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Discussion Starter #1
Just bought a Verde that was supposed to be solid but needs a lot of work.

In testing the ABS I found that I get a really stiff pedal under hard braking that then abruptly goes to the floor and locks the front brakes, and maybe the rears also - very scary. At the same time all the lights on the ARC came on along with the low fuel, high temperature and low oil pressure lights. Now the ARC doesn't seem to work at all, except that the seatbelt light comes on at start.

Regarding the ARC, is there a fuse or something that would have caused it to go dark? I had a non-ABS Milano that had a wonky ARC that I just unplugged, so do I really need it on this Verde?

For the ABS, it appears the pump is working. I can hear it run briefly at startup, and when I bled the rear calipers it would run when I had the bleed screws open. I'm assuming the problem is the accumulator, but want to check the ABS fuses but can only find the one near the battery, which looks to be OK. I can't find the other three fuses and the relays that are supposed to be under the dash, does anyone have a picture or suggestions how to find them.

Any help is appreciated.
 

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The ARC in these Milanos are ok most of the time, but the power to them has to be better than the stock supply, thus the modification of adding a better power chip. That works ok.

The other thing is that the wiring connection plugs have to be clean and protected with a dielectric so that they are consistent in their connectivity. For instance, ours doesn't like cold temperatures, so that when I start the cold car on a very cold day,near or lower than freezing, the display will once in a while not come on at all until I turn the key off and back on. Then it seems to work just fine from then on through the drive. Maybe this problem is something inside the module, but all I know is that this doesn't happen with warmer weather.

We don't worry about it. In fact, my wife just says "stupid thing, who needs it, I pay no attention to it", lol. True that.
 

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If it is working some of the time then it is unlikely to be a fuse. It is a few years since I sold my Verde but I was a bit of an expert on ABS when I sold it.
Hard pedal is low hydraulic pressure. My pump used to quit when it got hot and I fabricated a heat shield to keep it cooler.
I think that the accumulator test is how many times can you pump the brakes before the pump kicks in. Lots of pumps = good accumulator.
Going suddenly from poor brakes to good brakes probably means something that was holding out the pump decided to let it run. The pressure switch can do that. Worst case your pump is on its last legs.
My car had an in line fuse for power to the ABS computer hidden in the wiring harness behind the dash close to the driver side door.
 

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Those fuses are up behind the normal fuse box, like if you were adding an aftermarket car stereo. All ours looked good but one was cracked. I would go ahead and replace them all just to be safe.

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Wow, just typed a long response, which was lost in cyberland. Frustrating. Thanks AlfaBB.

Oh well, let's try again . . .

To supplement the advice given so far, the ABS relays/fuses are indeed behind the fuse box. What is often not stated here on the BB is that the fuse panel can be swiveled forward after a Phillips screw is removed(top middle). Once forward the panel can be lifted slightly to free the two opposing horizontal posts from their respective holds. Then the panel can be moved several inches forward to gain easy access to the wiring behind the panel. This is obvious to most but not to some of us. Me anyway.

Another point not often stated is the location of the ABS ECU. It is mounted in the trunk on a vertical panel just inside the driver side quarter panel. Some trunk fixins need to be pulled back(carpet, etc.).

When you stated the the pedal 'goes to the floor', did you mean that literally? Or did you mean that suddenly the power assist came on, the same pedal force instantaneously caused the brakes to lock? If the pedal actually went to the floor, that sounds more like a master cylinder problem. Perhaps you have multiple issues.

AFAIK, a bad accumulator will cause the pump to run frequently or continuously.
AFAIK, the ARC should not affect the ABS ECU. I believe some reporting back to the ARC is done, but the ARC should not affect the functioning of the ECU.

FYI I recently had no power assist. The problem was the pressure switch was bad and not energizing the pump. Not wanting to spend $200-$300, a Delco substitute(Delco 25530882) was found. This appears to be an identical replacement.

There are three sources of information I would recommend; Group 22 and Group 43 from the 75 manual, and the ABS Mark II Braking System manual. These can be found on-line. If you have trouble finding them, shoot me your email via PM.

Good luck.
 

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Discussion Starter #6
Thanks to everyone for the help.

Dragline, thanks for the tip regarding removing the fuse box. Even with the fuse box out of the way it is difficult to find the fuses and relays. I expected them to be mounted together but the fuses are separate and I could only find the 30A fuses. I'll continue looking after my hands thaw out.
I have an old International Auto Parts June 1986 Milano workshop manual with Group 22 only covering the ABS brakes, not the traditional ones. That's good for my purposes unless I get totally frustrated and decide to get rid of ABS.
I have been afraid to drive the car over about 30 MPH, but have found that for mild braking there is no problem. However for any sort of emergency braking the pedal gets very stiff and even kicks back a bit without providing any serious stopping power. Then suddenly the pedal goes down, not to the floor, and the brakes lock up. There is no way to modulate the brakes, they are either marginally effective or locked up.
Based on your experience and similar advice from Alfaparticle I may try replacing the pressure switch. I'm trying to locate an accumulator as a last resort. I've been told that one from a Jag XJ6 may be a good replacement and probably the only one still available, but they start at about $300.
 

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See picture of four relays and three fuses. Yes, they are all mounted together but should be pretty easy to access once the fuse panel is released and moved forward of the dash. You have enough Alfas and have been around long enough that it doesn't need to be said, but for other's sake, disconnect the battery to avoid a possible catastrophe.

Based on your description, it doesn't sound like the pressure switch, but what do I know. Nada. The ABS manual has a flow chart for diagnostics. You might want to follow that first before investing some cash. I used it to isolate the pressure switch in my case.

If the pressure switch, pump, and accumulator are good, you should hear the pump run for a second or two once the key is turned(before engaging the starter motor). If the accumulator is bad, the pump will run, almost continuously. Mark_toro replaced his accumulator with a new Mitsubishi unit although he had to have the fitting machined to do so. Not sure he would do it again. Here is his post on the subject.
 

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Discussion Starter #8
I found the fuses and they all test good. Didn't test the relays, can't get my hands in to get them loose, and not sure how to test anyway.
The pump runs for a couple of seconds when I turn the key to run position. Also runs for a second or so when I press on the brake pedal, also with the key in run position but not running - the exhaust is so loud I can't hear anything with it running. Based on your observations it seems like the pump, switch and accumulator are probably good, although the pump may be suspect. Although the pedal doesn't exhibit the standard master cylinder problem - it doesn't go smoothly down - I'm wondering if it could be a master cylinder problem nonetheless.
I've not tried the diagnostic flow chart because it requires pressure testing in the first few steps and I can't find a pressure gauge with the banjo fitting like the Alfa tool. I may just pretend I took those steps and go on farther in the chart.
It's hard to get much work done because of the weather, but I'll follow up as I am able to test more.
Thanks for your help.
 

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. . . The pump runs for a couple of seconds when I turn the key to run position. . . .
This is normal and expected.

. . . Also runs for a second or so when I press on the brake pedal . . .
On each and every pedal depression? That's definitely not right. When I earlier mentioned running continuously, I didn't mean that literally, but running often. ie every pedal depression.

From the ABS MarkII manual;

" . . the accumulator is divided into two sections separated by an elastic diaphragm; one section is preloaded with gas at a pressure of 80bar, the other at the pressure of the brake fluid. . . ."

and

" . . The electric pump makes it possible to bring the brake fluid pressure (in?) the accumulator to a value of 180 bar. This pressure, at such a high value, is essential for the achievement of rapid response during ABS control. When the pressure in the accumulator goes below 140 bar, the pump is automatically enabled. . . "

alfaparticle said:
. . . I think that the accumulator test is how many times can you pump the brakes before the pump kicks in. Lots of pumps = good accumulator. . . .
Possibly many failures will show your symptoms;
-pump is weak and cannot achieve the 180 bar
-pressure switch hysteresis is faulty (on/off something less than 140bar/180bar)
but most probable
-accumulator diaphragm is ruptured, not allowing it to store energy/pressure

Another anecdote;
Without power assist (pump not running), the braking action was limited but still retained an nice linear feel. No herky-jerky type of behavior. Not the safest way to drive, but allowing for extra stopping distance, it seemed mostly normal in feel and operation.

What you describe is much different. I would recommend as a test you find a safe place to try and run the system without any power assist to see if the same brake-locking results, or if braking is more normal. You might accomplish this by disconnection the connector at the front of the power switch.

If you are still not able to modulate braking, I would suspect the master cylinder as well.

And here in lies the rub . . . for all of us still running ABS. How long can the original master cylinder be expected to last? Time permitting, I'll search for possible rebuilding resources. Maybe someone will chime in.
 

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Discussion Starter #10
That's very good information, reducing a lot of information down to just what's important, at least for my situation. I had read Alfaparticle's post but that piece got lost in the clutter in my head.
I disconnected the plug to the pressure switch and tested both with the key run position both before and after starting. The pedal feels like that in my non-boosted Duetto, firm but linear and solid. It's raining right now, but will go for a short drive where I can safely test when it dries out.
In the meantime I'm looking for a pressure tester to check the accumulator, or else an accumulator.
At least I'm feeling more confident that I won't need to do all the work to replace the whole system with non-ABS.
Thanks.
 

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Couple of things -
If the pump runs with every brake application - then the accumulator is bad. It should run at start up after sitting overnight, and then should allow for 25 pedal pushes before it runs again. Good check is to turn the key to on, allow the pump to run and then stop (full pressurization). then turn the key off. 20 -25 pumps before the pedal becomes rock hard (you will know the sudden difference). If it passes that test then the accumulator is fine.

In the cold my ABS provides weird "kickback to the pedal". Firm application seems to be OK, but feathering the pedal causes a kickback before braking resumes. I suspect this is in the master cylinder. I've run a full diagnostic on the system with the Alfa tools and only find faults for the wheel sensors and the M/C shuttle valves.

Your description of the pedal action sounds similar except for the "very stiff" and "locking up". Issue may reside in the M/C, and fortunately those seem to be reasonably available.

Don't forget about normal brake refresh stuff - new flexible lines (I like the stainless braided fro a few $ more) and a good bleed (sounds like you already have done the rears).
 

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Discussion Starter #12
Mark_toro
I tried the test to check the accumulator. Pumped 40 times because if a little is good a lot is better. No change in pedal feel. I think with help from a lot of people I'm confident that the accumulator is the problem, or at least the main problem. Now all I need to do is find a good accumulator.
I'm still going to test with the pump disconnected to see if there may also be a problem with the M/C.
I'll keep posting my progress until the problem is resolved or I give up.
Thanks.
 

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. . . and fortunately those seem to be reasonably available. . . .
New? Rebuilt? Or just used? There is a used one on eBay now, offered for something like $300. This is ridiculous for a used unit in unknown condition, a unit unlikely to be in great condition after so many years. One here on the BB recently went for $120, purportedly in good condition but again, for how long at these ages? The ABS MC is much more complicated than the average non-ABS unit. If NOS was available or rebuilding service was known . . . .

Your post on the Mitsubishi accumulator is linked below in post #7. Have you posted the part number of that unit previous? Couldn't find it. Or is that a path you would no longer recommend?

Thanks.
 

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. . .Have you posted the part number of that unit previous? . . .
Never mind. Found it in your Mitsubishi thread;

. . . There are Mitsubishi spheres 4630a011 that maybe will work, but I haven't had one in my hands yet (ordered one from e-bay for $112). . . .
However the question, "Would you go the Mitsubishi route again" is still of interest.
 

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I would recommend the Mitsu accumulator. Mine has been serviceable for three years as a daily driver. (60K miles) However, I would go a different path for attaching it. Last time I had a local machine shop re-thread the accumulator fitting. Next time, I would have them fabricate an adapter that the Mitsu screwed into directly and then would screw into the pump. This would allow future replacement w/o the help of the machine shop.

The fitting on the Mitsu accumulator was not easy for them to machine. Kind of gummy crappy steel.

True - ABS M/C are available used only, but not too expensive. I have a spare that I picked up for around $100. I haven't torn into it yet to see how difficult they would be to recondition. But given availability of pumps, accumulators, wheel sensors - the M/C is much better.
 

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Discussion Starter #16
Drove the car today with ABS pump disconnected. Brakes were consistent with no pushback or dropping to the floor, but pretty much unusable - no matter the pedal pressure they barely worked. I think the M/C is ok.
I think I'm going to go the Mitsubishi accumulator route. I should be able to machine an adapter fairly easily. My only concern is the additional height, it looks like the existing accumulator is pretty close to the hood. Maybe a 90 degree adapter? Or a unique power (brake) bubble in the hood!
 

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Or move the pump mount down some. Haven't laid it out yet, but I think your path is doable.

Let us know how it goes with the adapter.
 

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Discussion Starter #19
Thanks.
I've already ordered the Mitsubishi Accumulator. Should have it Saturday and hope to be able to machine the adapter next week. Checked with eurospare anyway and they don't appear to have them anymore.
My ARC problem isn't that I get the Christmas lights, it's that none come on at all except the seatbelt light. I've checked that all of the connectors in the back of the ARC are clean and fully plugged in, so not sure what's happening and can't find anything in the workshop manual for that situation.
 

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Thanks.
I've already ordered the Mitsubishi Accumulator. Should have it Saturday and hope to be able to machine the adapter next week. Checked with eurospare anyway and they don't appear to have them anymore.
My ARC problem isn't that I get the Christmas lights, it's that none come on at all except the seatbelt light. I've checked that all of the connectors in the back of the ARC are clean and fully plugged in, so not sure what's happening and can't find anything in the workshop manual for that situation.
I have a spare ARC, I believe it works. But might be handy for a rebuild if you want to then swap them out. If you're interested I'd sell it for $20 plus shipping.

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