Rear Locker engaged itself at 90 kph - OMG

[Toddyh]

How about this theory then:
If venting isn't happening (eg the air release valve gets stuck closed or crud is blocking the vent), then warming of the trapped air in the difflock air lines could cause the difflock to operate without the compressor being energized.

Not far off I reckon. As I said in my earlier post my breather caps were clogged with mud. Pulled them off and cleaned and issue was solved. Have since installed extended breathers in the engine bay and have not had the issue since.

[cookie9]

Not far off I reckon. As I said in my earlier post my breather caps were clogged with mud. Pulled them off and cleaned and issue was solved. Have since installed extended breathers in the engine bay and have not had the issue since.

sorry for slightly off topic Did you extend the compressor intake? I've did the diff breather but not the compressor.
After doing some decent river crossing in bendethra its got me thinking about should I do it in case i want the locker to get across a rocky creek..
thus far, I refrain from using the locker for crossings or bog holes that might drown the compressor..

[old Jack]

RDL ECU, requires 3 signals to engage;
1. Centre Diff locked.
2.RDL switch selected ON.
3. Vehicle speed below 12kph.

cheers, OJ.

[aus_andyk]

Got under and had a closer look in daylight it's actually a bracket hiding the compressor.

heres a blurry photo of the compressor the second photo shows the bracket from another angle and the connector that was full of water, the third photo shows the 2 breathers

Thanks for the photos.

As others have said, glad you're OK.

Hope the service centre can shed some light on what happened.

Cheers
Andy

[Toddyh]

sorry for slightly off topic Did you extend the compressor intake? I've did the diff breather but not the compressor.
After doing some decent river crossing in bendethra its got me thinking about should I do it in case i want the locker to get across a rocky creek..
thus far, I refrain from using the locker for crossings or bog holes that might drown the compressor..

I extended the air pump breather yeah.
If you're going to use a locker going through water my suggestion is to engage it before entry, but if that can't be avoided an extended breather is the next best solution.


OJ your wiring diagram and comments explain how the ECU activates the air pump that then locks the diff. Beyond the air pump is is still a mechanical locking mechanism. Air pressure in the line beyond the air pump would result in the rear diff locking without the air pump being activated and, therefore, without meeting those three rules.

[spot01]

I extended the air pump breather yeah.
If you're going to use a locker going through water my suggestion is to engage it before entry, but if that can't be avoided an extended breather is the next best solution.


OJ your wiring diagram and comments explain how the ECU activates the air pump that then locks the diff. Beyond the air pump is is still a mechanical locking mechanism. Air pressure in the line beyond the air pump would result in the rear diff locking without the air pump being activated and, therefore, without meeting those three rules.

But the OP said the dash lit up, so I assume it was the electronics that locked the diff? (I wouldn't think a mechanical or air pressure issue would trigger the lights?)

[rc211e]

Thanks for all the feedback and suggestions.

So I just got a call from Mitsubishi

"Sir your car is ready to go"

What was the problem I asked
"We'll explain when you get here"

Sorry please tell me what was wrong?

"The codes indicated low voltage so we reset ECU and checked everything and road tested everything operates correctly."

"Customer to monitor"

What?

......to be continued !!!

Off to pickup the vehicle in a minute. I'll pass on some of your thoughts and concerns to the Service Manager. Next step email to MMA. I'll keep you posted

Am I overreacting?

[rc211e]

But the OP said the dash lit up, so I assume it was the electronics that locked the diff? (I wouldn't think a mechanical or air pressure issue would trigger the lights?)

IMHO I think the diff tells the dash what's happening hence the lights were telling it how it was.

[rc211e]

Not far off I reckon. As I said in my earlier post my breather caps were clogged with mud. Pulled them off and cleaned and issue was solved. Have since installed extended breathers in the engine bay and have not had the issue since.

When this is resolved I will definitely extend the breathers all 3. BTB I changed the oil in both diffs yesterday and it was clean as a whistle so no water has got in but of course that doesn't mean it's not blocked I will ask dealer if he checked that. I mentioned it to him yesterday.

Also going to investigate water proofing the compressor bracket. I suspect that bracket is higher than the specified wading level.

[Kingbrown]

Diff lock detection switch reports to the ASTC ECU - as per the attached.
Challenger ABS and ASTC Schematic HBM15X03BC00ENG.pdf

I've extended both the diff breather and the air pump breather through spare bungs that are in the lowest part of the rear quarter panel space (behind the rear passenger mudflap). Route the extended lines up high in the space where the jack sits. Terminated with sintered bronze filters to keep dust out of the lines.

[spot01]

IMHO I think the diff tells the dash what's happening hence the lights were telling it how it was.

On second thoughts, I would have to agree with you, as these things are full of sensors that "report back".

[Toddyh]

On second thoughts, I would have to agree with you, as these things are full of sensors that "report back".

Looks like someone already answered your question and yeah this is how I understand it works. Basically if you plugged an external compressor in the the air line you could activate the diff lock and the dash would light up telling you it was engaged.
One of the key rules for the locker to be engaged is must be in low 4wd with centre diff locked. When mine did it I remained in 2wd high range. The 4wd lights did not flash at all.

[old Jack]

I can see the locker failing to disengage due to a blocked pneumatic line but for the locker to engage at 90kph in 2wd then the problem must be electronic!
The chances of get faulty engage signal from the RDL selector switch and then bypass the Centre diff lock safety and the 12kph safety are extremely slim!

My guess is a faulty RDL ECU, but even then if it fails then it should fail "safe" and not function. Imaging being 1/2 way around a sweeping corner at speed and the RDL engaging! That would give one a bit of a surprise.

cheers, OJ.

[Toddyh]

I can see the locker failing to disengage due to a blocked pneumatic line but for the locker to engage at 90kph in 2wd then the problem must be electronic!

I don't agree with that. Heat could create pressure which, if unable to escape, would engage the locker. When it happened to me I managed to stop and remove the breather cap (which was caked in mud). A little pssss of air, check the dash and the lights were out. Obviously this is in my particular case and the OP's case may be different. As I'm not the OP and wasn't there, I'm simply offering my opinion.

[nav27]

same thing happened to mine, again about 60k on the clock, wet roads, descending down Bells Line rd at Kurrajong.

All the same symptoms you had.

took it to the dealer, and had something (cant remember what it was right now) replaced no questions asked.