jakeepoo, my bestie on this site! i knew you would chime in. yes, unresolved. i wouldn't bother reliving all that occurred in that thread. there is the possibility that thew dealer diagnosis is correct, and only one way to find out. if wrong, perhaps i can get my diagnosis $ back! my master cylinder other than the module is good, so i could sell that for something. no interest in spending $1200 on a new unit; used seem to be in the $3-500 range. might have the same dealer service do the install, that way if they are wrong, i would have better refund leverage. we'll see.

someone on ebay responded and told me that to remove the module you remove the plastic outer casing and there are bolts with wires that you back off to detach from the master cylinder/booster assembly.

Hey there budro! Yeah!, I still got your back. I'm lost at the moment on this.. I can't remember what all was diagnosed and replaced. If I remember correctly the diagnosis was a bad skid ECU do to a voltage back feed at the stop lamp input.. I'll get back to you later this evening after I refresh my memory. Any details you have not provided go ahead and post. ✌️👽

no new details really, except the ABS light has joined the club. drivability the same.

a little backstory on the current master cylinder. this isa one family owned 4runner, but i wasn't directly involved at 111k miles when the original started making noises. the then owner sourced a replacement at a salvage yard w/85k miles on it. because of the plastic module damage, i'm thinking they told the salvage yard they need a brake booster, and the yard sold one at discount because of the damage to the module, assuming the original module would be swapped over. that never happened, and we have been driving with the cracked plastic since 111k. over time, moisture may have entered, damaging the module. so the booster is fine, but the module is not, causing electronic flakiness. that's my theory.

best option is too replace the whole unit. i could probably sell the booster side for a couple hundred to recoup some costs.

wondering if the abs control module is also interfering with my acceleration. thinking throttle body, but maybe not.....

So what would be the consequences if there were air left in the MC??

You would have a spongy and not a full brake pedal and lack full braking power.

Air compresses, brake fluid does not, so that's why the pedal would be spongy and lack a full pedal/braking power, i.e. not as much force applied to the brake pads to stop your vehicle properly.

Do you have the original first skid ECU?? Maybe it's fine. Can you please pull all DTC codes. Do this manually via DLC not with a scanner. This gives every code including ABS and VSC. I have some ideas what the issue may be but prefer to see all codes to pinpoint the problem area. Was the problem ever fixed by the dealership or mechanic?? What was done and how long until the problem came back? Or has it not been resolved at all?

It's disabled. No.

sold off the original booster several years ago. it was just gathering dust, and had an issue, so had no reason to hang onto it.

DTC/DLC: refresh my memory. any how are they manually pulled?

this concern probably first appeared over a year ago, when i was told my brake lights were always on, and by then the dash lights were also on. besides the dealer diagnostics, no work has been done.

remember, the module case is still damaged and should be replaced anyway.

i don't know if it is disable. a while back i was starting up a street hill in 2wd, and i could here the stability control kick in and the wavy car symbol briefly kicked in.

That light is always on with the abs light you said and should be if the brakes lights are constant on. So the issue is intermittent? I just read the last gigantic thread to remember. The instructions on how to pull codes manually I posted there for you already. It like a five minute procedure. When you replaced that brake plunger switch way back did you just replace that or the whole pedal assembly..?

trac light: yes, always on, but it flickered on that instance, like it was engaged.

brake lights are not 100% on. often they are on through all ignition settings, including key out. but not always. when the brake lights are on, if i slam the drivers door, they flicker. rarely, that causes them to turn off. if i slam the door again, they likely turn on.

recently noticing sometimes ignition key chime will go on when i pull the key out. need to re-insert key and pull out again to shut it off.

plunger: bought new plunger, didn't fix anything, replaced with one that was in, which i replaced at 200k after brake job, due to brake dash light on. however, tech had done poor job installing brake line causing leak, so that was why that light appeared. have not replaced any of brake assembly. did pull plunger, manually engaged it, no difference.

Gotcha, thanks for the explanation.

The instructions on how to pull codes manually I posted there for you already. It like a five minute procedure.

feeling slightly lazy, if you exactly where that post is, could you copy/paste it here and add and other instruction?

seems like a used master will run $400-$600, depending type of sale and mileage. new is $1200. i would think used should be about $300+, depending on condition etc. 50% new seems high.