 02:56 AM|
Originally Posted by JumpDrive View Post
|10-14-2018 01:34 PM|
Also, I know how the sensors and gauge works. I don't/didn't care about the sensor, I was wondering if you had verified if the engine was indeed running hot via another source separate from sensor. If the source voltage, or bad ground is present than readings can be wrong.
Also, Fan operations for 1g are approx:
Low speed fan on 210* F Off 199*F
High speed fan on 230*F Off 219*F
So 220* tech is still within Chrysler defined operating parameters to an extent. (Assuming you ment 220*F not C.) I would still feel 220 is high but that is a personal opinion. Not Chrysler defined.
|10-12-2018 01:40 PM|
|10-12-2018 01:37 PM|
|Ronbo||See post #4! I told ya!|
|10-12-2018 12:09 PM|
I think we have success.
Driving today without transducer connected did not manifest any symptoms. Transmission shifts fine, radiator fans were working throughout drive.
I'm guessing the transducer is shorting out inside at a certain temperature.
|10-11-2018 07:47 PM|
I think I am on to something now.
I've been probing away with the DVOM and I get a 5V reference at the A/C transducer, but that 5V reference shorts out very easily. Moving the connector slightly drops it to 0V. It shares that 5V reference with the MAP and TPS. It also shares a ground connection with the air temperature sensor, coolant temperature sensor and crank position sensor.
My A/C transducer connector also looks different from the one in the wiring diagram. Mine has 4 round terminals with 3 wires. I put my DVOM leads on to the TPS to monitor it's 5V signal and messed with the A/C transducer to see if it screws with the signal but it did not seem to.
Question is now, could this explain my symptoms if the issue manifests only when engine is warm regardless of A/C on or off? Could the 5V signal shorting out screw with the grounds on that circuit listed above?
I'll know more tomorrow when I drive it around without the transducer plugged in.
|10-09-2018 01:12 PM|
Did it again today... this is honestly the weirdest thing I've ever experienced in a car. You can damn near time it to your watch when it will happen if you drive the same route. Within a mile every time.
Today I had the heat on the whole time. Driving to my destination was fine, temp didn't get higher than 1/3 and tranny shifted great, quick and firm, but smooth shifts. Coming back is when it happens and sure enough. Only this time while sitting at a light, instead of the transmission trying to go in gear, my brake pedal sinks about an inch, the idle changes a bit then everything is normal. Transmission shifts noticeably different after this point as well as the cooling fans being off.
Weirdest fucking thing I've ever seen by far. Just hope it really is the PCM and my entire car isn't falling apart all at once. So when the PCM gets here I'll update more.
|10-08-2018 03:00 PM|
Originally Posted by JumpDrive View Post
The A/C pressure transducer could very well be faulty. If so, the compressor would turn off and fans would turn off... IF my engine temp was below the threshold for the PCM to keep them on. When engine heats up, PCM should ground the fans. But it doesn't... until I restart the vehicle then fans stay on until engine reaches normal temperature. I don't believe transducer is faulty either as a/c performs perfectly. The PCM only receives signals from those two sensors, which are working fine, to run the cooling fans, thus PCM is suspect.
The TCM relies on data from the PCM also. A faulty PCM can definitely alter shifting of the transmission based on that data if it is bad. Which only happens during this period of odd behavior. So unless the TCM can control the cooling fans (can't) then the PCM is still the common denominator. Won't know for sure until I get one... don't know why these shops aren't calling me back.
|10-08-2018 02:08 PM|
Of course the Transmission act different once warm. Fluid viscosity changes. The TCM will change shifting with fluid temp. If you unhooked battery then you reset the adaptive learning for the transmission. Drive it normally for 100 or so miles as it reads into your driving style.
I did not ask about rather the gauge works. I asked have you verified the overheating issue? Also, a/c transducer can cause several fan issues although most the time it cuts them on. or keeps a/c from turning on. I suggest re looking at it cause if it fails the system will turn fans off ad a/c system off. The factory sensor is no longer easily found so I always grabb a few junkyard ones. Or you have to re wire a new connector for the replacement.
PCM does not control shifting. TCM does. TCM does talk to PCM but ultimately TCM decided shifting not PCM.
|10-08-2018 01:57 PM|
The engine temp and sensor are good.
I disconnected the battery for a few hours yesterday and I'll drive it tomorrow to see how it runs.
The tranny issue is what convinced me of the PCM. Before the cooling fan issue manifests itself, the car shifts perfect with no issues. Once the car has warmed up and has been driving awhile, and usually after turning it off and starting again, it's as if the PCM gets 'confused' for some reason and cuts off the cooling fans. At the same time, the shifting is noticeably different. Around 5 seconds or so after stopping, sometimes the transmission feels like it wants to go into gear, only does it once until I go and stop again.
But those are the only symptoms of the issue. All of the gauges look fine. The coolant gauge behaves normally. A/C works just fine until the fans cut off. Refrigerant pressure is good. No CEL or codes.
I've contacted a few shops from car-parts and haven't gotten a quote yet for a PCM.
I also thought about just eating the diagnostic fee at the dealer since they have the DRB III scanner they could probably tell me immediately what is wrong. But their fee is 3x the price of a used bone yard PCM, figure I'll try it first.
|10-08-2018 02:17 AM|
Also, that surge forward may be it shifting into 1st. What other changes did you see?
|10-05-2018 12:23 PM|
Today I drove without touching the a/c. It was fine through highway and some lights until I turned the car off. Turned it back on and didn't drive one block before I clearly noticed a change. Even my transmission was shifting weird a couple of times. At a stop, if my car was in gear, it would jolt forward slightly shortly after stopping.
Going to order a PCM and hope it fixes it. Otherwise it could be a ground issue.
|10-04-2018 07:39 PM|
Why would the PCM turn off the fans is a more important question. The fans don't turn off and off by themselves.
If a PCM is cheap enough that would be my next route. After that you're looking at a possible wiring/connector problem. Again possible temperature related to break a connection somewhere.
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