ABS Gremlins in DaHooooley

[Robyn]

Been enjoying having DaHooooley back a lot.

Today after running about 50 miles I looked down to find the ABS light glowing away steadily :eek:


Checked the brakes out and they work great, in fact better than normal.

No Buzzzzzzz Whirrrrr when ya jump into the middle of them.

OOOOOOOOOOOOooook Got home later and pulled the code #68 OMG, could have been something simple like a failed wheel sensor, NOOOOOOOOO not my luck

#68 is an indicator of a locked ABS motor or a shorted circuit on that system.

From what I could tell bad connections can cause it too.

Checked with the diagnostics chart in the GM book and did some voltage and wiring checks.

Those checks all turned out fine.

Disgusted I smacked the ABS BOX real hard with the palm of my hand :mad:

Much to my delight the ABS light went out imediately. Tried restarting several times and the light goes out after the self test. :D

Possibly a bad connection but I have a feeling that I have not seen the last of this gremlin.

Nice thing is that the brake system works fine and all brakes will lock up if ya climb on them right smart.

From what I can tell from the diagnostics, this could very well point to the ABS unit and that must be serviced as a complete unit. :eek:


We shall see.

Other than this little hicup the rig has been running absolutely marvelous.

I am hoping that the fact that the truck sat all last summer, from May to August then through until a few weeks ago when I finally put plates back on it may have had something to do with this gremlin.


Plugs and connectors all look fine BUTTTTTTTTTT ya never know.


Missy

[Robyn]

Gremlin is coming and going. Brakes are fine and work perfect.\\

Tried the ABS this morning and it worked as it should, 10 minutes later the light came back on.

Good riddance. The cost to replace the unit is far more than I am willing to spend plus the PITA to bleed the system afterwards.

For now the little light can just stay on. The particular code is likely due to a circuit fault with the little motor assembly.

Seems to me that some outfit would make an adapter block that would allow the removal of the ABS unit.

The plumbing on the thing is done in such a torturous manner that to simply bypass the unit would be a real issue.

If anyone knows of any place selling such a manifold, I AM ALL EARS


Missy

[Robyn]

Gremlin in hiding today. :confused:

Must either be a bad connection or an internal problem with the ABS Unit.

Whatever the issue the brakes work well even with the light on so no biggy.


Missy

[ToddMeister]

That's what they make black tape for: cover the light! LOL

[Robyn]

If I do the light thing I will remoce the fuse from thatn system and remove both lamps.

Removing the fuse causes the red warning lamp and the orange one to both glow, Quite anoying too :eek:

As long as the thing is an on again off again issue and the brakes work properly it can remain as is.

If there comes issues with the "normal" function of the brakes then something will have to be done.

As long as the thing can't run it can't cause any trouble.

Under normal circumstances the ABS is in a passive mode and does nothing and the brake fluid simply flows through it.

BUTTTTTTTTTTT Let one of the electric valves stick open or shut ?? and all sorts of bad things can happen.

Missy

[crashz]

Robyn, have you tried bleeding the system? From a wheel cylinder (or all four)? All of my trucks seem to accumulate a lot of moisture in the brake fluid and when I bleed them (especially the 04, my DD) the fluid looks pretty grubby.

[Robyn]

I dipped out the master cyl reservoir last year and then refilled and then did the bleed out at the wheels to clean it out.

The issue I am having is a code 68 and its connected to the little ABS motor or its circuitry.

When the light comes on, a swift swat to the ABS box and then KO_KO and the light goes off and then it may stay off for quite a while.

The sad thing is that this sort of issue points the ugly finger at the ABS unit itself. Only serviceable as a complete unit.

The cost is prohibitive.

The brakes are working perfect so for now the gremlin will just have to be there.

Buying a used ABS unit and then going through the hastle of getting it all in and the system bled out again is another excercise that is likely not a great choice either.

If the brakes start having issues (Like a system failure on either end) then I will replace the unit.

This issue is called out in the GM book as "Locked motor or shorted motor circuit" "Possible poor connections"

I have checked the wiring and the connections and all are clean and sound.

If it were not for the huge hastle and having to build a bunch of stuff, I would totally remove the ABS unit and plumb the lines from the mater cyl through the combination valve and then directly to the lines feeding to the brakes.

Sadly the fittings are all different and the fittings needed are not readily available. (Probably by design)

Thoughts are whirring about machining a little manifold block that will sit right where the ABS unit sits and will allow all the lines to screw right in and work.

Finding the tools to drill and tap the ports dont seem to jump right out either.

I have done some looking online but have not found much.

The ABS unit is a fairly complex gadget with all sorts of valves, acumulators and things and it either works right or it doesn't.

As long as it in passive failure mode it is harmless and can sit there forever and not cause any issues other than an anoying light on the dash.

I have long wondered when an issue with this system would land at my feet.
Had several GM rigs with this POS and they all stayed working :(

Well now one has to give trouble.

At least its not a vital item and is nothing more than anoying.


I will continue to search for a way to eliminate the problem.

Missy

[More Power]

There's got to be a ton of these things in the salvage yards... I haven't heard of too many ABS issues through the years, so a used one might be a less expensive fix. :)

Jim

[Robyn]

Jim

Been snooping around the yards a bit and this very well may be the answer.

Called the stealer yesterday just to get a feel for what they want to fix the issue. $1000.00 parts and labor :eek:

I DONT THINK SO :mad:

There was a couple "Good used ones" on ebay in the $75 range.

Nice thing is that the same unit was used all across the lineup (pickups and Burbs


One thing I have learned is that without a power bleeder, getting the systems free of air is near impossible.

The 95 system is easier to bleed though than the earlier unit used on 92-94 trucks.

For now the rig is going to just have to do without the ABS "AAAAAAAAAAAAAAWWWWWWWWWWWWWWE" poor thing. :D

My lack of love for this ill concieved device is quite well known. BUTTTTTTT this said I dont like anoying lights on the dash reminding me that something needs fixing.

Last summer was all consumed with building DaHoooley an engine and not much else got done around here.

With poor income from the trucking business a lot of things that needed doing got put on the back burner.

This summer has got to see some much needed maintenance done on the big rig and some outside things done on the house.

$$$$$ spent on foolishness like an ABS module will have to wait for another time.

I might even entertain swapping the 95 DaHoooley off for an Older style dually 4x4 with a 6.2 and a TH400 maybe 88-91 truck.

Missy is never happy unless there is a truck deal a cookin

Right now, the big rig is a the top of the list for any and all repair $$$ that can be put forth.


Robyn

[convert2diesel]

Robyn:

One of my Buicks has had the exact problem for about three years now. My understanding of the system is that, as you said, it is a passive devise operating only when required. If the brakes are working as needed, then just pull the fuses and remove the idiot light. Problem solved.

Unlike you, I actually like the concept of a working ABS. Don't think they were ever intended to shorten the stopping distance, just give you control during the process. It is physically impossible, using the human piston method, to cycle the brakes at the same frequency as a functioning ABS system. The other advantage is that it (at least with the four circuit systems) only cycles the wheels that are locking up and ignores the ones that still have traction. Combined with good driving practises they have been a god send for me on a few occassions.

The issue I have is when they start to give problems. If you have your head wrapped around what they are supposed to do, and they don't when you need them the most, you have lost that fraction of a second reverting back to the old driving methods. I make it a point of testing them a couple times a week during the winter, just to be sure the are there when I need them.

If you want to remove the unit then spend the bucks on this:

http://www.mastercool.com/pages/flaring_tools.html

I purchased this kit a few years ago when I started rebuilding my B/D cars. Best investment I have ever made. The kit at the top does it all. Flairs, double flairs, bubble, metric, push connect (AC and Fuel) etc. You can also buy the 37 degree anvils for it to convert everything over to AN fittings. What I like about this thing is that it does it first time every time. It really works.

Bill

[crashz]

Missy,

My thought was that maybe some foreign object/water may be causing the motor to freeze up. If this was flushed out recently, then that puts that theory to bed. Its probably as clean as its gonna get.

I know these are passive systems, and I'm just thinking out loud here, but could the system ever fail and cause a "no-brake" situation? Like if a soleniod or motor would fail and close a passage off? Would it be better to pull the fuse and positively know that the internals are "parked" open with full brake pressure?

Sorry to be devils advocate here, but would rather you be safe. Also I ask, cause I can only guess as to what happens in that black box...

[Robyn]

I will be honest here (best as I can be) :rolleyes:

Most of the time the ABS is fine as it is a silent partner. This all said, the times that I have needed full control of the brakes I had to fight with the ABS instead of stopping the truck.

The concept is great, its the application that sucks.

I have been involved with big truck testing (air brake ABS systems) and was able to beat the stopping distance manually over what the ABS computer could do.

This really pissed off the promoters of the then new ABS system.


For someone who has no idea about what to do when a panic situation happens, the ABS will help keep a lid on what could become a serious problem..

The statistics show that many crashes would not have happened if the ABS had not been used.

The ABS unit, in its pulsing of the individual brakes can cause a rig to flip due to loosing braking the wrong time.

I have had far too many times that I want everything I own dragging, hell tie a rope on the back seat and throw it out, hopefully it will snag on something. (very slippery)

When this happens and all you get is BUZZZZZZZZZZZ WHIRRRRRRRRRRRR
its very unerving.

Missy grabs the shifter and slams the rig into REVERSE AND FLOOR THE THROTTLE :eek:

Tough on trannies when ya can't stop the wheels first.


Missy