Hey everyone after testing all my speed sensors and determining they are ok. I have come tot he conclusion that my ABS module is to blame for my strange problems...... so in a 2002 f250 with 4 wheel abs can I remove the control part of the module without having to deal with any brake fluid?? or do I need to go through the extensive bleeding process I keep hearing about

 

The Kelsey-Hayes setup has a removable solenoid/electronics unit on it.

What kind of problems are you having?

 

My problems are when I start the truck and take off the Abs light comes on only when I accelerate and the speedo starts to bounce. I replaced the rear abs speed sensor and the 2 front sensors are new as well because I just changed the wheel bearings a month ago. Also for some strange reason when the light comes on my truck starts surging. I can't tell if its the tranny engine or if the brakes are grabbing but it is doing something strange to systems other than the abs. Another strange thing is when I am sustaining a constant speed the abs light goes off and the truck runs fine but the second I push the gas it comes on and the truck chugs. I tried pulling the 60 amp fuse that runs the abs and it didn't fix it. I read the truck with a snap-on scan tool and there are no codes and all the speed sensors are reading the same speed. HELP

 

This sounds like you might have something loose in the rear end. Or a bad connection for the VSS.

The VSS (the sensor you already changed in the back) tells the PCM how/when to shift, the speedo how fast you're going, and the ABS.

If the PCM isn't getting a good signal from the VSS, the tranny will act funny.

You might have a rear-end going bad (diff carrier is moving around causing the tone-ring to move away from the VSS sensor) or the tone-ring itself is sludged up with crud.

Everything you say points right at the VSS.

I wouldn't expect the ABS unit to be doing all this, ESPECIALLY when you say it works fine until you accelerate. That leads to a bad connection or the tone-ring moving around.

I'd hate to see you change the ABS module and find out your having the same problems.

I'd open up the rear end and make sure that tone-ring is solid on the diff carrier and not sludged up with crud and/or metal bits.

 

And for the record, the VSS does go into the ABS module first, and then the ABS module sends a signal to the PCM, the speed servo (cruise control), the instrument cluster, the GEM, and the overhead console (if you have one).

 

I think the speedo is driven by a (failed, failing) separate speed sensor inside the transmission. The ABS module continuously compares all wheel speed sensor with this "roadspeed" sesnor and if the comparison is "illogical" due to a "bouncing speedo" the ABS will "fault".

According to the factory manuals the correct way, and likely the simplest way, to disable ABS is to remove the fluid level float sensor connector at the master cylinder.

"...When the (ABS) light comes on the truck starts surging.."

Or...

The truck starts surging and the ABS light comes on.

The bouncing speedo might very well be due to a slipping/grabbing clutch inside the transmission...

Constant speed, low enegine torque, no problem.

Extra torque for initial start out/up or acceleration the clutch slips/grabs, the speedo bounces and the ABS faults.

 

I don't have this problem but I just had to express how valuable this site and this moderator is. Thanks to you, krewat, and all those who help diagnose the problems
that are presented here. This reply to the poster was clear, well written and no doubt
correct. This forum gives me much needed faith in my fellow human.

 

No, it's not - it's driven by the ABS module, which uses the VSS for a speed sensor. Here's the EVTM picture for 2001:

 

Sorry, I was coming from my own experience from my 2000 E350 V10 whereas with the diff'l speed sensor disconnected the speedometer still works.

 

Oopps..even more sorry.

The diff'l sensor in your diagram is quite plainly labelled DSS, Diff'l Speed Sensor , the signal being sent to the speedo by the ABS module is labelled VSS, Vehicle Speed Sensor .

I would assume the VSS signal goes to the ABS module first (shown on another page..??) and then is passed on.

see:

https://www.ford-trucks.com/forums/7...ter-cable.html

 

Yes, the e-series uses the OSS from the tranny for the speedo.

The Superduty doesn't.

The EVTM shows it as "DSS" but it's the same thing - DSS/VSS potato/pahtato.

 

Confusion reigns..

My E350 says SuperDuty.

 

It would be wise to have the abs and pcm codes read. You will likely find a better direction to go with that info.

 

I should have told everyone all of what I knew. I pulled the rear diff cover to see if the tone ring was bad or if the rear was going out and it all looked great. Also as I said there are no codes being thrown EVEN when the abs light is on. I had it read by a snap on code reader. After reading a few more posts it really sounds like it's the PSOM. I found another post here where the guy was having the exact problem I am. The speedo isn't bouncing it's freaking out. Going from 75mph and dropping to 55 and them coming back up in an instant. Since this was brought up how do I just disable this system? I hate ABS anyway. I tried removing the 60amp ABS fuse and it didn't fix the problem. I really appreciate all the help everyone is giving me thanks alot!!

 

Pulling the brake fluir reservoir connection is supposed to disable the ABS.

But if you pulled the 60 amp fuse I cannot imagine that ANY ABS capability remained so I would start looking elsewhere.

How many miles on the tranny....??