- Jul 22, 2014
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There have been recall issues with the transfer case (TC) used in Quadradrive II Jeeps; ie the WH/WKs (2005-10 Grand Cherokees) and XKs (Commanders), affecting the low gear range. It seems that most owners (95%?) are completely oblivious of the issue as they never use low range, and Fiat (who now own the Jeep brand) seem to have been relying on this fact; but caravanners are far more likely to use low range, and there has been a lot of anger about it on Jeep enthusiast and off-road forums.
If you try to select Low Ratio, and the message "Service 4WD" appears by the speedo, you have the problem. The TC has stayed in High Ratio.
Here is the story :-
1) There were some alleged rare occurrences of the TC actuator, of its own accord, putting the TC into neutral when parked. These was due to partial failures of certain batches of the final drive control module (FDCM) circuit board, and caused (in USA urban legends at least) some runaways of parked cars. I do not know if this could even occur with the ignition off - probably not. Nor could a runaway occur if the owner also used the handbrake and did not just rely on the "P" gearbox lock.
2) Instead of replacing all FDCMs as they should have, Fiat/Jeep "solved" the problem by a software update under Recall N23 (two years ago?). This update disabled the TC actuator, keeping the TC in high ratio mode, thus making neutral, and of course low ratio, unobtainable. In other words, the transfer case was deliberately crippled. Some owners also reported loss of the locking function of the differentials, leaving open diffs all round. If you attempt to engage Low Ratio or Neutral following the N23 update, the message "Service 4WD System" appears.
3) The vast majority of owners never use neutral or low ratio, so, as Fiat/Jeep seemed to have hoped, they never noticed how N23 had crippled their TC. The N23 recall software had no detrimental effect on fair-weather road driving. It just removed the main advantages of 4WD over 2WD.
4) The minority of owners who did notice, and complained, were told it was a co-incidence that it had happened with the N23 recall, that they needed a new actuator or even a new TC, and that they were the only person in the world who had the problem.
5) Two years later Fiat/Jeep devised a further software update (what took them so long?), and on 19 May 2015 deployed it under Recall P73. This is supposed to re-enable neutral and low ratio. P73 is a free upload now available from main dealers, apparently overwriting N23.
6) Googling for reports on the effectiveness of the P73 recall gives mixed results. Some say it has worked so far but it is still early days. It seems to have worked for me. But judging by discussions on Jeep forums, many owners are confusing the two separate recalls (ie N23 and P73) - if they are aware of the issue at all - especially if the dealer has done them at a routine service without mentioning it to the owner.
This is the text of the P73 recall :-
http://www.chrysler.com/universal/webselfservice/pdf/P73.pdf
If you try to select Low Ratio, and the message "Service 4WD" appears by the speedo, you have the problem. The TC has stayed in High Ratio.
Here is the story :-
1) There were some alleged rare occurrences of the TC actuator, of its own accord, putting the TC into neutral when parked. These was due to partial failures of certain batches of the final drive control module (FDCM) circuit board, and caused (in USA urban legends at least) some runaways of parked cars. I do not know if this could even occur with the ignition off - probably not. Nor could a runaway occur if the owner also used the handbrake and did not just rely on the "P" gearbox lock.
2) Instead of replacing all FDCMs as they should have, Fiat/Jeep "solved" the problem by a software update under Recall N23 (two years ago?). This update disabled the TC actuator, keeping the TC in high ratio mode, thus making neutral, and of course low ratio, unobtainable. In other words, the transfer case was deliberately crippled. Some owners also reported loss of the locking function of the differentials, leaving open diffs all round. If you attempt to engage Low Ratio or Neutral following the N23 update, the message "Service 4WD System" appears.
3) The vast majority of owners never use neutral or low ratio, so, as Fiat/Jeep seemed to have hoped, they never noticed how N23 had crippled their TC. The N23 recall software had no detrimental effect on fair-weather road driving. It just removed the main advantages of 4WD over 2WD.
4) The minority of owners who did notice, and complained, were told it was a co-incidence that it had happened with the N23 recall, that they needed a new actuator or even a new TC, and that they were the only person in the world who had the problem.
5) Two years later Fiat/Jeep devised a further software update (what took them so long?), and on 19 May 2015 deployed it under Recall P73. This is supposed to re-enable neutral and low ratio. P73 is a free upload now available from main dealers, apparently overwriting N23.
6) Googling for reports on the effectiveness of the P73 recall gives mixed results. Some say it has worked so far but it is still early days. It seems to have worked for me. But judging by discussions on Jeep forums, many owners are confusing the two separate recalls (ie N23 and P73) - if they are aware of the issue at all - especially if the dealer has done them at a routine service without mentioning it to the owner.
This is the text of the P73 recall :-
http://www.chrysler.com/universal/webselfservice/pdf/P73.pdf
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