Brake Failure HELP- NS

[benckj]

Truck has been going great. Just finished a cam belt change along with all the other front end components. Had vehicle on decent road trip to see my son and racked up 1000km. Wife was using it daily and then one morning she got into it to start and a loud buzzer sounded along with brake type dash lights. Starts and runs fine but no power brakes. Removed battery lead to reboot ECU and checked all fluids with no issues. What now?

I’ll try and upload some pics but running off my phone. Any help appreciated.

[KiwiNTPajero]

the brake fluid level looks pretty low???!!!

[Seigried]

Start checking all yor fuses etc. Also if your able to get it up in the air and give it a good clean and visual inspection.

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[kiwi1973]

How often have you done brake fluid flushes on this vehicle? I'm picking that, like many vehicle owners, the answer is not too often?

Open the bonnet and with a screwdriver or spanner give the metal cylinder above the brake booster a few light taps. This may get the system working again, though only temporarily. But this may help to identify the issue.

Let us know if this makes any difference. It is quite possible that the thread below is one you should be reading, as it may save you a lot of money on this repair.

https://www2.pajeroclub.com.au/forum/showthread.php?t=46516

[benckj]

Fluid is on upper limit but must admit I’ve never changed. Strange how this fault developed while vehicle was sitting couple days. We did have a fair amount of rain but nothing seems wet anywhere. I did give the booster a thump with my hand with no change to fault.

I’ll read through link above to see if any other ideas jump out. Has to be something simple. I’ve only reaching 100km on clock and it’s in very good nick.

[benckj]

That link above is magic. I understand how the system works and possible failure modes. Will check fuses, relays and tap accumulator motor to help free up. Hope I don’t have to tear down.

For anyone reading you should read the thread. A very simple fault can lead to total brake failure. Best to understand how it operates before your left stranded somewhere.

[KiwiNTPajero]

brake fluid is a regular change but very few people do it.It should be part of the regular servicing

[rykiel575]

If its like the one in the 3rd gen it means HBB has lost power. Possibly due to hbb motor pump failure. Theres an excellent thread in the gen3 section.

[Seigried]

Brake fluid is hydroscopic so it will draw moisture from the air. The more water in the fluid the worse your brakes get. This is why it needs to changed regularly.

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[benckj]

Well after understanding how the power brakes work I turned the key on and gave the relays then accumulator and finally the motor a thump with a metal bar. Motor started whirling and now I have brakes. Noticed fluid level dropped to Min point after I applied brakes several times. Had always checked before without engine running. Topped it up and took for drive.

Everything worked fine and pump motor sounds better now. Is this a warning sign that my motor on it’s way out? If so is there any way to prolong its life?

[rykiel575]

Mate i wouldnt trust it.

Only a matter of time before the brushes all fail and you lose your brakes.

You can either get it rebuilt or have a go yourself.
You can get the whole part new or get one from the wreckers or someone who is parting their pajero out which was what i did.

[benckj]

I think your right, don’t really want a suspect part on a critical system. Tell me this though can a low reservoir level (min mark) have any bearing on electric motor operation?

Just trying to figure out why a vehicle with less than 100k would have this problem. Granted it came from Tokyo and probably did more city stop and go driving than most. Never been off road before I imported it and was super clean.

[spot01]

I think your right, don’t really want a suspect part on a critical system. Tell me this though can a low reservoir level (min mark) have any bearing on electric motor operation?

Just trying to figure out why a vehicle with less than 100k would have this problem. Granted it came from Tokyo and probably did more city stop and go driving than most. Never been off road before I imported it and was super clean.

I think you have answered your own question - 50k in Tokyo traffic means the pump (& other things) has probably worked as hard as 300k in NZ. Tokyo is quite humid, so a lack of regular 2 yearly fluid changes means your fluid is probably full of water, potentially causing corrosion inside the brake system & a much lower fluid boiling point, which greatly increases the risk of brake fade when used a lot, eg, down hills (of which you have plenty in your beautiful country!).
You could try changing the fluid & bleeding the system (be careful to follow instructions for your car if DIY), although I suspect it is too late & the damage would already be done.
Brakes are one thing I would never take a chance with (family is too important) - I'd get it properly diagnosed & fixed. The whole system right through to the wheel cylinders should be checked due to the lack of fluid changes. You may also have seized caliper pistons due to corrosion which would reduce the braking efficiency.

[rykiel575]

I suspect its more the pump motor than it is the brake fluid, although it plays a part

The pump basically cycles every time the pressure reduces below tge threshold level.

There is a check you can do for hbb condition although it will wear the motor out more.

With engine off pump the brakes 30 or 40 times or until the brake pedal becomes hard and drops down a bit. Then turn key to ign and count how many seconds until the motor stops. (How long for motor to build pressure to the threshold level).
Should take 30 seconds or so.

[kiwi1973]

Benckj, the two main issues that seem to occur with these brake systems are that either the motor brushes wear out, or the pump can't pressurise due to corrosion/pitting of the cylinder walls. The first is just wear and tear over time whereas the latter can be avoided/managed with regular brake fluid flushes to keep water content in the brake fluid low.

The problem is that if you take it for repair most places will probably tell you (including Mitsubishi dealer) that the whole assembly has to be replaced at substantial cost. They may not be aware that sub components of the assembly are actually available at much cheaper prices. I've looked up some part numbers and prices for you:

MR569728 is the complete assembly and is a horrific price at $2,530.
4630A012 is the accumulator brake booster (the metal motor you gave a tap) $187.
MN102843 is the pump, brake booster and is $616.

Some people have had luck finding a good auto electrician to overhaul the brake booster at reasonable cost, but if you can buy that as a new original part for under $200 then that seems a good option (if that is the part you actually need).

All of these prices are from Partsouq and are currently in stock. Partsouq prices can be as much as half the local Mitsubishi dealer prices, and they sell parts that Mitsubishi NZ may not bring in at all. Actually I quoted the prices above in Aussie dollars, forgetting that you are actually in NZ, but close enough. I have personally purchased from Partsouq several times and they are always very efficient, dispatching from the United Arab Emirates to NZ in about 1 week door to door. I can vouch that the parts are all genuine Mitsubishi branded and packaged parts too. If you want to order from them I can send you a link to the correct part in their online parts manual so you can double check (sometimes there are alternative part numbers).