2008 4 door, and experiencing strange happenings in the last 6 months or so...no particular pattern, just turn the key and the jeep wont crank..sounds like a week battery, but its not..I had the battery replaced and got the story about because of the Arizona heat and such, replace batteries every 2 years..the other day we're out of the jeep about 15 minutes and get back in...it wont start..its gotta be gremlins..I open the door, open the hood, tell my wife to crank it..its cranks...she tells me when it does that tap the brake a few times and it starts fine...

a week or 2 goes by and I advise a mechanic buddy...he tells this tale of if I walk around with the keys in my back jeans pocket, it builds up static electricity and the key wont be recognized by the ignition...by opening the door, tapping the break etc..it breaks the static charge and it should start...he fell short of telling me to wear tin foil under my cap..

so, before I take this story of either gremlins or the static charge to the shop and have those guys have me repeat the story as many times as possible times for their goof-customer-of-the-day pool...has anyone else experienced this..say phenomenon?

 

There is a transmission sensor that often can be the cause of this. You will find that if you turn key and it doesn't crank, with your foot on the pedal place the transmission into drive and back into park. Turn the key again, and it ought to start right up. From what I gather the sensor relays the position of the transmission to the ECU. somewhere the signal(s) get lost in translation, so to speak From time to time I experience this failure on my 07 JKU.

 

There has been several possible causes for this.Our's was the ground,adding a extended ground from the firewall to engine to starter helped with our no start problem

 

Hmm..good to know.

 

Happened with my '09 JK.. I thought it was the battery, so I replaced it with an Optima Yellow Top.. All was well for a couple weeks and it started happening again!! Brought to Jeep and OF COURSE they had absolutely no clue!! Just dealt with it every so often till I traded it in.. I just kept jiggling the key till it cranked.. Eventually it would start.

 

Great thanks...used my google-fu and found this:




NUMBER: 08-007-08 REV. A
GROUP: Electrical
DATE: July 04, 2008

SUBJECT:
No Engine Crank Or No Engine Start Due To Electronic Lockup Of The WCM / SKREEM

MODEL:
2007 - 2008 (JK) Wrangler
NOTE: This bulletin applies to vehicles built on or before May 05, 2008 (MDH 0505XX).

OVERVIEW:
This bulletin involves the replacement of the Wireless Control Module (WCM), and if equipped, the replacement of the Electric teering Column Lock (ELV). The WCM is also referred to as the Sentry Key Remote Entry Module (SKREEM).

SYMPTOM/CONDITION:
The customer will experience a no engine crank AND a no engine start condition. Also, the remote keyless entry (RKE) system will not operate. This condition may be due to an electrostatic discharge (ESD) from the ignition key into the Wireless Control Module (WCM), causing the WCM to electronically lockup. This condition may occur more frequently in dry and/or cold weather conditions where a sufficient electrostatic charge is more easily produced. This condition is corrected by the replacement of the WCM.

08-007-08 REV. A