1991 Lincoln Mark VII ABS prob- No codes- Dragging front OR

Cardiodoc,

BTDT with the corroded crimp thing on the rubber line.

If you look, I mention replacing the flexible line in the rear (common point of failure). As it was fairly cheap, and supposedly easy. It did absolutely nothing to change symptoms. Replaced a perfectly good hose!

I learned from an old Bendix Brakes instructor about opening bleeder valves when collapsing pistons. Made perfect sense! He also said to put a 2x4 under the brake pedal when bleeding brakes manually so that you don't push the seal over potentially "unused" (and severely dorked up) sections of the bore that could cause the (otherwise good) seal to hang up and develop a leak.

I had switched to Castrol LMA fluid years back due to it's low moisture absorbtion characteristics, and it get's flushed fairly regularly, or when I see it darkening. And a brake job is coming up!

This problem started after I had done the last brake job, but "well after". Ie it had been in normal use for weeks or months. Before I was told about this behavior popping up.

It was only after swapping out the control valve block last week, that the symptoms changed to the fronts. The M/C should isolate these two areas from each other. But like I said, I could find no info that was detailed enough. No blow out pictures."Parts views". Nothing!

Since the control valve replacement requires 85% of the work required to change out the entire actuator/M/C assembly, I really do not want to "get good at it". And I would like to find a way to test these things on a bench, reliably OR find a shop that can do this.

There are plenty of shops out there doing fuel injectors, there must be someone doing Teves ATE solenoids? I hope!

This one is driving me nuts.
Thanks for your reply!
Steve

Caradiodoc.

OK, searching for Teves Repair is like searching for Ford Hubcap or something inane. Or in your world, go to Google and type in FM Radio. Not terribly helpful if you are looking for a Blaupunkt FM radio from 1969. Teves was used a LOT in it's Mark IV form. Which changed a lot from this Mark II config!

I've previously searched for Teves Mark II Solenoid Repair and come up with about 380 hits, of which two or three are this thread(!), A bunch on bleeding your ABS brakes, multiple reading your ABS codes, a boatload on "watch out for that accumulator pressure, " or your accumulator is bad. Replace it, a couple from the Mark VII boards that I have been working with, a GREAT post by a guy named Duffy, who has one of the BEST descriptions of this ABS system, links to SCCOA, and links to the BMW forum where they have similar problems with their cars, but are plagued by a bad circuit board problem(which for them always throws codes!). Something that I am not. For some reason, their control unit gets corrosion in it. Not an issue in the two that I popped open! Probably because this one is mounted just above the left exhaust header!

This leaves the other 80% of the websites as foreign web-browser BS that have nothing to do with what you want at all. Or anything else. They are just out harvesting IP addresses. Or selling their search services.

You were able to find services that repaired instrument panels. And that is great, but it has nothing to do with my braking system. And no, I was not able to find a service to repair solenoid valve bodies. Had I done so, I wouldn't be here.

I have yet to try IATN or whatever, but I thought that is what I was getting here. ASE professional experience. No? (BTW Their reference to Google Groups is totally whacked. And out dated!)

I'll attempt tossing Mark IV into the mix but am not holding out much hope.

SO, I am still back to the "who and where" can I get these solenoids cleaned or serviced? OR how can I do it?

I find no websites related to this. Must be top secret! I cannot even find where to buy a solenoid.

While I thank you very much for your assistance,
my initial questions and concerns remain unaddressed.
Steve

OK! Now you're getting into the area where I am stuck! Physically and mentally!

I keep wondering about the "normal braking" flow of fluid. Which none of the books address. They jump immediately into "abs mode" and take off writing from there. So any applied brake fluid pressure should release itself back up into the system when you let off of the brakes? No valves. This appears to be the issue as it is not happening.

I love the old Ford docs, like the 67ish C6 TOPS manual. It has colored lines showing pressure, return passages, valve positioning in the valve body, for all three gears, upshifting, reverse, etc. GREAT book for learning how an automatic trans functions!

I just reread the 1967 Air Conditioning book the other night to refresh the gray matter, for another project. And it too was very detailed in it's descriptions of how things work "normally" and then went on in the troubleshooting sections to describe what happens when things get plugged up etc.

I wish I had that for this crazy Teves system!

Anyway, last night I played with the old solenoid valve control block based upon what the guys in the BMW forum were doing. I could find nothing wrong with this!

I believe the "discolored" solenoid that I found was simply a manufacturing issue with material used on the end cover. The plating oxidized or was a different color already. This was the N/C rear solenoid and after dinking around with it using a 12V source and the 7 external pins of the connector, I determined that I could find nothing wrong. Not to say that there wasn't.I just could not be certain to a 100% level! No smoking gun.

I flushed the passages with brake cleaner, activated the solenoids and flushed again. Popped the N/C units out ( can't do the N/O ones due to short leads!) And checked for garp etc found none.

They all clicked and clacked when activated, and when hit with 120PSI of air, they did their job open and closed.

So, I am stumped still.

I like your description of the operation, as it would make sense that the system should operate if the main fuse went out. This is indeed one of the pressure activated units with an electric pump and an accumulator to hold the charge.

This stuff all seems to work just fine! At least when it is in the driveway, or when I drive it! After I discharged the system and changed (only) the valve block, the pump worked fine to recharge the system and I could hear it cycle on and off with each depression of the pedal, until the air was all bled out. Then it held pressure a little longer before requiring the pump to come back on. And it would shut off in very short order. Seems good!

So, in trying to think this to death.I am wondering what in the system would cause restrictions (or leaks!) To either the front or the rear portion of the system under normal braking conditions! Presuming that what you say is true, about the control valve block being passive under normal braking. Where are restrictions (or pressure leaks?) Possible?

Again, I don't understand exactly (inside the M/C assy) how high pressure fluid is routed to the outlet passages (thru the control valve and out to the brake lines) but I will presume that it is stored in the accumulator and from there a line takes it to the master cylinder bore, and from there to the solenoid valve body. And out. Once you relax from braking, the pressure is relieved back up thru the control valve block, up into the M/C and then back into the reservoir. Once pressure is depleted enough, the pump kicks back in and pumps up that section of the system. That's my understanding.

The only other device in the lines is a proportioning valve in the rear line, but that doesn't explain the issue now, with the fronts staying on.

Does the "main" valve hold fluid pressure until you step on the pedal, causing the main piston to pass over some passage in the bore then allowing fluid to flow out?

This is where the information stops.

Where does high (accumulator) pressure get introduced into the lines. That the pressure could leak past something and stay active in the lines?

What in this scenario would explain the changing of symptoms from rear to fronts if all the rest remained the same?

If I disconnect only the ABS main fuse, and not the fluid pump fuse, to keep the "normal" pressure up in the system, could this serve as a good test of anything? Or would both fuses need to come out?

The BBA-Reman outfit looks like they deal with European Fords. Galaxy? Not here yet! KA? They don't go as far back as what this system is!

As for proprietary info.I can't agree more! These cars are packed with more bells and whistle type stuff. That surely is engineered to fail at 99K miles. A certain "tripmeter" module comes to mind in this particular car! Followed by their AM-FM Cassette premium sound units.

Thanks again for your perseverance! This is a doozy! Hopefully something simple.
Steve

Caradiodoc,

Car was MIA last nite, so no progress.

This "Lincoln" unit is a three piece, no vacuum booster affair. An adapter that bolts to the firewall (no connections to it), a booster piece (this is where the hard line from the pump/accumulator connects, and the actual M/C.

The system is of the 6 solenoid variety with 4 for the fronts (separate R & L) and two for the rear circuit which is shared.

You have pretty much said what I have found in the manuals already in: "the sequence for an ABS stop".

If I am reading you right, and applying it to my T/S process, my failure is during "non-ABS" braking, so the block, bleed, block, bleed scenario is not yet active. Ie solenoid valve activations.

What is the flow of fluid in a non-ABS stop? What "other" valves are in play.

THIS is the info that I cannot find!

My understanding is that the only other switch or valves is the one valve that determines release of high pressure fluid into the main bore, and then there is one switch that tells the pump to fill or provide more pressure to the accumulator circuit. In my case, these appear to be working. The pump pumps when it should, and pressure is being held until demanded. (Not leaking down)

I was hoping to pull the fuses last night on the car. But no car, so this still remains my plan of action.
If normal braking (as long as the accumulator has charge) produces the failure, then I must presume that the issue is in the main hydraulic unit (booster or M/C) some how. A leakage past a seal of sorts.

How the symptoms have changed from rears to fronts is still baffling, but we don't understand the flow of high pressure fluid in the M/C unit yet. There could be a common passageway that feeds the front and rear portions of the M/C (presuming that they are segregated). And one or both of the M/C seals are leaking pressure after the pedal is release. Or some check valve in the thing is not "unchecking".

I've no luck finding anyone that actually has taken one of these units apart! The units are simply replaced in whole. And either there is success or return to the wrecking yards to seek another part.

The Ford shop manual does not outline service for this unit. Replace as a whole!

Don't touch that dial!
Steve

Fuses? We don't need no steenking fuses!

No fuses. Only fusible links. Ugh.

Tore apart the EVTM tonight trying to find the "two fuses" that everyone talks about. To pull them and try this thing with no abs.

Only things I can find to disable the system other than cutting wires. Is disconnecting C135 "Antilock power relay" and C157 "Hydraulic pump motor relay".

Or the main connector to the ABS module in the trunk, and then C157 pump motor relay. Would do the same thing but it would leave power to the "Main Hydraulic Valve" which I think is the valve that releases pressurized fluid from the accumulator into the booster and M/C areas. This would allow the system to work normally, minus ABS control, until the accumulator ran out.

Sound reasonable?
Steve

Yes, I have both the EVTM and the Shop manual.

There is something called a "main check valve" and is only briefly described in the shop manual. Diagnosis is limited to a simple ohm-meter check. Pass/fail. Replace entire actuator-M/C unit! Not serviced.

In description of Actuation Assembly:
"The booster control valve is located in a parallel bore above the M/C centerline and is operated by a lever mechanism connected to the brake pedal push rod. The actuation assembly cannot be internally serviced."

Later in the Operation heading:
. The pump maintains a pressure in the accumulator ans is connected by a high pressure hose to the booster chamber portion of the hydraulic actuation assembly and a control valve. When the brakes are applied, a scissor-lever mechanism activates the control valve and a pressure, proportional to the pedal travel, enters the booster chamber portion of the hydraulic actuation assembly. This pressure is transmitted through the normally open solenoid valve through the proportioning valve to the rear brakes. The same pressure moves the booster piston against the valves in the master cylinder. This applies pressure to the front wheels through the two front, normally open solenoid valves.

This backs up what you said about the system operating in a normal mode, without activating any solenoids. Although they do not really tell you where the pressure goes when you take your foot off of the pedal.I presume it comes back up the NO solenoids and into the M/C assy.

They mention in this section "shutting off the central valves in the M/C". Here is where a nice cut-away drawing would be the best! What valves?. And this is where I get lost. No more info.

We push on the pedal, it activates a lever that then allows pressurized fluid into the booster chamber and also into the rear brake lines. More pressure on the pedal shuts these? Valves in the M/C and somehow allows pressure out to the front lines.

My guess is that I have an internal leak (or two) in the control valve section to the main M/C bore. Leaking through to one of the valves? Or something like that.

I'm off to unplug a bunch of stuff and go for a drive!

Steve

Caradiodoc,

OK, I want to change the symptom to "slow to release" rear brakes, vs dragging rear brakes which would imply that they were doing it all the time, ie stuck calipers.

I disconnected the two main relays, which shut down everything so that the system operated only on stored pressure in the accumulator. Ours must be good, because it took quite a few stops before the pedal started feeling wonky. Even at that, there apparently was enough pressure to "assist" at least the rear brakes, perhaps because the pedal travel wasn't far enough to close whatever valves the manual referred to. That feed the front brakes.

What is/was happening, is that when you depress the pedal perhaps an inch, you could feel the brakes (rears) kick in, then let off the pedal and you could see it slowly rise, still braking, until it got to a point near the resting point at which the rear brakes would let loose and travel is unimpeded until the next time you depressed the pedal. (Heavy or light braking resulted in the same action.)

Now, after dinking around doing this at slow speeds around the block, when I must have finally REALLY depleted the accumulator pressure, all of a sudden, the brakes started working normally, although totally unaided! White knuckle braking at it's best!

The pedal was hard at midpoint in travel, and hard to push from there to effect braking! The pedal would return immediately to the top position and there was no dragging of either front or rear brakes!

So, something when under pressure, even slightly, is impeding the release of the master cylinder piston or pedal, to allow it to come back up to rest position quickly. Whether this is a leak in the M/C main bore, or main hydraulic valve to M/C, or a leak from the pressure side of the booster, into the rear brake section of the M/C, I cannot say. But something is keeping pressure in a section that is impeding the travel of the pedal back to rest position after the braking action.

What I can say is that this failure appears to be in the main hydraulic portion of the M/C and it has nothing to do with the ABS computer and associated relays, pumps, etc.

Once I plugged the two relays back in, turned the key to on, the fluid pump came on and returned pressure to the accumulator in a minute or so. A couple of pedal pushes confirmed that the failure condition had returned.

If I pulled up on the pedal just after braking, I could feel the car "pop" free of the dragging brakes. I noticed that it was easier to do this when I was going around the block, discharging the pressure in the system. It is a little harder to do when it is all operating at full pressure. Perhaps a clue!

SO, I think that Friday and/or Saturday afternoon, I'll see if I can swap in another unit. And hope that it's accumulator, fluid pump, pressure switch, main hydraulic valve, and master cylinder seals are all good! What a crap shoot!

In the mean time, I have a Lucas radiator fan switch I need to see about rebuilding for my mid-engine ride. Watch out for flying small parts!

Will update when I am able to work on this car some more in earnest!

Steve

Here is a picture of the right side of this unit. If I can post two pic's I'll put the left side in here...if not, I'll put it in another post!

Pictures are always worth a pile of words!

Steve

Right view

Adapter section, booster, and M/C, pressure pump, pressure switch, and solenoid valve block.

Left view

M/C portion with main hydraulic valve portion on top bore (electrical connection at front), booster section, adapter and accumulator.

This unit came from a car with 140K on it, and compared to the one in our car, is actually pretty darned clean.....I can only hope that it was replaced!!! Could we be that lucky!??

Kind regards
Steve

The only hard line on this unit comes out of the pump body under the accumulator, goes to the other side, circles up around the reservoir and then into the "booster" section.

Yes, that thing on the far right is the solenoid valve block and the three chassis lines enter vertically from the bottom.

I had all of the factory TSB's at one time, and never came across any recalls for this. Most common problems with these units are a bad accumulator and bad relays and pumps due to the bad accumulator! (Runs the pump too much, or switches it on and off too many times. And burns the connections in the relays)

Steve

Caradiodoc,

Well, after some thrashing on Friday afternoon, and a brake bleeding session yesterday after the rain stopped, I can say that we finally nailed it!

Indeed, it was the hydraulic activator assembly (booster & M/C!) that was at fault here.

Apparently there was some sort of internal leakage in the control valve causing this odd behavior.

I replaced the entire unit, using the solenoid valve block that was original to the car. Got lucky in that the new accumulator, pump, and pressure valve all appear to be operational yet as well!

It sure would have been nice to have a stinking internal diagram of that part of the deal! As it stands, since this unit is bad, I may work on taking it apart to see "whus up" with it......why it ticks....or doesn't!

I thank you for your guidance and patience with my impatience and frustrations!!!! Just having a different piece of grey matter on it helped keep me out of the gutters and on to a win! Hope I never have to do this one again......!!! BUT, if so, now I know what to look for!!!

Cheers!
Steve

PS: Here's shot of my pet projects...where I'd rather be spending my time! Finicky, but worth it!