2005 PT Cruiser starting problems/Possible bad PCM

chrysler
ptcruiser

#1

I got in my 2005 PT Cruiser and tried to crank it to go to work Monday morning. The motor turned over twice, but then the lights went dim, the engine stopped and then it started turning as if there was a bad battery. I let off the key for a second, and tried it twice more, but the engine turned like it was out of time to no compression sometimes. I got out of the car and smelled an electrical burnt smell. I pulled the engine code and got U110C, which after contacting 3 dealerships was told the PCM/BCM arent’ communicating properly, which could range from a shorted ground to a bad PCM. With the burning smell, I was betting on the PCM since the car has 180,000 miles and has been running rough and not getting good milage lately. I uninstalled the PCM and noticed the VIN on the part and the car did not match, which leads me to believe it has been changed once before. I also noticed a Chrysler sticker under the hood that indicated a PCM reprogram was completed years ago, but after tracking the dealership down to the matching dealer code, was not able to find out any information about a PCM reprogramming. I contacted a company about a used PCM to replace my what I assume is defective PCM and they said since the VIN #'s don’t match, it is possible the PCM and immobilizer was changed, and there is no way to no which VIN number is in the current PCM. I need to get this thing running. What can I do? Since the sticker is under the hood showing a reprogram was completed, is it possible to assume the dealership flashed the PCM with the right VIN? I need to purchase a replacement, but I don’t know what to get since I am unsure of the old PCM. I have found replacement PCM/Immobilizer/key switch w/one key sets on ebay, but I run into the problem of needing more keys and from what I have read, programming a new key takes 2 older keys. Any help/advice would be greatly appreciated. Thanks in advance.


#2

Check all the fuses, and it is possible you may have a fusible link, a wire that acts like a fuse, this may be helpful


#3

I would think that the dealership that replaced and reflashed the PCM put the current Vin from the Cruisers VIN number. If they didn’t then I don’t think the PCM could communicate with the Body control module and the security system.

As far as the Keys go. A new key can be cut from the one key that comes with the new PCM.
You may have to jump through hoops and show them your title and the receipt for the new PCM to prove it is really your car.

Yosemite


#4

Before replacing the PCM I’d be inclined to recharge the battery and do a spark and fuel pressure test. It may be something unrelated to the PCM that is causing it not to start. If the battery got drained during the starting attempts, that could easily explain the PCM/BCM miscommunication problem.


#5

How old is the battery? Are the battery connectoins clean? Have you checked all the fuses? Have you looked and smelled around for the burnt smell? I would do that and what the others suggested before condemning the pcm.


#6

The PCM had a faint smell on it when I took it off, but that was several days later. I don’t smell a burnt smell now. The battery was replaced last year, so it is still new. The battery didn’t get drained during the starting, I only turned the engine over a few times, and did not stay on it. The burnt smell was fairly predominant after I first attempted to start the car.


#7

How did you get from a simple no-start problem to needing a PCM, with no intermediate diagnosis? The fact that the engine sounds like it’s out of time or no compression indicates a mechanical problem. The burning smell could have been your timing belt shredding. You don’t even know how long your U-fault code was present, do you? Did you note how long ago the code was set before you started removing things?

Put everything back together. Try to start the engine while watching your scan data. Check for spark, check fuel pressure, check compression. Let us know what you find.


#8

The code was not there until the problem started. I have tried cranking the car before removing the PCM and it did turn over with compression, it just didn’t seem timed, it didn’t sound right like it was fighting itself.


#9

Here’s what I think happened: Either your battery was low (for whatever reason) or your starter is failing. That would explain the slow cranking. When battery voltage is low or with an internally shorted starter, the starter will draw an enormous amount of current from the battery, more than it is meant to, and more than the wiring is designed to handle. This overcurrent condition will rapidly heat up the wiring and starter. I think this was your “burning smell”

When battery voltage is very low, either due to the battery not being charged or because it can’t keep up with what is being demanded of it from a shorted starter, electrical modules will begin to misbehave and lose communication with each other–this is your “U” code you got.

The first thing I would do is charge the battery fully and have the current draw for the starter checked.


#10

I did look and see the battery cables were very corroded, so i cleaned them. I put everything back together, and now the car turns over, slowly, but you can tell there is compression. I used the odometer trick of turning the key 3 times and got the new code from the computer and it shows p0522, which is the oil sending unit, but the car still will not start. Will this keep the car from starting?


#11

If the car is turning over slowly with a full battery and good connections, it’s likely the starter is bad. It may not be starting because of the excessive voltage drop and the engine not cranking fast enough to fire.


#12

I was just told by my wife she probably ran it out of gas. It is turning over again, but doesnt appear to be getting fuel. I did t have any starting fluid, but used wd-40 a d it acted like it was going to come alive a d then quit. I put gas in it, but dont know if i will have to prime it to get it to start again.


#13

Why would you use WD-40 in place of starting fluid? They are definitely not interchangeable. The WD-40 probably didn’t do any major harm, but depending on how much you used, you may have fouled spark plugs now too to add to your woes. I would pull the plugs and check their condition.


#14

Since you got an oil pressure sending unit code, be sure to check your oil level before any further attempts to start the engine. You may need to look in your owner’s manual or check with a GM dealership shop whether an oil pressure problem causes the computer to prevent the engine from starting. I think some cars are designed that way, to help prevent major engine damage in the event of loss of oil pressure.


#15

Sorry, I have been busy, but I wanted to post the findings of my problem and the solution. It turns out, the batter terminals/connections needed further cleaning. Then, because the car continuously turned without stating, apparently this fowled my plugs. So after pulling them, cleaning them and the terminals/connections, the car started perfectly and has ran correctly since. A simple fix. That’s why I hate these newer computerized cars.


#16

“That’s why I hate these newer computerized cars.”

Okay . . . you said the problem was corroded battery terminals, plus fouled plugs

This has nothing to do with computerized cars

This would even cause an older car with points and and a carb to not start

This is an example of why you need to check the basics first

This story just goes to show that the pcm is usually not the culprit. Only consider it after ALL other possibilities have been eliminated. Many people condemn the pcm when there are still many things that haven’t been tested

:triumph:


#17

Your plugs were not fouled by not starting, they were fouled by spraying WD40 into the intake as Oblivion pointed out.


#18

You might consider making battery terminal maintenance one of those routine weekend chores; say once a year. It only takes a few minutes and can nip a lot of problems in the bud before they even begin.

The same goes for routine checks of fluid leaks, accessory belt condition, tire treadwear irregularities, and so on.

For what it’s worth and while it may often not seem to be the case, many problems often have a root cause that is very simple. It’s very easy to overthink a problem while dwelling on computers, sensors, miles of wiring, and so on.

Modern engine management systems are amazingly reliable considering the temperature extremes, vibrations, fluid vapors and leaks, etc that they’re subjected to.
Far different from the desktop PC with IE error reports and blue screens of death…


#19

2005 PT cruiser pulling my hair out… OBD2 port no communication… took it to a repair shop with a P0335 Crankshaft sensor after the port can’t be read read it on the cluster but now won’t read in cluster do no way to read codes …had crankshaft sensor replace they were trying to fix the OBD2 port now the codes for U0155, U0160, U110C , P0031 low voltage on both P0037 02 sensors
02 sensors were replaced 1 month ago…

. the mechanic said on the PCM the 2 connectors to the left had pins out! Could the connectors be causing this? Thank you for broadcast… S.O.S. Do you have information on what each connector contol plugged into the PCM for 2005 PT Cruiser? All the mechanic here are throwing their hands up… I was told the ground on the PCM to the 02 sensor may be bad since that’s what start me going down the rabbit hole I don’t know how to test it… then a mechanic told me 2 pins were out on the PCM and he put them in. So I’m down the rabbit hole …battery 100% not sure about coil or ground on coil I can’t get anyone to listen to me on that I heard from an instructor on youtube say that… no fuses are popped so I’m guessing not a short but a ground issue.


#20

I hate them too!!! I’m down a rabbit hole with no communication with the OBD 2 port car can’t read codes and a mess and willing to bet it’s a ground in the PCM for the 02 sensors that’s where I entered the rabbit hole uhhhhggg