jay Cummings

2002 4.0 starts right up stops after 2-3 seconds I just replaced battery and cam shafts sensor.it had been sitting for six months.replaced fuel also.it sounds great when started but again dies without stuttering in 2-3 seconds like it was being turned off any ideas on what the problem might be. 118600 miles

89Laredo

Sounds like the security system acting up.

Thats about the extent of my knowledge of the security system.

Bustedback

Turn the key o the run position and pump the gas pedal three times, then start the engine.

Anthony Reed

dave1123

I definitely sounds like the security system. Do what Bustedback says!

Waterluvr

Sure sounds like your skim module is not seeing the key frequency at the antenna end or the PCM is corrupted and the SKIM isn't able to verify the VIN code over the PCI BUS when it starts.

Scan it for codes with something better than a generic OBD reader and it will tell you the failure point.

Jaybird508

I just fixed my 99 XJ. Broken ground in the driver door opening. Took out my dash gauges and anti theft.

dave1123

Yeah, it's either the SKIM not recognizing the key as valid or the PCM not receiving a signal from the crank sensor. The SKIM problem will show as a barred key symbol light on the instrument cluster. The crank sensor signal failure will just shut the engine down.

Jaybird508

My jeep ran great for three days and back to the same issue. Key alarm on the dash. Does anyone know of anything that would cause this besides a SKIM/ECU conflict? If not, has anyone switched out their ECU with one with that has the security feature turned down?

Waterluvr

"Turning off" the SKIM system by swapping the PCM is an internet myth if your Jeep is equipped with it, the PCM driver outputs are not on the same pins and the harnesses are totally different. The amount of money and labor hours to actually convert one would be prohibitive.

I can program a replacement PCM for you, make note of the part number on your PCM and grab one from a salvage yard from the same year and powertrain. When you lift the hood take note of the sticker just right of center that will show you if the emissions programming are compatible there's Federal and California models in yards just about everywhere.

As as alternative, if you can find the same make/model/year in a yard and the key(s) are actually still in the ignition that's a honeypot you need to get the PCM, SKIM module under the steering column and the ignition cylinder and keys then you can reinstall all of that on your Jeep and it's plug and drive. Grab the drivers door lock cylinder if you want one key to do it all the only issue you'll have is in emission testing states that read the VIN code from the PCM it won't match and you'll get flagged for it.

But you can always send the replacement PCM to me for programming after you drive on it a bit that way to get the original SKIM and VIN information programmed properly.

Jaybird508

Is there a specific test to see if it is the SKIM module or the PCU?

Waterluvr

Yes, and it requires OEM level diagnostic hardware to do it on the vehicle that leaves you with paying outrageous sums of money at the dealership or an independent shop in the unlikely event you find one that spent the coin to have OEM level tech on hand like I have it's really cost prohibitive outside the dealership to invest in those tools with any hope of recouping the cost your talking 3K plus just to have the ability to program modules and several more to be able to access the SKIM's for pin code retrieval and key programming ability.

I can test and program PCM's off the vehicle but in order to troubleshoot the SKIM module I have to have the vehicle here and plug the scanner into the OBDII data port to engage the bi-directional diagnostic tests so it can interact with the sentry keys and the PCM over the data BUS.

Junkyard parts are a life saver when you have issues like this you won't be into it worse case scenario for more than a couple hundred bucks all in with parts and programming, you don't even want to see what stealerships charge to diagnose and replace those components it easily exceeds the value of the vehicle in most cases.

As I said before if you can find the PCM, SKIM, keys and lock cylinder in a yard grab them! It's all plug and play to swap them that is in no way the typical behavior of firing a parts cannon at an electrical related issue it's the cheapest and fastest way to get back on the road without paying some serious diagnostic fee's to a dealer.

Most yards charge between $15.00 to $35.00 for a PCM/ECU and if you make the argument that the keys, skim and cylinder are all paired once and forever to the PCM (and they are since that's how the security system works) they may not charge any more for them. Even if you have up to 150.00 in all of that it's the cheapest way out you can find doing it all yourself at home.

If you want to try just a replacement PCM I can help you with programming it send me a PM and we can work out the details, I do two at a time for lots of Jeep owners and shops because it doesn't cost anything more to program a second module so long as it's done together the same day.

I carry a spare PCM in my WJ, think of what would happen on a long trip if your module needed to be replaced!

Also, avoid any of the usual suspects that sell repaired or refurbished PCM's on the internet those crooks are just selling you someone else's problem and they never last long if at all your safest bet is using an unmolested module from a yard there are no new ones available anywhere so better to stick with one that hasn't been a problem child already.

Reekor

This *** clown is all over the internet spreading his gospel of bullchitness. This guy is on a mission to make the world as stupid as him.

The PCM hardware is the same with or without SKIM. The SKIM code can be edited out so that there is no SKIM needed. To enable SKIM simply install a SKIM and the SKIM will marry itself to the PCM.