Hi,
Re: 2002 UK registered HF51JHY Grand Cherokee 2.7 CRD Limited.
I've been chasing this problem for the best part of a year without success.
Here are the details: -
Suspected PCI Bus failure.
Can be rectified, temporarily, by disconnecting and re-connecting battery negative (i), or by removing and replacing IOD fuse (F15).
On reset everything functions normally, usually for a couple of miles or so, longer if the engine is at normal temperature and/or one is driving steadily. Stopping and/or reversing can cause system drop-out.
(i) When re-setting system by this means current draw is initially around 1.2 amps, dropping to 0.19 amps after a couple of seconds and remaining steady at that reading.
Controls/displays that do not work when PCI Bus goes down: -
EVIC All fuel related displays plus time elapsed.
DOOR CONTROLS (Drivers side RHD)
Window lower and raise.(All others, mirrors/door lock are O.K.)
STEERING WHEEL CONTROLS
Radio channel change and volume. (Cruise controls O.K.)
OTHER SYMPTOM OF BUS FAILURE
Aircon indicator light sometimes comes on.
Other things that do not work: -
Auto seat position including 'easy exit'.
Light flash on lock/unlock, although locking mechanism works.
I do not know if alarm/immobiliser system is activated in "Fail state" although doors do lock using remote key fob.
When the problem first occurred, Feb 12, a look around under the bonnet revealed a cracked plastic connection on the coolant temperature sensor. Replace said sensor and all was O.K. again. Stayed O.K. until Nov 12 when it went again. Thought "I know what that is!". Purchased and fitted new sensor. Wrong! Problem still exists.
I have to think that the cause is related to changes in system when engine is running so having eliminated the coolant sensor, I thought perhaps AFM, so changed that sensor without any success. Thought about checking the EGR valve, but it didn't want to be removed after the retaining bolts had been removed so I left well (or ill?) alone. Anyway, a local garage told me it could not be anything associated with the engine.
I did have the BCM checked and was told it was O.K., even though the system was in 'fail state' at the time.
The fact that the AC light sometimes comes on when the system fails would seem to indicate that the fault is related to the IR sensor within the cab. I have had the 'head' out and there are no obvious faults. If I could find out what part number the actual sensor is I could easily replace it, rather than replace the whole head assembly. I'm not sure though, where in the U.K., apart from the main "stealership" at extortionate price, I would get one of those.
Running the self-test on the AZC system gives random results. First test after resetting it gives a "0". Second test gives "22" and "24", Left and Right blend door travel too large, and "52" AI (Recirc) door travel range too large, but I know that "52" is supposed to be a historical fault, the fault code for this, if current, being "20". I do know that the blend doors are not at fault because I have replaced them with the current aluminium models.
Would alleged faults in the AZC system send down the PCI bus?
Even the main dealers say that they could not guarantee to find the fault. What is the matter with manufacturers and their dealership networks?
As a 'BTW', I recently had the interior trim off the tailgate and, of course, a few of the clips broke. Got onto the main dealers with chapter and verse as to what I needed and was told "We can't supply you with the clips as they are not listed as a separate part.", so, says I, "What do you do if you remove the trim from a customer's tailgate and some clips break?". Answer "We would fit a new trim panel." Robbers or what?
Tony N
