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cayenne pcm wont turn on with key turned


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hi guys, i'm having a bit of an issue with my cayenne 04 pcm unit. when i switch to the ignition the pcm doesnt wake up or switch off with the key , but if i press the power button on the pcm, it will come on but only for 15 minutes then it switches off. i have also noticed that the steering controls don't work ever. i have just checked all the fuses they are all ok. i have read up that pcm unit wakes up by can bus. i need help 

thanks troy

Edited by troyporsche
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  • 2 months later...

Hi there,

 

 

I have the same issue with my car in Hong Kong.

 

When I put my key in, the pcm switch on automatically and everything works fine including the steering button control. But when I turn the key to the positon of ignition, either with really starting the engine by applying brake or not. The pcm switch off. I can switch on the pcm while driving but it can only work for awhile and says it works under engine off status, and the camera is not connected and the steering button not functioning. Any idea whats going on? It works well before just after the starter motor getting changed today. My technician said he just disconnected the batt during the work.

 

Thanks

Terry

Edited by Cyttse
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1 hour ago, Cyttse said:

Hi anyone can help??

 

I tried dial 148 but it doesnt work after reboot.

 

How to reset the pcm??

 

 

Thanks

 

Terry

Try this unlock car and get in shut door don't insert key or turn on kessy Dummy key if you have one. Wait 1 minute and then press 1 4 8 simultaneously and hold for 10 seconds then release, wait for 1 minute. Then try to turn on pcm if it didn't already reboot.  If on then turn off and exit vehicle and lock. 

Re- enter start car normally and check pcm if it will work correctly. 

If not try the method attached. 

 

Assume your battery is good and no water in fuse boxes or in foot well under carpet wires broken or corroded? 

 

If all fails then maybe pcm is fudged. 

 

Good luck. 

Screenshot_20170105-221420.png

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Thanks!

 

 

Will try later and hope it works.

 

 

By the way, will the problem related to anything about changing starter motor? The battery was disconnected for a couple hours before and all this happened.. does the pcm needs any coding after disconnect the batt?

 

 

Hi anyone can help??

 

I tried dial 148 but it doesnt work after reboot.

 

How to reset the pcm??

 

 

Thanks

 

Terry

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8 hours ago, Cyttse said:

Thanks!

 

 

Will try later and hope it works.

 

 

By the way, will the problem related to anything about changing starter motor? The battery was disconnected for a couple hours before and all this happened.. does the pcm needs any coding after disconnect the batt?

 

 

Hi anyone can help??

 

I tried dial 148 but it doesnt work after reboot.

 

How to reset the pcm??

 

 

Thanks

 

Terry

I've disconnected my battery many times and haven't needed to do anything to the pcm. 

I've also removed and rebuilt my starter motor and replaced alternator for that matter and nothing I can think of should directly or indirectly cause a pcm problem. 

I think the pcm issue is a result of disconnecting the battery only. 

What brought around the need to change the starter motor?

Have you confirmed your battery is good? (at least 12.6 volts engine off ignition off) and charging voltage engine running at idle and any speed stable 13.7-14.2 volts? 

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I have tried both of the methods but it seems not work..

The starter motor not working well therefore I need to change it. And I did change the headlamp ballist at the same time but without correctly coding it yet ans therefore there is still fault code of headlamp on the dashboard. 

Checked all the related fuse but they are all good.

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  • Admin
7 hours ago, Cyttse said:

Is that I need to enter the code for the pcm and how can I find it?

 

" Can you give me a code for my PCM?
These units are manufactured jointly by Siemens and Becker, and the only place where you can get the codes required is from the dealer/ OPC. The PCM’s require two codes, the ICS/Siemens code and a Becker code. The ICS is the first code requested.
Sorry, the only place you can get a PCM code is from a dealer/ OPC".

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5 hours ago, troyporsche said:

im still having the same issue with the pcm :angry: its just annoying now. cant listen to music more than 15 min with out it switching off , 

this issue started after the battery was changed. im thinking of replacing the pcm with a chinese unit on ebay.

 

help please :cursing:

 

Can you use the steering button when the key not turning to ignition? Is the navi working?

  • Upvote 1
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I had the exact same issue, took it in to the dealer, they couldn't figure it out and wanted me to replace the pcm. I also read every post I could find on the forums and in the end I bought a new battery and that fixed the problem.


Sent from my iPhone using Tapatalk

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31 minutes ago, Saadi996tt said:

I had the exact same issue, took it in to the dealer, they couldn't figure it out and wanted me to replace the pcm. I also read every post I could find on the forums and in the end I bought a new battery and that fixed the problem.


Sent from my iPhone using Tapatalk

Cytte refer to my previous post you must be 110% sure the battery is in top shape or you are chasing your own a*s around in a circle. 

 

Use a battery maintainer for a night and check it in the morning, or just replace the battery if it doesn't check out. 

 

You know when I had a no start situation I strip out my starter and found it to be fine, but I stripped it completely down cleaned up everything, bench tested and put it back togther. I subsequently found the alternator was jammed causing the no start. But anyway the point I'm making is after I got it all Fixed the car started so much better because I had simply cleaned up the starter motor internals, brushes and all cable connections reducing the resistances. 

 

This car is the worst for anything remotely voltage drop related. As the winter has come more and more people have posted with weird stuff happening and quite a few just needed a new battery (but not all). 

 

Cytte is it possible your worn but working starter was affected by your possibly failing battery? Maybe just a new battery and a starter clean up would have been a Fix as opposed to a new starter which will run on the failing battery because it's new and has less internal resistance? Alot of maybes I know but you gotta think outside the box a little when faced with these conundrums. 

 

Maybe your pcm is fudged and I'm talking nonsense. 

 

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11 hours ago, troyporsche said:

 

 

2 hours ago, lewisweller said:

Cytte refer to my previous post you must be 110% sure the battery is in top shape or you are chasing your own a*s around in a circle. 

 

Use a battery maintainer for a night and check it in the morning, or just replace the battery if it doesn't check out. 

 

You know when I had a no start situation I strip out my starter and found it to be fine, but I stripped it completely down cleaned up everything, bench tested and put it back togther. I subsequently found the alternator was jammed causing the no start. But anyway the point I'm making is after I got it all Fixed the car started so much better because I had simply cleaned up the starter motor internals, brushes and all cable connections reducing the resistances. 

 

This car is the worst for anything remotely voltage drop related. As the winter has come more and more people have posted with weird stuff happening and quite a few just needed a new battery (but not all). 

 

Cytte is it possible your worn but working starter was affected by your possibly failing battery? Maybe just a new battery and a starter clean up would have been a Fix as opposed to a new starter which will run on the failing battery because it's new and has less internal resistance? Alot of maybes I know but you gotta think outside the box a little when faced with these conundrums. 

 

Maybe your pcm is fudged and I'm talking nonsense. 

 

Thanks for your reply.

 

I had my new batt replaced in just 3months ago thats why I didnt think about that was related to the batt before. 

My starter seems working badly before as it needed more than 5 times to make it start. The new one seems working well now.

 

 

Anyway I ll try to measure the the voltage again tonight and see. Or I ll disconnect the batt for awhile.

 

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On 2017/1/7 at 8:01 AM, troyporsche said:

 

 

22 hours ago, lewisweller said:

Cytte refer to my previous post you must be 110% sure the battery is in top shape or you are chasing your own a*s around in a circle. 

 

Use a battery maintainer for a night and check it in the morning, or just replace the battery if it doesn't check out. 

 

You know when I had a no start situation I strip out my starter and found it to be fine, but I stripped it completely down cleaned up everything, bench tested and put it back togther. I subsequently found the alternator was jammed causing the no start. But anyway the point I'm making is after I got it all Fixed the car started so much better because I had simply cleaned up the starter motor internals, brushes and all cable connections reducing the resistances. 

 

This car is the worst for anything remotely voltage drop related. As the winter has come more and more people have posted with weird stuff happening and quite a few just needed a new battery (but not all). 

 

Cytte is it possible your worn but working starter was affected by your possibly failing battery? Maybe just a new battery and a starter clean up would have been a Fix as opposed to a new starter which will run on the failing battery because it's new and has less internal resistance? Alot of maybes I know but you gotta think outside the box a little when faced with these conundrums. 

 

Maybe your pcm is fudged and I'm talking nonsense. 

 

Thanks for your reply.

 

I had my new batt replaced in just 3months ago thats why I didnt think about that was related to the batt before. 

My starter seems working badly before as it needed more than 5 times to make it start. The new one seems working well now.

 

 

Anyway I ll try to measure the the voltage again tonight and see. Or I ll disconnect the batt for awhile.

 

 

 

Disconnected the batt for a night but no luck.

 

Will try put on a new batt or what next week. Annoying.

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  • 2 weeks later...
On 07/01/2017 at 5:27 AM, Cyttse said:

Can you use the steering button when the key not turning to ignition? Is the navi working?

hi sorry i have been driving my cayenne so i couldn't check my front wipers stopped working. and no my steering control don't work with the key ignition. i took the battery out to check and charge i notices the positive terminal was loose it came out with my hand. i wonder if that could be the issue. when i put the battery back i ll up date

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On 19/01/2017 at 3:19 AM, troyporsche said:

hi sorry i have been driving my cayenne so i couldn't check my front wipers stopped working. and no my steering control don't work with the key ignition. i took the battery out to check and charge i notices the positive terminal was loose it came out with my hand. i wonder if that could be the issue. when i put the battery back i ll up date

Another cayenne owner had steering wheel lights not working....... Ended up being the old battery giving up. New battery fixed it. 

Maybe having a loose terminal connection has also drained the battery beyond reliable use? Or a slow trickle charge for 12 hrs will bring it back to life and work normally possibly? 

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On 20/01/2017 at 9:02 AM, Cyttse said:

Your front wipers not working????

 

I have exactly the same issue as yours! I just found my wipers not working too but its not about the motor....

so weird...

thats so weird. do your front jet washers work? i had my mate put a diagnostic computer on the cayenne. no listing for the pcm module so i dont know if the pcm is being picked up by the can network , also tried accessing the wiper module no communication with module. i can access the other module. im going to replace the battery next week if that dont working im have to take it to dealer

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