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merwin10 12-14-2011 03:24 PM

4.7L Won't Start
Hi All need some help!

Ok here is the problem - Had a friend helping me on my 2002 jeep GC 4.7L, NOT the HO!

Well we were doing allot of work TPS, Brakes, Lighting problem, etc. Any way the engine ran fine once we replaced the TPS. (no More DTC codes). So he started the lighting issue! It got late and he left and the key was left in the run mode over night! So the next day I went out and notice it checked the battery it was down to 3.6 volts. Hmmm! So I charged up the battery all day, till the charger said full! (has a new battery 3 months ago). Anyway when I go to start it all the necessary lights light up on the dash, gauges come to life. Turn the key to start and all it does is crank over. Does not even try to start! I don't even know where to start looking. Loosen the injector rail, it is getting fuel, sounds like no spark!

Hope something did not burn up!

Any thoughts?


Mike -:eek:

Frango100 12-15-2011 05:08 AM

Re: 4.7L Won't Start
Did you check for DTC´s after the no start problem occured?
Did you check all fuses?

merwin10 12-15-2011 08:37 AM

Re: 4.7L Won't Start
Hi Frango -

Thanks for the response! Yes! I checked for DTC after the no start problem! NO DTC's There is power at the OBDII connector! After playing with it some more I did find something else! The SKIS (Sentry Key Immobilizer System) light is acting funny, never seen it stay on! Perhaps the SKIS is preventing the engine from starting. Boy how I hate all these SAFETY features, they just complicate matters! Funny how so many things are interconnected, one part breaks and effects 20 other systems! But I bought this WJ cheap so just have to work thru some issues!

Mike - :confused:

Frango100 12-15-2011 08:44 AM

Re: 4.7L Won't Start
Do you have a spare key to see if it will work with that one? Maybe a wire disconncted during the other trouble shooting procedures?

merwin10 12-15-2011 09:02 AM

Re: 4.7L Won't Start
Hi Frango

Unfortuneately no second key! Used car so keys are going to be a problem as I don't have the PIN number either! That means a trip to the Jeep dealer! SUK!

Mike - :confused:

Frango100 12-15-2011 09:22 AM

Re: 4.7L Won't Start
When the SKIS light stays on, the system indeed prevents the engine from starting. There is a kind of antenna ring aroung the ignition switch, did you do something overthere? When it was running in the beginning, there must have happened something. Did you check the fuses? Fuse 7 and 22 on the junction block under the steering wheel are for the SKIM.

merwin10 12-15-2011 09:39 AM

Re: 4.7L Won't Start
Hi Frango -

Did not touch the ignition switch other than to start the engine before the problem started! I will have to check the fuses 7 and 22!

Mike -

merwin10 12-15-2011 10:40 AM

Re: 4.7L Won't Start
Hi Frango -

Well you were almost right! Was not the SKIS after all, ever though the ligt was on, damn computers lead you wrong every time! Why the DCU turned on the SKIS light is beyond me! You mentioned checking 7 and 22 fuses so while there I checked a few more! Found a blown fuse, #12 Auto shut Down Relay / Fuel! Replaced the 10 amp fuse started right up and ran fine!

So now onto the next and last issue! I am showing a Stored DTC of P0770, which is a transmission issue with solenoid #4c. I am betting that once the TCM is cleared it will not reset the P0770! I believe it was realated to a TPS that I replaced, it was causing the engine to race in park and netural, it had a flat spot in it when back probed. Replaced the TPS no more racing and runs much better!

Thanks for your replies!

Mike - :cool:

Me Fix 12-15-2011 11:58 AM

Re: 4.7L Won't Start
Frango is in here all the time. One of the best friends we can all have. Knowledgable and very friendly with his helpful hints.

Thanks, Me Fix

Frango100 12-15-2011 04:45 PM

Re: 4.7L Won't Start
It is always a good start to check all fuses when an electrical system stops working without a known reason. Fuse 12 is indeed feeding the auto shutdown relay, as well as the fuel pump relay and is one of the power inputs to the PCM. And the SKIM............ no idea why it was switching the SKIS light on.
Thanks for the nice words Me Fix, i like to help others and its a hobby for me.

merwin10 12-21-2011 02:47 PM

Re: 4.7L Won't Start
Hi All -

Yep The p0770 was a stored event for some reason! Once we got it on the drbIII and cleared the TCM everything is back to normal!

You know it is so hard with all these computers and sensors that are tied together to run this or that! Been reading the 545RFE transmission manual and it is totally relying on the engine sensors to make decisions about the learning setup! There is even a Quick Learn that uses the TPS among other things that has to be at a particular percentage open setting for the quick learn procedure to work! What a pain!

Fortunately, I have a Chrysler tech with the borrowed drbIII. Boy they want big $$$$ for them!

Mike - :thumbsup:

TACFIRE325 01-10-2012 06:52 AM

Re: 4.7L Won't Start
Nice Information!! While I have a JGC 02 4.0 4x4, Had some of the same tranny issues. (Yeah! What a surprise...) Anyway, just wanted to post that even though the engines are different, the tranny link to the TPS sensor is still the same for the 4.0. I have had all kinds of issues & started replacing sensors, because the codes given. I even change the "Governor Pressure Sensor, in the tranny because of a P1762 error.

At my wits end I spoke to a friend of a friend & as I started telling him what was going on with the tranny issues, he cut me off & said change the TPS. I thought "This guy's nuts!" He picked up on the silence & said "I know you think I'm nuts, but replace it anyway. If it doesn't fix your problem, I'll buy the part from you for what you paid." He even said that P1762 code for the GPS in the tranny was probably a result of the bad TPS sensor.

Well, I did... & it did... & now it's running fine. Few other issues, but I know it is not the TPS causing it...

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