This fella knows what he's talking about, he really helped on my jeep. Never just replace a part, always check it first.

 

I believe I noticed in the FSM (could be wrong) that the the Injectors will get a pulse for 3 secs...if the crank sensor is dud, this will then go out...another way to possible test for failed crank sensor ?

 

There is definitely something happening like that with the fuel system. I read it was 10 seconds though, and that it was something with the fuel pump which gets shut off when the engine does not fire due to a dud CkPS. I don't know from what source I got the information? It was not from out of the FSM though..

 

You probably got that from me. The PCM will not energize the ASD or fuel pump relay until it gets a signal from the CkPS telling it that the crank is turning, as in trying to start. It will also drop out those relays if the CkPS signal is lost. (ASD = Auto ShutDown relay) The moment the PCM is energized with the ignition key, a 2 second signal turns on the fuel pump relay to charge the fuel rail. Then it shuts off. The ASD relay energizes both the ignition and injector circuits.

Another thing a lot of people get wrong. The cam sensor has nothing to do with spark timing. It tells the PCM which INJECTOR to fire and when.

Remember when doing diagnostic work, Both the injectors and coil(s) are powered with 12v constantly, but only when the ASD relay is energized. Digital drivers in the PCM will ground an injector to fire it, but un-ground a coil to get it to spark.

 

So i found a picture earlier on the forum of the fuse box under the hood showing some fuses which have no labels(we thought they were spares before finding the pic) and found one that was blown changed the blow fuse and it started right up.

So we now feel a bit stupid lol but now the jeep has all new crank and cam sensors new coil pack and new tps and new pcm. and it dosent miss fire anymore like it did orginally after the pcm relearning

 

I became curious about this..

I just watched a short video. The video was for a Ford. However, the guy specifically stated that what he was doing applied to Chrysler vehicles as well.. He had the test light back probed to the fuel injector while chasing a suspected CkPS fault causing a crank - no start - no spark. During the whole time while cranking there was no injector pulse any at all. He explained this is further indication of having a bad CkPS, and about the shared trigger mechanism of the Ignition Control Module for the sparks etc...

Something I thought was interesting. During the cranking period the actual cluster gauge RPMs do not increase any to go up into the 100 - 300 RPMs as how it is actually happening during the crank to start time period. You can see these RPMs happening with using a live data stream tool because of the data pin pick-up for the CkPS. The thing that I thought was cool was about the Check Engine Light (CEL). The CEL comes on and stays on if you leave the ignition key turned on in the run position as a way of signifying the bulb works and the self-tests were successfully accomplished. Another way to test for a bad CkPS is by watching the illuminated CEL while cranking. If the PCM is recieving a signal from the CkPS, the CEL will go out during the cranking timeframe. If no signal is being received by the PCM from the CkPS.. then, the CEL will remain illuminated the whole time while cranking. I thought that is a really cool simple thing to be aware of as just another way of being able to differentiate between possible problems...

 

Yeah, you do have some new parts now! I am glad you were able to find the reason either way though.

 

Lol yeah, Thanks for the help

Now the next step is to figure out if it actually has low oil pressure or if its the oil pressure sending unit

 

Austin, hindsight is always 20/20, but wouldn't it have been nice to find that fuse before you changed all those parts? It's probably the ASD relay fuse that you shorted out.

Noah, good catch on the CEL! Problem is it will stay on if there are any codes stored.

 

We change the asd relay and asd fuse first thinking it was those. it was actually the ign rail coil and fuel injector fuse thats one of the tiny fuses in the fuse box. Which from google searches we never found where that fuse was exactly until last night when i had nothing to do and just went through like 30 forum posts till i found a image

 

Yes, that's a problem. Even the FSM doesn't name the fuses, just tells what circuit number it is. Then you have to go thru the circuit number list and figure out what is on that circuit by looking at the wiring diagrams.

Another thing on our jeeps (2000) is there is no direct connection between sensors and the gauges. All the information shown on the gauges is processed thru the PCM, then displayed.

 

Hang onto those old sensors just in case. You know about those non-mopar ones...

 

Yeah we have kept everything since if something may go bad the old stuff might be good

 

You know... I went back and thought about all of the things we could have done differently for a better outcome. Someone once said, "hindsight is 20/20"

I should have probably taken the time to type up a sixth complete paragraph (only on fuses).. to really get the point across about the importance of checking all of the fuses! In the end, this may have saved some precious time from being wasted?

I'm just messing around. I thought it was funny! It was really all awg's fault. He should have went on to write at least one more full post to mention testing all of the fuses again for you, you know?

I bet you are really glad the Jeep is starting and running again! I love it when that happens! Thank you for letting us know what it was...

Take care,
Ian (aka - Noah911)

 

Doesn't AWG stand for American Wire Gauge? ROTFL!