Archived ABS Problem!

[xxxHollywood]

My '98 2500 4x4 front wheels lock up under heavy braking. Even at slow speeds 20-30 Mph, immediate and forceful preasure makes both wheels skid. I have normal wear on all four sets pads/shoes. 92000 miles on truck, original owner. Icy conditions makes this situation disasterious. Any Ideas?

 

[Lurch]

Uh, ABS on a 98 is only rear wheels.



Lurch

 

[illflem]

You sure? My '95s both have have 4 wheel ABS.

 

[Lurch]

My mistake. I've learned it was available as an option.



Lurch

 

[Extreme1]

The only thing that comes to mind is that there may be too much assist from the hydraulic unit. Does the steering feel different?

 

[xxxHollywood]

Steering!!!!

The steering has been a little sluggish at low RPMs or in a sharp turn. Could this be related?

 

[JR2]

Hollywood

I think the brake system on your (and my) truck uses the powersteering pump for pressure so if you are having problems with the PS pump that could be part or all of the problem. I would check that out.

 

[dan_gilson]

I would be interested in knowing what you find out. My steering is slow at low RPMs too. The brakes seem a lot harder pedal at that point also.



Are the brakes grabbing? Or just not going into ABS?



If they are grabbing. Give everything a good cleaning with brake clean. I had DC over greased my front end and it got grease on the rotors. Warped one of them pretty bad. I had my local tire shop lathe on the truck for a lot less that the dealer wanted. AND they had much less wobble afterward than new rotors.



The ABS in the rear really sucks. It is just a G sensor that compares rotation with G force rather than actually wheel stoppage. The pulsation is rather slow. The fronts are much better. The brake bias is very heavy toward the rear. So, if you are lightly loaded you will not get much braking from the fronts until you get into ABS mode. This tends to give you the nothing or all feeling. You have to hold the pedal really hard to get ABS to kick in. Letting off even a little really screws up the ABS' brain.

 

[wtrenholm]

Hollywood,



I have a number of questions.



1. Do you have RWAL (rear only) or 4 wheel ABS?



2. When did the problem show up? All of a sudden, been there for ever, came on slowly?



3. How is the truck loaded when this is happening? Go to a scale and find out front and rear axle weights if the truck is not stock.



Plus make sure the rear brakes really work and are properly adjusted.



Too many variables involved to make any kind of a guess with the info you posted.



Wayne

 

[xxxHollywood]

wtrenholm



Rearwheel only Anti-lock



Came on slowly then more noticably. It seemes that RPMs has somthing to do with it.



Truck is usually empty. My trailer has brakes, hard to notice wile towing.



Break peadle feels like pushing cold Playdo though a pasta maker !!!



92,000 miles. Breaks were just rechecked, normal wear and proper adjustment.



Next step is the power steering pump... .

?



Thankyou all for your input. Any Ideas ?

 

[Ladders]

While reading the other day, a thought came to mind on some (maybe yours) of these brake/steering problems. Could be the pwrsteer fluid has moisture in it and is "freezing" in colder weather. This can make steering/braking harder due to the "ice" content. Might be worth a fluid flush/change every so many years/miles since we use the fluid for both functions. The fluid in the pwrsteer can absorb water vapor and this could plug the lines if it freezes or at least block pressure from getting thru.



Just another 0. 015$ opinion... ...



\\BF//

SOTSU!! (still around - just no time for some other things yet... ... . )

 

[dan_gilson]

Ben Stair: Thanks for stating the obvious. I always like the $3+, 20 minute solution over pulling the power steering pump any day.



It did not seem to have any effect on my issue. I even used that Valvoline synthetic power steering fluid.

 

[wtrenholm]

Hollywood



Sounds to be related to the hydro-boost (assuming the rear brakes and brake balance is correct). I guess I'd look at the fluid and system pressure for some diagnosis. I have limited experience with this system so I can't offer much more.



Wayne