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post #1 of 3 (permalink) Old 06-13-2016, 09:25 AM Thread Starter
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Help with unusual problem

Hi All


I need some advice on an unusual problem I've had for over a year. - Truck is a 2006, 5.7 Hemi with 90k miles. I've no DTC reported and no warning lights and she is very reliable.


The issue: If I Wheel Spin (on gravel), Brake Hard so the ABS has to kick in or turn right full lock when accelerating (like turning into a right hand hairpin or my drive) then the following happens.


- The first time I use the brakes after any of the above maneuvers, the brake pedal is soft and almost goes to the floor. After the first pump of the pedal, the brakes are fine again.


I can replicate the issue anytime and at no time do any DTC's come on or any warning lights when it happens.


Brake rotors and pads are also A1


any idea's welcome - the dealer does not have a clue other than 'lets try by replacing the ABS module to see if that works' - an expensive process!


cheers


Jim
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post #2 of 3 (permalink) Old 06-14-2016, 04:18 PM
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The Key Dance or those cheap OBDII code readers only read out the Gov Mandated OBDII codes. There are hundreds, even thousands of other codes stored in the various modules on the vehicle that the manufacturers keep proprietary in an effort to force you back into the Dealerships and over pay for diagnostics and service. All the manufacturer's do this, NOT just Chrysler/Jeep.


OBDII is only what effects emissions, and just about anything going wrong with the engine will be the easy to read OBDII codes, perhaps a few transmission codes as well.


If the problem is NOT emissions, and your's sounds like it isn't, then only the dealer or a shop with an insanely expensive scan tool can read those codes that very well might be stored.


Your dealer should have used the Dealer tool to check for codes in the vehicle that you can't read. Since the manufacturer insulate the Dealerships from competition, isn't it any wonder they get worse and worse, and when customer come asking for diagnostics and troubleshooting, the dealership leaves their tools on the shelf and just start randomly guessing, replacing expensive parts on a guess?


You have the right level of brake fluid, correct? i.e. no leaks?


What does the brake fluid look like? I know the O.M. says the brake fluid lasts the life of the car, but brake fluid can easily go bad within 10 years and cause rust or gumming up in the system. Fresh brake fluid couldn't hurt. But likely if the rust or gumming up is bad enough to cause problems, fresh fluid is NOT going to fix it. Fresh Brake fluid is a preventative measure. I change it every couple of years or when the fluid gets really dark, I have never had to replace a hydraulic part of the brakes in any of my 10y.o. + vehicles for rust or gumming up internally.


You've done a visual inspection of the whole ABS system, no damaged wires to sensors or modules, etc?


Is the vehicle lifted, has oversized wheels/tires? Etc, anything that a mod could effect the suspension or the tire rpm relative to speed? Lots of people get erroneous traction control/ABS/Stability Control reactions after lifting and oversized tires. The new tire diameter can be programmed into the modules so they can do better calculations and NOT erroneously apply brakes.


If the only time the pedal is acting like a blown out master cylinder, is when the ABS activates, I also would suspect the ABS module, that opens/closes valves to release or trap pressure, or the pump that provides pressure when its needed.
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post #3 of 3 (permalink) Old 06-18-2016, 10:52 PM
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Join Date: Mar 2014
Location: NorthAmerica
Own a Commander?: Yes
Model year: 2008
Trim Package: Overland
Power-Train: 5.7L V-8 Hemi
4WD
If 4WD - system: QD-II
Current Mileage: 150000
Posts: 224
Following..............

This engine may have the hydraulic radiator fan that runs off the Power Steering pump. Check those lines as well if equipped…
Special fluid for P/S pump.

08, Commander, Overland, 5.7L HEMI, QD-II, Stock.
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