First time SKIM problem?

[seafish]

Earlier today, I started Giddyup (fully warmed up from running many errands) and was about to put her in gear and drive off and she suddenly died...just cutoff ... she would still crank hard but NOT restart.

As she has never done anything like it before, I was startled and while I did see the red SKIM led come on while turning the key, I didnt pay much attention to it as I was also looking at all the other lights, including the check engine light, which was now lit.
I also popped the hood and cowl, looking for any signs but found nothing obviously amiss.

However, while I was standing by the DS door calling my daughter for a potential long range rescue, I heard a soft clunk (more then a simple relay click) from near the fuse box, or perhaps ECM, and when I tried her again, she more or less started right up.

I finished running my errands and got home without any further incident but when I hooked up the OBD2 reader to check for DTCs, there were no codes set in memory.

I am guessing that something is starting to go amiss with the SKIM module cutting off fueling and I am open to any and all suggestions on how to proceed with diagnostics and fixes to prevent this from happening again!!!

Also specifically wondering --

1) if it could be something as simple as replacing the key fob battery?

2) what is the relay that I heard reset and where exactly is located?

 

[KJowner]

The battery in the fob is for the push buttons, the key has a small transponder built-in, it's powered by the radio transmission from the SKIM so has no battery.
I'd change the fuel pump relay just in case it's getting sticky and keep an eye on the dashboard lights to see if the immobiliser plays up again.

 

[lfhoward]

I am not sure on the KJ, but on the KK at least, the Jeep will start up fine and then die in about 2 seconds without the proper transponder signal from the key. Where yours wouldn't fire up at all, I would suspect something other than the SKIM module. But again, I am not sure if the KJ behavior would be different.

Also, as @KJowner mentioned, the battery in the fob is not needed for the transponder key to function. It just does the remote locks, etc.

 

[seafish]

Thanks for clarifying that the key fob battery cannot be the problem.

Still wondering what the soft "clunk" that I heard might have been and if it is likely related to the crank/no start condition as she started up right after I heard the noise.

Also still wondering if the SKIM activating would set a readable code in memory.

 

[blackhawk]

I am not sure on the KJ, but on the KK at least, the Jeep will start up fine and then die in about 2 seconds without the proper transponder signal from the key. Where yours wouldn't fire up at all, I would suspect something other than the SKIM module. But again, I am not sure if the KJ behavior would be different.

Also, as @KJowner mentioned, the battery in the fob is not needed for the transponder key to function. It just does the remote locks, etc.

Right, in my it's just like that

 

[seafish]

^^^

OK, I got it now...You guys are saying that, at least on a KK, with a bad SKIM signal it will simply restart immediately and then keep dying after 3 seconds unitl the SKIM is resolved.

Anybody know if the KJ CRD SKIM behavior is different then that??

 

[KJowner]

^^^

OK, I got it now...You guys are saying that, at least on a KK, with a bad SKIM signal it will simply restart immediately and then keep dying after 3 seconds unitl the SKIM is resolved.

Anybody know if the KJ CRD SKIM behavior is different then that??

Yes it's exactly the same, that's why I suggested you might have a sticky relay, especially after you heard it click and then everything worked.

 

[seafish]

A guy on LostJeeps is suggesting that the clunk I heard is likely the intake throttle opening up under spring pressure after closing on key off for engine shutdown. I will verify this later today by starting the engine, then shutting down and listening for the sound that I heard when the engine was not starting.

Perhaps more importantly, He is also saying that the crank/no start is likely from a failing, heat soaked crankshaft position sensor.

While he may be right about the former, I dont see how the latter interpretation fits the bill as the engine died when started after she had sat and rested for an hour.

That said, it is the original CPS with 200k on it...

Opinions??

 

[seafish]

ALSO, wouldn't an intermittent failing CPS set a DTC ??

 

[KJowner]

No, the ecu just thinks the engine isn't turning so no code, I've had it on my CRD, driving along happily, stopped to pick up my daughter, car won't restart until it cools down, I was busting for a wee too!
It's a fiddle to replace, behind the exhaust downpipe.

 

[seafish]

I've had it on my CRD, driving along happily, stopped to pick up my daughter, car won't restart until it cools down,

PLEASE clarify as this is important to me right now as I am planning a day trip with my daughter too and do not have time to buy and replace the CPS right now.

...it seems that you are saying that if in fact it is the CPS causing a no start, the engine will NOT simply quit while driving down the highway, but rather might only cause a no start when stopped ... which I can compensate for by NOT shutting down at breaks and simply leaving one of us at the wheel.

TIA!!!

 

[seafish]

Confirmed that the soft clunk I heard was the likely the intake throttle opening up after shut down...still not sure about why she started up right after that happened ... unless the "cooling down" time for the CPS aligned or overlapped with the intake reopening.

That said, I didn't even know that the intake had a plate worked like that, though it makes sense to help prevent "dieseling" after shut down which I understand is its purpose.

OR MAYBE .... that plate was sticking shut which is actually why she quit about after starting??

That does NOT seem likely, but could it be??

 

[KJowner]

Sorry I can't guarantee that the CPS won't drop out as you are driving, when they get old they don't like heat (no idea why!) And often won't let you restart until the engine has cooled a bit.
Different car but long ago my wife had a BMW, it would run for 20 minutes or so until the CPS heated up, then it would cut out until it cooled, it was a slow journey home!
If you buy one make sure it's a genuine Bosch one, probably worth doing the cam sensor too while you're at it.
Ignore the bit I put about fuel pump relay above, I thought you had a v6! Obviously no relay on the diesel unless you have added one!

 

[seafish]

If you buy one make sure it's a genuine Bosch one, probably worth doing the cam sensor too while you're at it.

Thanks for the advice!!!

I cant find the Bosch here and the even the boutique import parts house that I use and trust sells the Standard Motor Products crankshaft sensor. I have been somewhat impressed with the quality of SMP ignition parts and sensors that I have been using so far. Totally agree on replacing the camshaft sensor at the same time.

Got both from Rockauto for $76.00 delivered which is a dam good price since the camshaft sensor was on "wholesaler closeout" for $26.

ALSO included a Standard relay for the ASD to keep as a spare just in case that is getting sticky.

For reference, the part numbers are"

SMP #PC766 Crankshaft Position Sensor
SMP #PC644 Camshaft Position Sensor
SMO #RY438 5 pin relay