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Intermittent No Start Problem with Replacement PCM

 
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  #1 (permalink)  
Old 15 Jul 2015, 05:25 pm
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Join Date: Jul 2015
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Default Intermittent No Start Problem with Replacement PCM

Hello, I'm new to this forum and PT Cruisers and am having an intermittent starting problem with the security dot on the dash staying on. Sometimes the vehicle starts, sometimes it doesn't.

Here is some background information on the situation. My daughter recently acquired Gramma's 2002 PT Cruisers with roughly 126k on it. The car is in great shape but after a few months was throwing a p0601 code.

I bought a re-manufactured Cardone PCM (following 2 failed attempts with AllComputerResources) and sent the Cardone PCM, Immobilizer, and chipped grey key (key 2) to an electrical diagnostics company in Oregon to program the PCM to work with the key and immobilizer. I installed all the parts and the car worked great the first day with no codes. My daughter drove the car around town using her key (key 1) and I drove it later that day using the spare key (key 2 that was sent to the company).

On the following day (day 2), the car would not start in the morning using key 1 which was tried first or with key 2 which was tried afterwards. The lights, radio, and dash where working, but the starter was silent and would not crank. The starter relay showed voltage, but I did not check to see if the solenoid trigger had voltage. The red immobilizer dot on the dash flashed and then stayed on red while trying to start. The battery showed 12.25 volts. I tried the key dance and could not get a code or a "done" reading on the dash. It didn't seem to do anything. I did hold the odometer button to activate the self diagnostic test which seemed to work. In the afternoon when I came back to the car to do some more testing, the car started fine with key 2. I turned the car off and on multiple times and everything was working again at this point. I hadn't really fixed anything so I didn't know how to account for this. I hooked up an OBD reader and it showed no codes.

Today (day 3), the car would not start again in the morning using key 2 with the same symptoms as the morning of day 2. I tried shifting through the gears and starting in neutral, but this did not seem to help.

I have not has much time to play around with this issue since, but I have a few questions.

1) Can the immobilizer/PCM prevent the starter from cranking? I thought if the immobilizer was not happy (red dot stays on), the engine cranks and runs for 3 seconds before it stops (at least initially before it goes into some lockout mode). This is what I experienced with one of the failed PCM replacement attempts. I did measure voltage to the starter relay, so the interruption to the starter must be between the relay and starter or in the starter.

2) If the immobilizer can not prevent the engine from cranking, what failure could possibly cause both the immobilizer to not be happy and the engine not to crank? I would suspect a bad/intermittent starter if the immobilizer light was not also staying on. I find it very strange that each time the engine fails to crank, the immobilizer light is also staying on.

3) What could cause intermittent problems with the immobilizer?

I've cleaned battery connections and the ground in the engine bay and tried banging on the starter a little while starting it. My next step is to try and test voltage to the starter trigger wire when it is not starting, but I expect this to be zero.

Any input or suggestions would be greatly appreciated.

Thanks.
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  #2 (permalink)  
Old 15 Jul 2015, 05:47 pm
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Join Date: Jan 2014
Location: SW PA
Posts: 1,344
Default Re: Intermittent No Start Problem with Replacement PCM

Quote:
Originally Posted by struppi View Post
Hello, I'm new to this forum and PT Cruisers and am having an intermittent starting problem with the security dot on the dash staying on. Sometimes the vehicle starts, sometimes it doesn't.

Here is some background information on the situation. My daughter recently acquired Gramma's 2002 PT Cruisers with roughly 126k on it. The car is in great shape but after a few months was throwing a p0601 code.

I bought a re-manufactured Cardone PCM (following 2 failed attempts with AllComputerResources) and sent the Cardone PCM, Immobilizer, and chipped grey key (key 2) to an electrical diagnostics company in Oregon to program the PCM to work with the key and immobilizer. I installed all the parts and the car worked great the first day with no codes. My daughter drove the car around town using her key (key 1) and I drove it later that day using the spare key (key 2 that was sent to the company).

On the following day (day 2), the car would not start in the morning using key 1 which was tried first or with key 2 which was tried afterwards. The lights, radio, and dash where working, but the starter was silent and would not crank. The starter relay showed voltage, but I did not check to see if the solenoid trigger had voltage. The red immobilizer dot on the dash flashed and then stayed on red while trying to start. The battery showed 12.25 volts. I tried the key dance and could not get a code or a "done" reading on the dash. It didn't seem to do anything. I did hold the odometer button to activate the self diagnostic test which seemed to work. In the afternoon when I came back to the car to do some more testing, the car started fine with key 2. I turned the car off and on multiple times and everything was working again at this point. I hadn't really fixed anything so I didn't know how to account for this. I hooked up an OBD reader and it showed no codes.

Today (day 3), the car would not start again in the morning using key 2 with the same symptoms as the morning of day 2. I tried shifting through the gears and starting in neutral, but this did not seem to help.

I have not has much time to play around with this issue since, but I have a few questions.

1) Can the immobilizer/PCM prevent the starter from cranking? I thought if the immobilizer was not happy (red dot stays on), the engine cranks and runs for 3 seconds before it stops (at least initially before it goes into some lockout mode). This is what I experienced with one of the failed PCM replacement attempts. I did measure voltage to the starter relay, so the interruption to the starter must be between the relay and starter or in the starter.

2) If the immobilizer can not prevent the engine from cranking, what failure could possibly cause both the immobilizer to not be happy and the engine not to crank? I would suspect a bad/intermittent starter if the immobilizer light was not also staying on. I find it very strange that each time the engine fails to crank, the immobilizer light is also staying on.

3) What could cause intermittent problems with the immobilizer?

I've cleaned battery connections and the ground in the engine bay and tried banging on the starter a little while starting it. My next step is to try and test voltage to the starter trigger wire when it is not starting, but I expect this to be zero.

Any input or suggestions would be greatly appreciated.

Thanks.
By experience, the immobilizer will let the car start momentarily 3 times with the incorrect key then lock out. The red light will then come on and I believe stay on with the key turned to the on position

Are you sure your problem is not the key switch or related item.
try pushing in on the key to start it?
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  #3 (permalink)  
Old 15 Jul 2015, 08:16 pm
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Join Date: Aug 2014
Location: Thousand Oaks, CA
Posts: 7,308
Default Re: Intermittent No Start Problem with Replacement PCM

I have not tried this method. I know of some other members that have had luck using this method

Try opening the rear hatch with the chipped key. This is the method to disarm the factory alarm on several Chrysler makes, though I'm not sure if it applies to the PT. Use the chipped key for your starting attempts. If that fails, and you have not already done so, use the fob to lock and then unlock all the doors, then use the chipped key to do the same.

Let me know if this method works for you.

Last edited by ptcruisersteve; 15 Jul 2015 at 11:38 pm.
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Old 15 Jul 2015, 09:51 pm
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Join Date: Jul 2015
Posts: 7
Default Re: Intermittent No Start Problem with Replacement PCM

Okay, so today (day 3) in the evening, the PT Cruiser starts again without issue using both keys.

So now twice I could not get the Cruiser started in the morning (no crank at all) and twice I had no issues starting the Cruiser repeatedly later in the day. I'm starting to suspect temperature or humidity, but I'm in Southern California and nights are not that cold right now.

One thing that I noticed, if my memory is correct, is that when the Cruiser does not start in the morning, the immobilizer light blinks and then stays on solid.

When the Cruiser is running, if I use a non chipped key to start the engine (dies after 3 seconds), the immobilizer light flashes, but never stays on solid.

If I use non-chipped key repeatedly and go into lockout mode, the engine no longer cranks and the immobilizer light flashes, but does not stay on solid.

If I disconnect the immobilizer, the engine also starts (dies after 3 seconds), but the immobilizer light does not come on at all.

The PCM must be interpreting these situations differently. It must mean something when the immobilizer light blinks and then stays on solid? This seems to be unique to the no-start case in the morning and I can't recreate it. I thought if I could recreate it, this would be a clue.

I also noticed that if I get into lockout mode (won't crank) with the non-chipped key, the car starts without issue immediately using the chipped key. I did not have to wait for the system to time out of lockout mode or reset the system in anyway.

I found a diagram of the starting circuit and there is nothing between the starting relay and the starter to prevent the engine from cranking. It seems that if the starting relay is getting power, then the starter should crank if the starter is okay. This does not match with what I observed on day 1, so I will have to recheck this once the car is not starting again.

If the Cruiser does not start tomorrow morning, I will try opening the trunk with the chipped key to see if that changes anything.

Thanks for the responses.

Edit: I read something about the hood circuit being related to the solid light.

Last edited by struppi; 15 Jul 2015 at 10:00 pm.
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  #5 (permalink)  
Old 15 Jul 2015, 10:32 pm
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Default Re: Intermittent No Start Problem with Replacement PCM

I think your thinking too much about the immobilizer light...JMO
If the car starts at night but not during the day when it's hot, something is overheating...battery, bad grounds...dunno.
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Old 15 Jul 2015, 11:29 pm
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Default Re: Intermittent No Start Problem with Replacement PCM

The car does not start in the mornings around 8 or 9 (cooler from the night), it starts later in the day around 4 or 5 (warmer from the hot SoCal day). It probably starts earlier in the day as well (pretty hot here by noon time), but I just haven't tested it). Maybe there is a bad electrical connection when things are cool that gets better when the system warms up and things expand.

I found this in the service manual:
"Afterwards, if the bulb remains on, this indicates a problem with the electronics. If the bulb begins to flash after the bulb check, this indicates that an invalid key has been used to start the vehicle."

"If the light comes ON and stays ON solid after the indicator light test, this signifies that the SKIM has detected a system malfunction and/or that the SKIS has become inoperative"

My bulb stays on and I fear there is an issue with the PCM which is sensitive to temperature. I doubt the immobilizer or key are faulty since this problem is brand new. I originally replaced the PCM due to a P0601 code, but the car always started.
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Old 16 Jul 2015, 05:04 am
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Default Re: Intermittent No Start Problem with Replacement PCM

Quote:
Originally Posted by struppi View Post
The car does not start in the mornings around 8 or 9 (cooler from the night), it starts later in the day around 4 or 5 (warmer from the hot SoCal day). It probably starts earlier in the day as well (pretty hot here by noon time), but I just haven't tested it). Maybe there is a bad electrical connection when things are cool that gets better when the system warms up and things expand.

I found this in the service manual:
"Afterwards, if the bulb remains on, this indicates a problem with the electronics. If the bulb begins to flash after the bulb check, this indicates that an invalid key has been used to start the vehicle."

"If the light comes ON and stays ON solid after the indicator light test, this signifies that the SKIM has detected a system malfunction and/or that the SKIS has become inoperative"

My bulb stays on and I fear there is an issue with the PCM which is sensitive to temperature. I doubt the immobilizer or key are faulty since this problem is brand new. I originally replaced the PCM due to a P0601 code, but the car always started.
Was the PCM programed with your key..??
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Old 16 Jul 2015, 08:34 am
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Default Re: Intermittent No Start Problem with Replacement PCM

Quote:
Originally Posted by LionPT View Post
Was the PCM programed with your key..??
LionPT
I think you missed this part.

sent the Cardone PCM, Immobilizer, and chipped grey key (key 2) to an electrical diagnostics company in Oregon to program the PCM to work with the key and immobilizer
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Old 16 Jul 2015, 09:46 am
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Default Re: Intermittent No Start Problem with Replacement PCM

Quote:
Originally Posted by struppi View Post
The battery showed 12.25 volts.
Any input or suggestions would be greatly appreciated.

Thanks.
not saying this has anything to do with your issue, but i was taught under 12.4 it should be replaced. you may at least want to have it load tested when the car is drivable.
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Old 16 Jul 2015, 11:18 am
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Default Re: Intermittent No Start Problem with Replacement PCM

Today is day 4 and the car started in the morning around 8:20. This is the first morning start all week. The min temperature last night (58F) and temp profile was the the same as previous nights. The dew point was maybe slightly higher on average.

This breaks the pattern. I did disconnect and reconnect the immobilizer the day before during my testing and I also left the plastic guard around the steering column off overnight. I did not change anything else.

I will take the battery in to have it load tested when I get a chance. The car has been sitting for at least a month during this ordeal. It was only driven around a little on one of the days (day 1). When the car does start, it does not seem like a weak start. To add to this, when the car was running, the OBD reader reported a running voltage around 13.4 or 13.6 which also seems a little low. I think that should be in the 14s, but I'm not sure if that is effected by the lower 12.25 reading.

Thanks for the responses.
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