Silver Timbers

I have just bought a 2006 Cherokee I think KJ it is not starting and wasn't when I bought it.
There is no power when turning the key (no dash lights, no crank) but it tries to lock or unlock the central locking but nothing else.
I have read some online info and faults but nothing specific my thought is the ignition switch from what I gather there is an electronic switch behind the ignition and changing that seems to fix a lot of inherent problems.
I was told that this problem is common for these vehicles.
Any help is appreciated.

winley

I have the same problem with my 1997 cherokee and still seeking a solution.
Winley

Silver Timbers

What have you tested or changed

winley

I have not changed anything but the sequence of events leading up to this occurrence was as follows.
Moved vehicle normally and parked it on a slight slope - weather very damp.
When I went to move it the engine started up but stopped immediately, repeated this several times.
Towed vehicle to flat location and remote lock did not work; isolated battery and reconnected, then remote locking worked but failed to allow starter to engage.
Vehicle moved to garage for repair but not solved yet.

Comment: I have a niggling view that damp weather may be causing the electrical fault?

Noah911

The no power and no gauges activation with having a no crank/no start condition and a locks malfunction sounds a whole lot like there is a loss of overall communication occuring between systems.

The Control Area Network (CAN) of the WK Jeep Grand Cherokee is a serial data BUS communications system used for interconnecting numerous Electronic Control Modules (ECM) throughout the vehicle on a two wire multiplexed system. I am familiar with the XJ and WJ Jeeps CAN BUS operation and for a vehicles data BUS system in general. I am not very familiar with the exact data BUS of a WK Jeep though. There are certain to be differences specific to the WK Jeep model era.

There are three separate and different CAN BUS systems used.. There is the CAN-B, CAN-C, and the 'Diagnostic' CAN-C. The CAN-C is the data BUS system used exclusively to provide communications between the critical powertrain and nodes. The CAN-B is used between the body and interior nodes. The Diagnostic CAN-C (I will call it CAN-D... bc it is less confusing). The CAN-D is the central gateway or hub integral to the Front Control Module (FCM), and it physically and electrically isolates the three CAN BUS systems from each other and coordinates all of the bi-directional movement of messages being sent over the entire data BUS system. The CAN-B is more fault tolerant because it has the ability to revert itself into a single wire message relay system if a fault occurs on the overall data BUS. The CAN-C is unable to do this, and this makes it less fault tolerant.

The FCM is located on the Totally Integrated Power Module. The CAN-D is used to transmit information between the FCM/Gateway and a diagnostic scan tool connected to the industry standard 16-way Data Link Connector (DLC). While the BUS is operational, one of the BUS wires of the DLC will carry a higher voltage and it is known as the CAN-high or CAN BUS (+). The other BUS wire is carrying a lower voltage and is known as CAN-low or CAN BUS (-).

If you test the CAN BUS (+) and (-) wires at the DLC, you may find an abnormal voltage is on them.. This would be the indicator for having a loss of communication as being the reason for the issues as how they are occurring on your Jeep.

winley

Many thanks.
Winley

Noah911

If it turns out to be a data BUS communications issue; the most likely modules to be corrupted are the Overhead Console, the ABS Module, the Airbag Module, the Transmission Control Module, or the Master Door Switch.

If finding an abnormal data BUS (+) or (-) voltage, disconnecting a corrupt module should bring the voltage back to within normal specifications.. to know in this way which one it is. Fixing the electrical ground and/or power supplies of the corrupt module, or replacing a bad and faulty module is the fix for it.

winley

Thanks,
Winley

Silver Timbers

Thanks for that will check it out