2003 Jeep Grand Cherokee - JeepForum.com
 
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post #1 of 12 Old 06-17-2019, 01:08 AM Thread Starter
Madmapper
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2003 Jeep Grand Cherokee

Randomly will not start had to several mechanics and a dealer they replaced ECM didnt fix the problem next thing they wanted to do was replace a transmission solenoid and wiring harness at $800 and wouldnt gaurntee that was the problem. So i brought home after messing around with it have discovered when it won't start sometimes if i press brake pedal first it will start not every time but if i turn ignition switch on and off and press brake it has always started after several attempts it starts sooner or later anyone have any idea what the problem could be.

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post #2 of 12 Old 06-17-2019, 01:27 AM Thread Starter
Madmapper
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Any help would be greatly appreciated trying to figure this out for my Daughter and her Husband Thanks again for any suggestions !
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post #3 of 12 Old 06-17-2019, 08:52 AM
LuthWJ77
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Somebody on here will be able to help but can you give more detail like it cranks but won't start or it won't crank either? Can you hear fuel pump turn on? etc etc. Also what engine you have. That'll help track down probably culprits.
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post #4 of 12 Old 06-17-2019, 10:42 AM Thread Starter
Madmapper
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2003 Jeep Grand Cherokee has the 4.7 V8 has a new starter new starter relay new ECM when it won't start will not turn over. The dash lights come on will not crank have narrowed down to putting foot on brake either while key is turned or turning key it will crank and start one way or the other. My first thoughts was the Shift Interlock Solenoid since it ties in with the brake light switch and neutral safety switch but I'm always able to get it out of park. Then next thing was neutral safety switch but the reverse lights work as well. I've googled this problem come a crossed few other people describing the same problem but haven't seen any fix for the problem. Also have read where this worked for a few months then it quits. I'm just afraid eventually pushing the brake trick is not going to work and leave them stranded.
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post #5 of 12 Old 06-17-2019, 10:44 AM
jtpeters
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No crank....Neutral Safety Switch ??

2004 Jeep Overland WJ 4.7 H.O. (Bought new in Oct 2003)
2014 Jeep Overland WK2 5.7 Hemi (Bought used in 2016 w/7k miles)
1970 Ford Mustang Boss 302 (in Family since 1974)
2013 Ford Mustang Boss 302
2011 BMW 328i
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post #6 of 12 Old 06-19-2019, 09:17 AM
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Put it neutral first, then it starts every time?

'04 Freedom Edition HO & '04 Overland HO (previous '00 Laredo 4.7)
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post #7 of 12 Old 06-19-2019, 10:58 AM
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So I made a comment <Post #5> about a Neutral Safety Switch. I just read this thread:

https://www.jeepforum.com/forum/f310...ation-4360281/

and I think it implies that the 4.7 doesn't utilize a Neutral Safety Switch. If this is so, there must be some mechanism to distinguish in what gear(s) the engine is able to crank when the key turned to start. Perhaps someone could educate me. I looked thru my 2004 SM and couldn't really figure it out. Looked like something in/near the Shift Level mechanism triggered the ability to start.

2004 Jeep Overland WJ 4.7 H.O. (Bought new in Oct 2003)
2014 Jeep Overland WK2 5.7 Hemi (Bought used in 2016 w/7k miles)
1970 Ford Mustang Boss 302 (in Family since 1974)
2013 Ford Mustang Boss 302
2011 BMW 328i
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post #8 of 12 Old 06-19-2019, 11:13 AM Thread Starter
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Quote:
Originally Posted by Double E View Post
Put it neutral first, then it starts every time?
Does the same thing whether its in park or neutral
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post #9 of 12 Old 06-19-2019, 11:17 AM Thread Starter
Madmapper
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Quote:
Originally Posted by jtpeters View Post
So I made a comment <Post #5> about a Neutral Safety Switch. I just read this thread:

https://www.jeepforum.com/forum/f310...ation-4360281/

and I think it implies that the 4.7 doesn't utilize a Neutral Safety Switch. If this is so, there must be some mechanism to distinguish in what gear(s) the engine is able to crank when the key turned to start. Perhaps someone could educate me. I looked thru my 2004 SM and couldn't really figure it out. Looked like something in/near the Shift Level mechanism triggered the ability to start.
It works off of a range selector switch inside transmission above valve body !
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post #10 of 12 Old 06-20-2019, 10:46 AM
jtpeters
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OK...got it. Copied this out of the 2004 SM.

The Transmission Range Sensor (TRS) is part of the solenoid module, which is mounted to the top of the valve body inside the transmission.
The Transmission Range Sensor (TRS) has five switch contact pins that:
- Determine shift lever position.
- Supply ground to the Starter Relay in Park and Neutral only.
- Supply +12 V to the backup lamps in Reverse only.
The TRS also has an integrated temperature sensor (thermistor) that communicates transmission temperature to the TCM and PCM.

2004 Jeep Overland WJ 4.7 H.O. (Bought new in Oct 2003)
2014 Jeep Overland WK2 5.7 Hemi (Bought used in 2016 w/7k miles)
1970 Ford Mustang Boss 302 (in Family since 1974)
2013 Ford Mustang Boss 302
2011 BMW 328i
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post #11 of 12 Old 06-20-2019, 03:11 PM
CarlJH
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check connector C100 for any corrosion, it lives right behind the headlight-under the battery tray. it has 3 wires, 1 to the starter solenoid and the other 2 are to the field winding's in the alternator.
just pull the headlight out and its right next to the cruise control diaphragm.
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post #12 of 12 Old Yesterday, 10:29 PM Thread Starter
Madmapper
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Update problem is fixed was the range selector switch above the valve body !
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