It's 2:26am Do you know why my car wont start?

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johnparts

johnparts

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I do. Ok guys if you are going to be running a factory pcm that has been flashed before and was in a car please pay attention here this will only hurt for a minute. The factory system use a module that hangs out behind the ignition switch and it sends a signal to the pcm telling it whether or not it likes the SKIM signal. Now with our cars not having much in the way of computer systems in them there is obviously no module there to tell the pcm that a key is there.

SO here is where this gets kinda interesting. As long as the key is programmed to the SKIM it doesn't care what car it's in. How do I know this well my pcm finally got completely wired tonight but wouldn't take my custom tune so I checked for codes and the one that stuck out like a sore thumb was P0633 Transponder Key not programmed. So I went into my tuning software and disabled the SKIM logic and guess what same result. Well I just so happen to have an 06 Magnum sitting right outside my garage door so I pulled his pcm out plugged mine in and began the tuning process to see if I could disable the skim on a car that the module was equipped with a programmed key and well guess what I didn't get a P0633 code so I figured I was good there is no way his key was programmed for my pcm so I'm good to hook the thing back up to my engine and see if she will turn over right? wrong Seems it doesn't care if it's programmed to the pcm just if it's programmed to the SKIM module.

SO thank you for reading my rant but I learned something I can now pass on to you all. Get a factory pcm and a pre programmed SKIM module and key and you are good to go without spending 1000 bucks on an aftermarket pcm. I'm going to scour ebay now for a SKIM/Key combo from cleveland pic a part thought I saw one last week for 30 bucks hope it's still there.
 
johnparts said:
I do. Ok guys if you are going to be running a factory pcm that has been flashed before and was in a car please pay attention here this will only hurt for a minute. The factory system use a module that hangs out behind the ignition switch and it sends a signal to the pcm telling it whether or not it likes the SKIM signal. Now with our cars not having much in the way of computer systems in them there is obviously no module there to tell the pcm that a key is there.

SO here is where this gets kinda interesting. As long as the key is programmed to the SKIM it doesn't care what car it's in. How do I know this well my pcm finally got completely wired tonight but wouldn't take my custom tune so I checked for codes and the one that stuck out like a sore thumb was P0633 Transponder Key not programmed. So I went into my tuning software and disabled the SKIM logic and guess what same result. Well I just so happen to have an 06 Magnum sitting right outside my garage door so I pulled his pcm out plugged mine in and began the tuning process to see if I could disable the skim on a car that the module was equipped with a programmed key and well guess what I didn't get a P0633 code so I figured I was good there is no way his key was programmed for my pcm so I'm good to hook the thing back up to my engine and see if she will turn over right? wrong Seems it doesn't care if it's programmed to the pcm just if it's programmed to the SKIM module.

SO thank you for reading my rant but I learned something I can now pass on to you all. Get a factory pcm and a pre programmed SKIM module and key and you are good to go without spending 1000 bucks on an aftermarket pcm. I'm going to scour ebay now for a SKIM/Key combo from cleveland pic a part thought I saw one last week for 30 bucks hope it's still there.
Click to expand...

Get me one too... seriously... I have no idea wtf you are talking about.... I have been dealing with these new hemis for years and have n't toughed the PCM stuff.... I just want to know if the truck PCM/ECU that I have in my possession will work, if not what do I need to make it work?
 
Get an 04 truck harness and I mean the key and the ignition switch with the skim module built into it and it needs to already be programmed
 
johnparts said:
ISeems it doesn't care if it's programmed to the pcm just if it's programmed to the SKIM module.
Click to expand...

Yes, but no.

Not only do you need a programmed Key, the VIN in the PCM and SKIM have to match.


Whatever SKIM you find, you'll need the VIN off of it programmed into your PCM. You'll need the SKIM's VIN# to ask the dealer for 4 digit PIN number to allow the PCM to be flashed with the new SKIM's VIN. A DRB-III factory scan tool is used to flash a used PCM with the matching VIN.

With a PCM, SKIM, SKIM PIN #, a transponder Key and a DRB-III, you can have it all programmed in about 10 minutes.


It would be wonderful if Diablo could get the SKIM switches to work.
 
Um yes but no the pcm I was using works in the magnum no problems without a matching vin being programmed in with a drb3 or a starscan as a matter of fact there was still a charger srt8 vin in the pcm I was using so there is no way the SKIM assumed it was a matching vin.

As long as the skim has been programmed to the key it will recognize the key and send a good/no good signal on the can bus. I have been through the FSM several times on this subject and there is no mention that the SKIM needs a vin programmed or a PIN assignment just that the rfid needs to be recognized by the module and it is very simply a go/no go switch signal.
 
johnparts said:
Um yes but no the pcm I was using works in the magnum no problems without a matching vin being programmed in with a drb3 or a starscan as a matter of fact there was still a charger srt8 vin in the pcm I was using so there is no way the SKIM assumed it was a matching vin.

As long as the skim has been programmed to the key it will recognize the key and send a good/no good signal on the can bus. I have been through the FSM several times on this subject and there is no mention that the SKIM needs a vin programmed or a PIN assignment just that the rfid needs to be recognized by the module and it is very simply a go/no go switch signal.
Click to expand...

So the mismatched PCM started and idled the car?

Kids with 2003-2005 SRT-4 swap PCMs(all NGC3) all the time but in every case, if the VIN in the PCM doesn't match the VIN in the SKIM, the engine will briefly start but then die(1-2 seconds).

I was certain it was the same deal for every NGC
 
so the way i understand it your saying the 05 truck engine harness and computer i bought won't talk to me without the matching vin and skim? i thought trucks didn't have a skim until later years
 
05 Might have skim depending on the trucks options.

The mismatched pcm ran idled and took a custom tune.
 
rapidtransitric said:
so the way i understand it your sayingthe 05 truck engine harness abd computer i bought won' talk to me without the matching vin and skim? i thought trucks didn't have a skim until later years
Click to expand...

Well I just purchased a 07 SRT Jeep harness and I want to use it with my 04 ECU out of a truck...
 
johnparts said:
The mismatched pcm ran idled and took a custom tune.
Click to expand...

There's a few of the details im missing.

What year was the Magnum?
What's the year and calibration ID of the Srt-8 PCM?

I've been going over the 06 LX service manual and although it alludes to mismatch PCM/VIN causing "Crank but Stall" condition its not real clear.
 
interesting....

Here's what the SRT-4 service manual states:
For added system security, each SKIM is programmed with a unique "Secret Key" code. This code is stored in memory and is sent over the PCI bus to the PCM and to each key that is programmed to work with the vehicle.

If a PCM is replaced, the unique ’Secret Key’ data must be transferred from the SKIM to the new PCM using the PCM replacement procedure.

I guess its possible that the LX cars might not have this "added security" feature.
So which methodology do the Trucks use?
 
myduster360 said:
interesting....

Here's what the SRT-4 service manual states:
For added system security, each SKIM is programmed with a unique "Secret Key" code. This code is stored in memory and is sent over the PCI bus to the PCM and to each key that is programmed to work with the vehicle.

If a PCM is replaced, the unique ’Secret Key’ data must be transferred from the SKIM to the new PCM using the PCM replacement procedure.

I guess its possible that the LX cars might not have this "added security" feature.
So which methodology do the Trucks use?
Click to expand...
Very interesting info I'm going to pick Dave at B&G and see if he disables that when he does his reprogramming.
 
I can see if I can get you the parts you need.

now the easiest way to go is get a ram pcm sithout the skim. That would solve all the problems. So let this be a learning thing for anyone that still needs to buy a pcm. But a ram pcm without the skim. With the tuning options now available, it's not an issue to run any hemi with one. And you don't need to hassle with all the speed sensor garbage that the cars have. To me it's a no brainer.
 
I'm talking when using the nag1 trans. You need wheel speed sensors to properly operate the trans. The older ram pcm's 03-05 rely alot less on speed sensors. So you have less headaches with the pcm going into limp mode. I don't know if the ram pcm will contol the nag1 but it might with some work. If your looking at a non compter controlled trans and you just turn the trans options off then there is not much to worry about. Another thing to think about is in 08 all cars/trucks came with traction control. And could pose another problem there. Research will be key. But an early pcm would be the best option
 
The NAG1 continues to have its own Transmission Control Module. So if the NGC pcm could run it, I'd think Chrysler would have done it by now.

All aspects of Torque Management (aka "traction control") can be turned off with a simple tune flash.

imo, aside from specific transmission control(if needed:545RFE) just getting a custom tune to configure the PCM to your specific needs is the way to go. No real advantage from hunting for a specific PCM.

Most A body Hemi swaps would benefit greatly from a custom tune anyway, just because headers are often used and the car is 1000lb lighter. A custom tune will bring the A/F in line, eliminate dreaded COT(cat over temp protection), raise the Rev limit, remove all Torque Managment, fine tune Timing and maximize performance overall.

Most stock truck and car can gain 10-20hp fairly easily with timing and fuel tweaks, how much would an abody/hemi gain?
 
I still say the truck pcm is the way to go. But it's just a diffrence of opnion. I am more comfortable with the trucks than the cars. And you seem to be more comfortable with the cars. Not a big deal. Turning everything off sounds easy in prinipal, but in functionality how easy is it? I have delt with the trucks for years, the cars I have done a bunch of work on, but never got into the electronics of them much. I'm going off the many hours spent looking at service manuals and through the many hours of reading on about 5 forums. I could be mistaken on every little detail. Going by your avatar you probably know more of the electronics than I do. As I'm not a tuner, but have worked on plenty of them to understand how most of it works. And I'll stick to the simplicity of the ram vs the lx when it comes to electronics.
 
03ramit1 said:
I still say the truck pcm is the way to go. But it's just a diffrence of opnion. I am more comfortable with the trucks than the cars. And you seem to be more comfortable with the cars. Not a big deal.
Click to expand...


Agreed. I guess my point is use what ever you have, truck or car, and just get a custom tune.

From a performance standpoint, most of the trucks generally have a pretty weak timing table.
 
So you guys are sayin' that the truck computer could be "tuned" to run alot better performance wise? I consider both of you (myduuster and ramit) to be my official guru's, so that is why I ask. I have an 03 truck set up, street&performance wiring harness, srt8 injectors, tti headerswith complete exhaust (x-pipe), billet spacers to run a car intake on the truck motor. Runs good in the garage, but should anything be done for when it finally hits the street this spring?
 
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