1994 Chevy S-10 2WD Antilock Brakes Pedal to floor

DPWD23

MECHANIC
1994 CHEVROLET S-10

I have a 1994 Chevy S10 Pickup 2WD 4.3 Ltr with AC.
Problem is whenever I hit a bump when comming to a stop, the brake pedal goes to the floor and it takes a long time to stop, the ABS pump motor does NOT run. Also takes several pumps of the pedal to increase pedal pressure once again, but it still stays soft (eventually going all the way to the floor). On the antilock unit their are two aparantly adjustable valves (they look like the dump valve for an old Dodge rear ABS unit) on either side of the pump motor, and the one towards the drivers side of the vehicle is sticking out. If I push it in, it remedys the soft pedal situation until I hit another bump, when the problem recures, and the pin pops back out.

Other than replacing the entire pump unit, is their anything more that I can try to do to remedy this situation? I have bled the brakes on several occasions thinking that some air could be trapped in the rear lines (after replacing both wheel cylenders), replaced all pads, rotors, drums and shoes. The problem was happening before we replaced the wheel cylenders.
If needed I can take a picture of the unit to show the pin that is sticking out.

1 Reply

KIAORA

MEMBER
1 POST

From the description of the issue, it appears that the problem lies with the Anti-lock Braking System (ABS) hydraulic unit or modulator valve in your 1994 Chevy S10 Pickup. The sticking pin you mentioned could be the source of the soft brake pedal and the lack of ABS operation. Here are some steps you can take to address the issue:

Inspect the ABS Modulator Valve: Examine the modulator valve carefully to see if there are any visible signs of damage, corrosion, or contamination. If the pin is sticking out, it indicates a problem with the valve.

Clean and Lubricate the Modulator Valve: If the modulator valve is dirty or has debris, cleaning it and applying some appropriate lubricant might help resolve the sticking issue. Use a brake cleaner to remove any contaminants and ensure smooth movement of the pin.

Check Brake Fluid Level and Condition: Ensure that the brake fluid level is correct and that the fluid is in good condition. Contaminated or old brake fluid can lead to problems with the ABS system.

Check Brake Lines and Hoses: Inspect the brake lines and hoses for any signs of leaks or damage. A leak in the brake system can cause a soft brake pedal.

Check the Brake Master Cylinder: The brake master cylinder could also be contributing to the issue. Inspect it for any signs of leaks or malfunctions.

Scan for ABS Error Codes: Using a diagnostic scanner capable of reading ABS error codes, check for any stored trouble codes in the ABS system. This might help identify specific issues with the ABS components.