Safety Recall N23 for WH anyone had it done yet?

[Redbaron57]

After the P73 reflash I trialled 4WD-Lo every day while I was using the vehicle - no problem over 4 days. On return after 3-1/2 days away I started the engine, drove outside and tried to engage 4WD-Lo - "Service 4WD System" is back!
The US Jeep forum indicates actuator replacement does not solve the problem either.
A while back I captured the 5V supply voltage drop on engine starting by back probing the actuator terminal and connecting a recording multi-meter. The meter is pretty crude with sampling at 1/2 second intervals, but it clearly shows a significant drop. A faster recorder might reveal a lower dip. The chart below shows 2 starts a couple of minutes apart. The lower drop on the second could be the effect of the first start on the battery but it may be the timing of the sample. Sometime I will compare the drop with a well charged battery to the drop when the battery is low. Maybe a 10V 10,000uF capacitor on the 5V supply could help, provided it doesn't interfere with the 5V regulator. Any electronics guru out there care to advise?

[JamesLaugesen]

Originally Posted by Redbaron57

After the P73 reflash I trialled 4WD-Lo every day while I was using the vehicle - no problem over 4 days. On return after 3-1/2 days away I started the engine, drove outside and tried to engage 4WD-Lo - "Service 4WD System" is back!
The US Jeep forum indicates actuator replacement does not solve the problem either.
A while back I captured the 5V supply voltage drop on engine starting by back probing the actuator terminal and connecting a recording multi-meter. The meter is pretty crude with sampling at 1/2 second intervals, but it clearly shows a significant drop. A faster recorder might reveal a lower dip. The chart below shows 2 starts a couple of minutes apart. The lower drop on the second could be the effect of the first start on the battery but it may be the timing of the sample. Sometime I will compare the drop with a well charged battery to the drop when the battery is low. Maybe a 10V 10,000uF capacitor on the 5V supply could help, provided it doesn't interfere with the 5V regulator. Any electronics guru out there care to advise?

That's some cool data logging
So that's the 5V IN to the actuator sensor (not out)?
The 5V is a reference, so even when it drops to 4.7V the reference is still 4.7V.
Unless you can find somewhere else in the circuit where it doesn't drop? There may be a short somewhere (either "physical" or a fault component.) hitting the voltage after the reference is taken.
But probably expect faults from another 5V sensor in that case too.

Alternatively if the circuit has high enough resistance from corrosion or damage (if a PCB somewhere really is "cracked".), the drop to 4.7V might increase current enough to spike the resistance... dunno about that happening in ~1 second though from only a 0.3V drop.

Just a capacitor may be good enough if you match it well, but you'd still add some ripple. Since we don't know anything about the supply or rest of the circuit, would be best to use a PI filter to get a 'perfect' 5V.
But you'd need to put it as close to the 5V supply as possible, otherwise the reference voltage may be dropping... tricky since we don't know for sure where the reference is taken.

I recon adding an external 5V supply into the circuit is the best best for an experiment, as close to the supply as possible.
Then see if you still get the drop. If that smooths the drop, worst case (if there is a short somewhere in the 5V.) you might be pushing more current through something. Which you could detect by measuring current from the external supply vs the stock supply.

[Redbaron57]

After the alarm returned yesterday as per my previous post, I drove around normally. After a few more short trips today, I tried it again. 4WD-Lo worked! No alarm this time. P73 update must include a loop to check and clear the fault if the feedback voltage is back within tolerance. My hypothesis is that the voltage dip on starting yesterday triggered the alarm but after the battery recharged the problem did not recur on subsequent starts, so the fault cleared. In answer to James query in the previous post, the chart shows the variation on starting in the 5V supply at the actuator. I did not mess about to identify the feedback signal, which is obviously a lower value. I don't recall properly the feedback tolerance figures I vaguely recall reading, but I think it was a tight band around 4.7V. Given the 5V supply dropped close to that number, I expect the feedback sometimes drops out of tolerance. I also recorded the battery voltage on starting. It dropped to 10V on that occasion. The 5V regulator is not clever enough to maintain 5V when the battery voltage is that low. Instead of sitting on it's hands and leaving the alarm active the new software watches and restores control after the feedback has remained within tolerance for a while. Or perhaps I am wrong and the fault was caused by bad karma from Toyota drivers I passed and disappeared after I felt appropriate remorse.

[JamesLaugesen]

Originally Posted by Redbaron57

After the alarm returned yesterday as per my previous post, I drove around normally. After a few more short trips today, I tried it again. 4WD-Lo worked! No alarm this time. P73 update must include a loop to check and clear the fault if the feedback voltage is back within tolerance. My hypothesis is that the voltage dip on starting yesterday triggered the alarm but after the battery recharged, the problem did not recur on subsequent starts, so the fault cleared. In answer to James query in the previous post, the chart shows the variation on starting in the 5V supply at the actuator. I did not mess about to identify the feedback signal, which is obviously a lower value. I don't recall properly the feedback tolerance figures I vaguely recall reading, but I think it was a tight band around 4.7V. Given the 5V supply dropped close to that number, I expect the feedback sometimes drops out of tolerance. I also recorded the battery voltage on starting. It dropped to 10V on that occasion. The 5V regulator is not clever enough to maintain 5V when the battery voltage is that low. Instead of sitting on it's hands and leaving the alarm active the new software watches and restores control after the feedback has remained within tolerance for a while. Or perhaps I am wrong and the fault was caused by bad karma from Toyota drivers I passed and disappeared after I felt appropriate remorse.

In recon your general theory is right.
One of the fun electronic/battery-related gremlins in these jeeps haha.
I have solar panels on the roof which float an Optima Bluetop at 14.7V and haven't had any of these issues. Might just be coincidence, but I'm leaving the panels

The actuator sensor tolerance I've seen is a range of ~100Ohm (from memory.). I don't remember seeing a voltage.
The 5V supply is the reference. Comparing 5V to 5V is the same as comparing 4.7V to 4.7V (aside from a small current increase depending how the measurement is taken.).
Unless there's another stable 5V reference somewhere that doesn't drop... which would be weird.

[Redbaron57]

My thinking was influenced by an early article on the original recall that stated an absolute voltage tolerance range. If that is not the case perhaps the gremlin is caused by quick transients that I cannot capture with my crude recording meter.

[ChrisCh]

I have a 2010 WH. In 2014 had trouble with a persistent "SERVICE 4WD SYSTEM" warning. Dealer reprogrammed FDCM but said had code C1438. They the car for 7 weeks while they fixed the transfer case problem (under warranty). However soon after the "SERVICE 4WD SYSTEM" came on again. They reprogrammed the FDCM again on May 19th 2015 but soon after again "SERVICE 4WD SYSTEM". Took the car in Nov 2015 to fix a bunch of stuff under the warranty before it expired. Dealer said not enough time to look at the FDCM problem. Took it back again in Feb 2016 and was told that they had reprogrammed the FDCM (but this doesn't register on my "Mopar Owner Connect" page) but the C1438 code had reappeared and they started to tell me that the transfer case needed repairing before I reminded them that they had done this in 2014. They want the car again to check the wiring etc. Does anyone know what is actually happening here?

[JamesLaugesen]

Originally Posted by ChrisCh

I have a 2010 WH. In 2014 had trouble with a persistent "SERVICE 4WD SYSTEM" warning. Dealer reprogrammed FDCM but said had code C1438. They the car for 7 weeks while they fixed the transfer case problem (under warranty). However soon after the "SERVICE 4WD SYSTEM" came on again. They reprogrammed the FDCM again on May 19th 2015 but soon after again "SERVICE 4WD SYSTEM". Took the car in Nov 2015 to fix a bunch of stuff under the warranty before it expired. Dealer said not enough time to look at the FDCM problem. Took it back again in Feb 2016 and was told that they had reprogrammed the FDCM (but this doesn't register on my "Mopar Owner Connect" page) but the C1438 code had reappeared and they started to tell me that the transfer case needed repairing before I reminded them that they had done this in 2014. They want the car again to check the wiring etc. Does anyone know what is actually happening here?

The "N23" recall issue discussed here shows itself as code C140F ("Transfer case Range Position Sensor Erratic Performance".).

The C1438 code could be accurate (the clutch really is worn.), or could be an electrical anomaly.
Unfortunately I don't think the dealer has an obligation for this under the recall, but they may under warranty of the previous warranty works(?).

Do you have details of what they actually did when they "fixed the transfer case problem"?

An electrical issue is probably most-likely, but there is evidence that incorrect oil in the TC (like ATF.) can kill the clutch.

Pretty sure I've seen a couple of other guys mention that C1438 code, but don't remember seeing the outcome.
Hopefully they'll chime in