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Jim Grant's Tech Tips
94
Dodge Ram Pickup, ABS Brake Job Problems
Q: I have a '94 Dodge Ram 3/4 ton pickup
that needed the pads replaced and the rotors turned. The rotors on this
truck have unit bearings in them. I took the rotors off and had the machine
shop turn them. After I installed rotors and pads I took the truck for
a test ride. When I stepped on the brakes they pulsated like I was on
ice, but I wasn't. The ABS warning light and the red brake light were
both on. The pulsating did not happen every time I stopped. Any ideas?
Thanks in advance.
A: First,
I'd recommend visually inspecting the wheel speed sensors and connections
at the front wheels. After all, you were working in that area. There is
a possibility that the wiring may have been damaged or the electrical
connections were disturbed and are not properly connected. If nothing
is found, then check the tone wheel. The tone wheel looks like a gear
or ring with teeth on it that is located just behind the brake rotor,
which can be damaged during brake service. The teeth on the tone wheel
create a signal as they pass by the speed sensor. Be on the lookout for
damaged or missing teeth or rust and debris caught on or between the teeth
on the tone wheel. Problems in this area will cause false anti-lock brake
operation and or warning lights. If these visual inspections fail to provide
an answer to your problem, you'll need to go to a repair facility. The
reason? To communicate with the anti-lock brake computer in your vehicle
requires an investment in specialized diagnostic equipment, training and
information.
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