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Jerry, Master Mechanic
Category: Dodge
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Experience:  ASE Master tech, 30 years exp. troubleshooter, driveability tech
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ON my1997 dodge ram 1500 4x4 the 4 wheel ABS unit wont let

Customer Question

ON my1997 dodge ram 1500 4x4 the 4 wheel ABS unit wont let me bleed any where going to the rt front caliper? Iwas told that i need to have my ABS unit cycled with a scanner is this correct ? AN if so what type of scanner will do this on my 1997 rm ?
Submitted: 1 year ago.
Category: Dodge
Expert:  camerontech replied 1 year ago.

hi there,

im cam, a licenced diagnostic tech.

this system should not require a scanner to activate. as the abs unit can be manually bled. I cannot remember ever having to use a scanner for this model . also... please make sure that side caliper hose is not collapsed.

there is a bleed valve on top of the abs unit, this must be bled first.

you might have to try a vacuum bleed if its being stubborn.

i have included a diagram of the abs unit for you.

here is the factory bleed procedure. you might want to print it off:

aBS BRAKE BLEEDING

ABS brake bleeding can be performed manually, or with vacuum/pressure equipment. Refer to the vacuum and pressure bleeding information in this section.

Bleed only one brake component at a time. Recommended bleed sequence is:

  • master cylinder
  • combination valve
  • rear antilock valve
  • front antilock valve
  • left rear wheel
  • right rear wheel
  • right front wheel
  • left front wheel

Use Mopar DOT 3 brake fluid, or an equivalent meeting SAE J1703-F and DOT 3 standards, to fill and bleed the system.

Use a bleed hose at each caliper/cylinder bleed screw. Attach one end of the hose to the bleed screw and insert the opposite end in glass container partially filled with brake fluid. A glass container makes it easier to see air bubbles as they exit the bleed hose. Be sure the end of the bleed hose remains immersed in fluid. This prevents air from being drawn back into the system.

Do not allow the master cylinder to run out of fluid when bleeding the brakes. An empty cylinder will allow air to be drawn back into the system. Check fluid level frequently during bleeding operations.

Be sure to tighten each brake line fitting, or bleed screw once bleeding is completed. Loose fittings and bleed screws allow air to enter the system.

ABS MANUAL BRAKE BLEEDING

Bleed new or overhauled master cylinder on bench before installation. This shortens overall bleed time and ensures proper cylinder operation. Refer to procedure in Master Cylinder Service section.

Bleed master cylinder first, combination valve second, rear antilock valve third and front antilock valve fourth. Bleed cylinder and valves at brake line fittings one at a time. Procedure is as follows:

  1. Remove cap or caps and fill reservoir with fresh Mopar, or equivalent quality brake fluid.
  2. Loosen brake line fitting about 1-1/2 turns.
  3. Have helper press and hold brake pedal to floor. Observe condition of fluid coming out of brake line fitting.
  4. Tighten brake line fitting and have helper release brake pedal. Be sure to tighten fitting before helper releases brake pedal.
  5. Continue bleeding until fluid coming out of fitting, is clear and free of bubbles.

NEW FRONT ANTILOCK VALVE

If a new front antilock valve assembly was installed, bleed new valve as follows:

  1. Loosen bleed plug on new front valve about 1/4 to one full turn Front Antilock Valve Bleed Valve Stem & Plug Plug must be open to fully bleed upper and lower sections of front antilock valve.
  2. Remove cap from bleed valve stem Front Antilock Valve Bleed Valve Stem & Plug
  3. Install Valve Depressor Tool 6670 on bleed valve stem by sliding notched side of tool onto boss that surrounds bleed valve stem Front Antilock Valve Bleed Tool
  4. Tighten thumbscrew on bleed Tool 6670 just enough to push valve stem inward about 0.51 - 0.76 mm (0.020 - 0.030 in.) Stem must be held inward (in open position) to fully bleed upper section of new valve assembly.
  5. Apply brake pedal. Pedal will fall off significantly when bleed plug is properly open and bleed valve stem is correctly unseated (pressed inward) by tool.
  6. Stroke brake pedal rapidly 5-10 times. This action will fill upper and lower sections of valve rapidly.
  7. Bleed new valve assembly at each brake line fitting one at a time. Remember to close valve bleed plug before each brake pedal stroke. Continue bleeding until fluid flowing from fittings is clear and free of bubbles.
  8. Remove depressor tool from valve stem and install cap on stem. Then tighten bleed plug to 7-9 N·m (60-84 in. lbs.)

ORIGINAL FRONT ANTILOCK VALVE

If original assembly is being used, bleed plug and bleed valve do not have to be open during bleeding operations. Just bleed the valve assembly at each brake line fitting one at a time

Bleed first wheel brake unit. Start at left rear wheel and follow sequence recommended. Repeat bleeding operation at each wheel until fluid coming out of bleed screw is clear and free of bubbles.

Top off master cylinder reservoir fluid level. Then verify proper brake operation before moving vehicle.

Vacuum Bleeding

If vacuum bleeding equipment is being used, it is not necessary to hold the front brake metering valve open. Simply bleed the brakes following the bleed equipment manufacturers instructions.

Pressure Bleeding

If pressure bleeding equipment will be used, the front brake metering valve will have to be held open to bleed the front brakes. The valve stem is located in the forward end of the combination valve. The stem must either be pressed inward, or held outward slightly. a spring clip tool or helper is needed to hold the valve stem in position.

Follow the manufacturers instructions carefully when using pressure equipment. Do not exceed the tank manufacturers pressure recommendations. Generally, a tank pressure of 15-20 psi is more than sufficient for bleeding purposes.

Fill the bleeder tank with recommended fluid and purge air from the tank lines before bleeding.

Do pressure bleed without a proper master cylinder adapter. The wrong adapter can lead to leakage, or drawing air back into the system.

Make sure the front brake metering valve in the combination valve is held open. A spring clip tool is best for securing the valve stem in an open position.

Customer: replied 1 year ago.
I have already done everything you have listed for me to do .An i can bleed the line going in to the 4wheel ABS unit but not out going to rt side front . the other 3 wheels bleed just fine?SO my question was an still is what to do now ??
Customer: replied 1 year ago.
also my truck is 1 of the few that has front & rear ABS . someone told me i needed to have someone cycle the abs unit with a scanner
Expert:  camerontech replied 1 year ago.

to cycle the abs, one of the more advanced scanners, like a snapon or otc unit, that has access to the abs control features will be required to activate the solenoids.

if this still does not work, after activating the unit, the abs contol might be defective.