The Mitsubishi Pajero Owners Club®

[Sunnydenefarm]

Hi All,  I'm new here. And as many before me my first post is a Help post.
I have a 2003 3.2 did Pajero with gearbox problems, yes I have changed the oil ( SP III ) and the filter including draining the oil cooler.
My problem is that I have no reverse, I have read the workshop manual and checked over the wiring diagrams.
My question is:- The solenoid that engages reverse, I can hear no audible sound of it engaging, the wire which returns to the A/T ECU has system volts to it, when you engage reverse gear, the voltage momentarily drops but with in a second returns to system volts again. Is the solenoid ( No. 6 ) supposed to momentarily engage or should it remain energised for the duration of reverse gear engagement.
Should it remain engaged, if so does it sound like the A/T ECU is at fault?

Your help would be greatly appreciated.  

[Google]

[assassin]

Voltage drop is normal while it energises the solenoid and it returning shows the solenoid is energising, cannot remember specifically on these, but most vehicles solenoids remain energised while they are engaged to hold it in gear, once power is removed they disengage under spring pressure so when a different solenoid is energised it can engage without clashing with another solenoid being engaged.

[Sunnydenefarm]

Thanks Assassin for replying to me ( I have read your posts and I was hopeing that you would reply ).
Yes understood about the voltage drop, the only thing I didn't check today was if the supply voltage dropped too, which would show resistance in the supply circuit, however all the solenoids are supplied from the same source. My main problem was the duration of solenoid engagement. The workshop manual says the voltage should drop to about 3 volts on the ECU side, but it doesn't state how long, I now assume that it is for the duration of reverse being selected. Therefore the A/T ECU is letting go almost as soon as it turns on to ground the solenoid ground. It may be a faulty A/T ECU or the ECU has detected a fault and turned it off, however no DTC's are present.
Any further thoughts?

Thanks Dave

[assassin]

Swap the solenoid for one of the others, it could be that the solenoid is faulty from a partial short circuit, or it is clogged with dirt and moisture, if this works fine then you can deduce its the solenoid which is faulty and not the ECU. If it is a short circuit this can drop the ECU voltage and if it doesn't rise to a certain level the ECU will shut off the supply to protect itself.

Once you have swapped it you will know whether the solenoid is faulty or not.

[Sunnydenefarm]

Hi Assassin, you are quiet right, I had been trying to avoid doing this as I done such a nice job of putting it all back together. Well Saturday morning I shall be going under, but I will check the supply to the solenoids first.
Thanks and I shall keep this forum updated with the progress.

[Sunnydenefarm]

The Saga continues. The solenoid supply rail remains stable through all operations, so no problem there.
Removed valve body and cleaned, tested each solenoid with a bench power supply, all consume the same current, all sound the same when engergised.
Swapped location of LR solenoid with Overdrive solenoid, reassembled on to auto box ( including all the bits that fell out )( pin, o rings, gauze filter ).
Re charged with recovered and filtered oil. As the vehicle has no road tax licence, I am unable to road test, but where my workshop is, it has a few 500 yd straight sections, I twice got into limp home mode, but I currently assume that is because it is filling all the oil ways, the limp home is cured by turning off the engine for a few moments. But still no reverse, my next cousrse of action is to try and remove the A/T ECU, when I say remove I mean excavate as it appears to be buried deep in the passanger foot well.
Any removal pointers would be greatly received. I shall check the ECU for dry joints, if all appears well, it's either have it tested ( does anyone know anybody who can test the ECU off the car ) alternately E**Y a second hand unit and try substitution.
It may still be a mechanical problem in the gearbox, but I am working on least expenditure first as many of us have to nowadays.
BTW there are still no DTC's present, using the wire method ( although on the engine side I get a 51 code, EGR valve problem I believe ).

I await comments please, even if it's "give up now".

[assassin]

Remove the reverse solenoid and see if you can move the actuator manually, if not then its seized if its mechanical actuation, which I doubt it is as it is most likely hydraulic and the actuator is simply a valve to the brake band.

If it is hydraulic then it could be a problem with the supply from the priming pump; this basically works by having a small pump connected to the engine, when you start the engine one of the gearbox input shafts drives the pump to give what is called a priming pressure and this priming pressure is basically high pressure low volume oil flow to drive the hydraulic circuits which control the gearbox functions, basically they lock or engage the brake bands which drive the appropriate epicyclic gearset.

Remove the reverse solenoid and get an assistant to start the engine, hold a bucket over the hole to catch the ATF, but beware that it will be high pressure, run the engine for a couple of seconds before switching off, if you get a blast of ATF the priming pump is working, if not you have a blockage which will most likely be in the valve chest.

If it is working then suspect the brake bands for the reverse epicyclic gearset, you will need a specialist to check this, but they can be replaced. One identifier is the condition of the ATF, if it was black when you last changed it then the paper which is impregnated with ATF has disintegrated and failing and this impregnated paper is actually the brake band, and the black is the burned paper disintegrating.

It could also be a broken epicyclic gearset, it is very uncommon on these boxes so I would suggest a blockage in the valve chest or disintegrated brake band.

[Sunnydenefarm]

Hi Assassin. Thanks for your last reply.
  on our previous attempt we checked the solenoids and they were all working as they should be, we even swapped their locations, and thereby proving solenoid failure if the fault moved, alas it did not.
Before I get more involved, I have spoken to an Ex Mitsubishi main agent who said the following:- Forward and reverse should work at all times, If i were to disconnect the ECU, with a little bit of complaining from the gearbox I should be able to get reverse and forward gears, thus pointing to an electrical failure or mechanical problem. Having already performed open heart surgery on the valve body, any further into the bowels of the gearbox is beyond me and I would opt for a reconditioned or secondhand gearbox.
Something with a few less miles on the clock I think would do oaky as the present box has done 191,000 miles.
When I first got the vehicle the gearbox oil was black ( like old engine oil ) and we " pumped out " the old oil by running the engine for 60 secs or less ( as per workshop manual ). The newly replaced oil is now a light brown colour, we also replaced the filter too.

I hope to get to my workshop today and try disconnecting the A/T ecu. I shall update as soon as I get the results.

[Sunnydenefarm]

It's a sad day in our household, we are looking at a gearbox repair or replacement. The trick of disconnecting the A/T ecu worked fine, except for the fact that it wasn't the result I wanted.
This isn't the end of this saga, when we save some pennies we will get it sorted.

I do hope the trick with the A/T ecu helps others to quickly determine as wether it is an electronic or mechanical fault........Watch this space ( in a month or 2 ).

Dave

[Sunnydenefarm]

A further update on the duff A/T gearbox and a warning to others. Currently I cannot mention any names, as this matter is under discussion.
My Shogun from new was owned by a friend of mine, at all service intervals ( every 9,000 miles ) it was taken to a Mitsubishi service agent, at 54,000 miles as specified by Mitsubishi it had it's A/T oil changed, the car continued to return to the same agent throughout it's life at regular 9,000 mile intervals, the next A/T oil change should have happened at 108,000 miles, the agent omitted to change the oil, also at 162,000 miles the same agent omitted to change the A/T oil, the vehicle had 191,000 miles on the clock before it gave up. That is roughly 150,000 miles without an A/T oil change. We have all the documentation to support the lack of oil changes.

Whilst my friend is capable in many fields, vehicle servicing is not one of them, he was totally reliant on the service agent to carry out the relevant services as specified by Mitsubishi.

I suppose the moral to this story is, trust no one except yourself.

Any comments, anyone?

Last question for the moment, does anyone think that the A/T oil would be good for 150K miles, would lack of oil change cause gearbox failure?

I shall keep this post going until the vehicle is back on the road........................watch this space.

[bazza2468]

Knowing the motor trade if you took a vehicle in for a potential warranty/negligence claim they would say the lack of fluid changes at the specified intervals caused the failure, but we all know when its the other way round its not the case.

By your friend taking the vehicle to an approved agent he obviously wanted the best care for the vehicle and they have not given this, by trade i am a HGV mechanic and if people do not want certain fluids changed as per the service schedule we get a disclaimer signed as some of the modern auto gearboxes used are 5 figures to replace.

Trading standards and the CAB would offer some advice on the legal side of things but I would expect you have already been in contact with them.

I personally would also contact Mitsubishi UK explain the situation that one of their approved service agents did not carry out services as specified by the schedule, and you now have a problem with a gearbox.

All fluids will work in spec longer that their recommended change intervals but not in my view by that much.

The problem is there is no way to 100% state that the gearbox would have not failed if the fluids had been changed at the correct intervals, but the fluid will in my view have degraded so would think it could not have been working correctly.

[assassin]

Agree with Bazza on his comments.

If the fluid is brown then its a serious problem as it should be cherry red and only cherry red, particularly if it has recently been changed. This suggests brake bands as these are actually oil impregnated paper and they rely on the quality of oil to keep them impregnated and lubricated and once the oil degrades it fails to lubricate the brake bands which self destruct in a short time.

These transmissions work on a simple principle, they have a small priming pump which is connected to one of the input shafts and this runs as soon as the engine starts and its function is to provide sufficient pressure and flow to operate the control hydraulics which are contained in the valve chest, these lock the brake bands for each gear so each gear is selected, so there is another potential problem, its screwed and cannot provide either the required pressure or flow, the valve chest is degraded, worn, or the seals are shot, and all these can be attributed to a failure to change the ATF as soon as it begins to turn from cherry red to a slight brown colour, or at the manufacturers recommended intervals, whichever is sooner.

[Sunnydenefarm]

Hi guys,
   I appreciate your comments. I agree with Bazza's last line.
My friend has sought legal council, not so much for the cause & effect, but on the grounds of " Duty of care " whereas we place things in the care of others and rely on them to ( in this case ) carry out the correct service schedule as laid down by the manufacturer.
   The negligence is easy to prove in court, as we have every service invoice from new, the question we have now is how much bad publicity does the service agent want?

I just hope that anyone who reads this and pays for servicing at a dealer / agent, checks their paperwork along with their service schedule's. If we can save one person from heart ache.
Not sure if we should start a new thread, about how to avoid getting ripped off by the dealer ( or dealer.....as I spotted on an american website ), things like putting a scratch on the oil filter before taking it in for a service. Checking the oil colour before and after, there must be loads of things we can do?

Dave

[Sunnydenefarm]

The second dealer should have read dealer

[Sunnydenefarm]

Seems like we cannot use a certain word on here I will spell it phonetically "Siera Tango Echo Alpha Lima Echo Romeo"