rear abs speed sensor question
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Try unplugging the ABS Module and see if the speed control and the speedometer start working right along with the transmission shifts.
Also with the ABS module unplugged see if you get the ACV (Alternating Current Voltage) to increase from 0 to about 3.5 VAC when slowly increasing speed from 0 to 30 MPH. You can do this with the rear wheels off the ground and on jack stands with the truck pointed at nothing important.
You can get at those wires at the C143 plug under the hood or on the right side of the dash.
If you have the ACV and every thing else works that I said above the change out the ABS module.
The wires are 523 R/PK and 519 LG/BK:
/
Also with the ABS module unplugged see if you get the ACV (Alternating Current Voltage) to increase from 0 to about 3.5 VAC when slowly increasing speed from 0 to 30 MPH. You can do this with the rear wheels off the ground and on jack stands with the truck pointed at nothing important.
You can get at those wires at the C143 plug under the hood or on the right side of the dash.
If you have the ACV and every thing else works that I said above the change out the ABS module.
The wires are 523 R/PK and 519 LG/BK:
/
Senior User
Joined: Dec 2009
Posts: 140
Likes: 0
From: Sydney Australia
I thought that it would be better to post here instead of making a new thread!
I have a 1990 f250 which i have changed the diff centre from a 4.1 to a 3.7.
There was a little internal protrusion which had to be ground down to give the main gear clearance.
Now ever since i had this done i have had the RABS light come on soon after start up and stay lit.
I,m wondering if the larger diamiter gears are too close to the sensor and it doesnt work correctly or is there a RABS specific gear set which has a pickup on it which the sensor detects?
If so, have i got the incorrect ones?
Any info to get it sorted would be great!
I have a 1990 f250 which i have changed the diff centre from a 4.1 to a 3.7.
There was a little internal protrusion which had to be ground down to give the main gear clearance.
Now ever since i had this done i have had the RABS light come on soon after start up and stay lit.
I,m wondering if the larger diamiter gears are too close to the sensor and it doesnt work correctly or is there a RABS specific gear set which has a pickup on it which the sensor detects?
If so, have i got the incorrect ones?
Any info to get it sorted would be great!
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
Itchy brother,
There is a tone ring gear that triggers the sensor. If you put in a ring gear without the tone ring and the ring gear is right under the sensor then yes your light will be on all the time.
Or if there is nothing under the sensor the light will be on.
And yes it would have better to start your own thread.
There is a tone ring gear that triggers the sensor. If you put in a ring gear without the tone ring and the ring gear is right under the sensor then yes your light will be on all the time.
Or if there is nothing under the sensor the light will be on.
And yes it would have better to start your own thread.
Thread Starter
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Senior User
Joined: Mar 2008
Posts: 132
Likes: 0
Subford,
Thanks a lot for the information. One thing I wanted to mention again though is that the light does not 'always' come on. Usually if it's sat for a few days, the light will not come on until I drive it for a bit then turn it off and back on. It has come on while driving, but usually it's only after I come back to the vehicle after a short stop, etc. Unfortunately, it's not common and doesn't follow a pattern of any sort that I can see.
Some other things I've been looking at are that this all started about a year ago when I had a local shop flush ALL the fluids in the vehicle and replace the rear brakes. It was fine for about 600 miles, then the light started coming on at random times.
The speedometer has always been working fine, but the cruise control has never worked since I got the vehicle.
thanks again for your help.
Thanks a lot for the information. One thing I wanted to mention again though is that the light does not 'always' come on. Usually if it's sat for a few days, the light will not come on until I drive it for a bit then turn it off and back on. It has come on while driving, but usually it's only after I come back to the vehicle after a short stop, etc. Unfortunately, it's not common and doesn't follow a pattern of any sort that I can see.
Some other things I've been looking at are that this all started about a year ago when I had a local shop flush ALL the fluids in the vehicle and replace the rear brakes. It was fine for about 600 miles, then the light started coming on at random times.
The speedometer has always been working fine, but the cruise control has never worked since I got the vehicle.
thanks again for your help.
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