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Discussion Starter #1
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?

thanks

Mike -:eek:
 

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The beast from Brazil
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Did you check for DTC´s after the no start problem occured?
Did you check all fuses?
 

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Discussion Starter #3
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:
 

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The beast from Brazil
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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?
 

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Discussion Starter #5
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:
 

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The beast from Brazil
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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.
 

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Discussion Starter #7
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 -
 

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Discussion Starter #8 (Edited)
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:
 

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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
 

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The beast from Brazil
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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.
 

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Discussion Starter #11
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:
 

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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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Discussion Starter #13
Yea! The way things are on these cars the sensors are tied to many unrelated functions, such is the TPS. The one issue that we will never know is what the intent of the engineer was when they wrote the computer test function that gives you the DTC codes. The codes can lead you down the wrong path. Who would of thought that the TPS would effect the transmission even though the engine is running fine! I think one thing I can say about the TPS test is that the test does not check for the TPS linear function (true percentage of throttle opening!). Even the shop manual does not explain the testing function intended!

As you found out the TPS does effect the transmission shifting as does the temperature of the transmission oil, stays in third till the oil is up to temperature, then shifts to 4th and 5th gears.

Mike -:thumbsup:
 

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Just want to say brilliant. You guys are amazing.
I had the same issue on my 01 GC 4.7 would crank and not start.

So for any one else struggling with the crank not start first check fuse 12 under the steering column it's a red 10amp fuse just above the airbag fuses.
 

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I know I'm late to the party, BUT if ya still having this issue, check the for corossion on the batery terminals and posts, also, check alternator juice, last but not least, disconnect battery for about 5 minutes, then reconnect. Also check the battery harness wires, they maybe broken (crumbling) and or covered with corrosion also.
I've had to do this several times, more so when its been way to damn or extremely humid, before I replaced the entire battery harness cables.
 

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You said in the initial post you had fuel which can throw people off. You weren't getting fuel if the pump was not running. Glad you got it fixed.
 
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