Speedometer/ABS trouble
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Speedometer/ABS trouble
Hey guys,
So here's the story: I have a 1996 f150 with the standard 3.55 ls rear diff. My speedometer has been jumping all over the place, my ABS light comes on every now and again, and my brake pedal will either click or it takes a different pressure to press it down. I recently had the rear end rebuilt and I didn't notice the speedo bouncing until after it was rebuilt. We told the mechanic about it and he told us that everything was installed correctly but I still want to take it to him to double check everything. Anyways, I replaced the VSS, no difference. I unplugged the ABS module to isolate it from my truck and the speedometer was still jumping, but not as much. Could this be a possible bad ABS module? Or could it be a damaged exciter ring even tho it was just rebuilt? And if it's possibly something electrical, does anyone know any pinpoint tests I can do to isolate what the issue could be? Thanks everyone!
So here's the story: I have a 1996 f150 with the standard 3.55 ls rear diff. My speedometer has been jumping all over the place, my ABS light comes on every now and again, and my brake pedal will either click or it takes a different pressure to press it down. I recently had the rear end rebuilt and I didn't notice the speedo bouncing until after it was rebuilt. We told the mechanic about it and he told us that everything was installed correctly but I still want to take it to him to double check everything. Anyways, I replaced the VSS, no difference. I unplugged the ABS module to isolate it from my truck and the speedometer was still jumping, but not as much. Could this be a possible bad ABS module? Or could it be a damaged exciter ring even tho it was just rebuilt? And if it's possibly something electrical, does anyone know any pinpoint tests I can do to isolate what the issue could be? Thanks everyone!
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Sounds like the tone ring is not right.
To test:
Check the input from the VSS at the ABS plug with the truck on jack stands (for 4X4 all four wheels off the ground or drive while someone else is watching the voltage).
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts AC as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR
Key OFF.
Remove the harness connector from the anti-lock electronic control module.
Raise the vehicle so that all the wheels (1007) are clear of the ground. If the vehicle is a 4x4, verify the transfer case is in the 4x2 mode.
Connect a Hand-Held Automotive Meter between harness connector Pin 10 (Circuit 523-R/PK) and Pin 3 (Circuit 519 -- LG/BK).
Set the meter to the frequency counter (Hz) setting.
Gradually spin up the rear wheels.
Does the frequency increase as the rear wheel speed increases?
To test:
Check the input from the VSS at the ABS plug with the truck on jack stands (for 4X4 all four wheels off the ground or drive while someone else is watching the voltage).
Does the voltage increase smoothly and continuously from 0 to approximately 3.5 volts AC as vehicle speed increases from 0 to 48 km/h (0 to 30 mph)?
OR
Key OFF.
Remove the harness connector from the anti-lock electronic control module.
Raise the vehicle so that all the wheels (1007) are clear of the ground. If the vehicle is a 4x4, verify the transfer case is in the 4x2 mode.
Connect a Hand-Held Automotive Meter between harness connector Pin 10 (Circuit 523-R/PK) and Pin 3 (Circuit 519 -- LG/BK).
Set the meter to the frequency counter (Hz) setting.
Gradually spin up the rear wheels.
Does the frequency increase as the rear wheel speed increases?
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OLDnSLOW
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May 16, 2012 07:04 PM
