Doctor Dave,

I believe that is the side that was replaced, right side wheel bearing. And it still would do it. Then the guy came up with the story of "replacing them in pairs".

I think insptech has a good point, "You need to check it with a scanner while operating."
I am hoping that will give a clue as to what the computer is seeing or it's response to the inputs.

My buddy emailed me with some other info.. I will post it here to see if it helps..

1. During all this, the ABS light on the dash has never come on.
2. The pump motor will start running when the truck is moving forward at 5 to 10 mph. Steering wheel can be straight or slightly turned left or
right. With the wheel turned, it will normally start the pump sooner. No foot on brake pedal required!
3. With no foot on brakes, the pump will run for an average of 5 to 12 seconds before shutting off. If you tap the brake pedal while you hear it
running, it will normally shut off within 1 or 2 more seconds.
4. I have not noticed any severe braking problems at speeds over 35 mph. The pump normallly activates on its own at speeds of 3 to 15 mph.
Slow speed smooth stops are the main problem.

My buddy is going to hit Auto Zone to find out if they can monitor or check for codes in the computer. I will let you know what he finds out..

Thanks again for all your help guys!!!
This board it great!!! I know it isnt boat related, but the truck is used for towing, so it related to some respect..

I will keep you posted.

Thanks Dick

Are we talking the low hum of the pump or are we talking the loud rattle of the ABS system activating?? Does it vibrate the pedal when you are applying the brakes??

insptech,
From what he told me, when you hear the noise (ABS motor running) if you apply the brakes, they pulse and get mushy like they should when it is working properly.. At least when I drove the truck last year, you could feel the ABS working on slow speed braking. I never did hear the motor actuate without the brakes applied. But every time the motor sounds occures the brakes will ABS so to speak.. I hope that makes sense.
Is there an actual motor that does the pulsing on this vehicle? I had a Chevy Van that had a motor mounted underneath and all the brake lines went to it. When it actuated, like trying to stop in at an intersection that was real bumpy.. it would start running and echo thru the truck body .. and of course it would ABS as I slid out into the intersection.. Got to love that ABS when it is slippery.. but any other time.. whewwww..

My feeling is that a sensor is still loose so when he moves the steering it sends info to the computer that wheel speed is different, but I would think the computer would need to see that the brake was applied before it fired up the pulsing motor?? Just a guess on my part.

checkmate454mag,
If you get a chance to send that print I would appreciate it.. did you get my email address??

Thanks again Guys.. big help

Dick

Dick;

I sent you the diagram, let me know when you get it.

There is a pump motor mounted by the fender well under the hood. It should not activate itself if the ecu sees a difference in wheel speeds and the brake is pressed. This condition that was descibed should only set a wheel speed error code. Maybe Insptech is right about the brake light switch being stuck on. You really need to scan for codes and scan all the sensors on this one. Guessing on todays cars just doesn't work. Send me any codes and sensor values you can get. Also, I don't know what kind of scanner you can get at an auto part store. You really need a quality scanner such as a GM Tech 2 or at least a Snap-On.

Vinny,
Thanks!!! I got the print. Still trying to get it to print out on one page.. But I get the jest of it. I am not sure how far my buddy will go with this on his own.. But with all this info he will be educated if he decides to take it some where.

Auto Zone in our area is offering to read computer codes for free. Not sure if they can do what we need here, but it is a start. If not I will hunt up someplace for him to get it scanned. At least he can seperate the BS from the truth..

Thanks again, I will let you know how we make out..

Thanks to everyone that chipped in!!! All suggestions are a big help..

Dick

Dick;

Anytime. Let me know if you get any more information such as codes, etc...

Vinny

Ok Vinny will do. Thanks again.

Dick

MR GADGETS I read that in our area we've had alot of problem with rust lifting the sensor off the spindle .He might want to try cleaning the mateing surface and the grease off the sensor. If he decides to give up I'd be glad to look at it at my shop for him, good luck.

As said before, the only accurate way to diag is to drive with a scan tool and watch the vehicle speed signals. I have seen on earlier truck 93-94 where the rear wheel speed signal go's out. Has there been any transmission work done lately. I had one last week where the reluctor inside the trans would move on accel, the computer would loose the rear wheel speed signal and then all hell brakes loose. I am also wondering if somthing is backfeeding into the ABS relay. I will look at a schematic at work and see what I can find.

Ok, Here is the test results so far.

1.) Scan tool was connected and looked for error codes:
None found. As suspected with no ABS light "on".

2.) with scan tool looking at wheel speed we could see that the wheel speeds did not match at the lower speeds where the problem occures.

At 3mph all wheels read the same.
At 4mph rf and rear read 4mph and lf reads 3mph
At 5mph rf and rear read 5mph and lf reads 3mph
It does this up to 7mph and then lf will catchup or equalize and read 7mph.. 8mph.. along with the other sensors.
If the wheel speed difference stays for any length of time, the ABS motor opperates and if the brakes are applied you get ABS action.

We subsituted a sensor on the left front. And yes you can get the senors seperate from the wheel bearing from after market sources.
But the exact same results occurred. Lf would read 3mph while others were gaining speed.
The left front would track at times and at other times not. So I take it this problem is somewhat intermittent. Seeing that the sensors go directly to the ABS brain. I am thinking the problem lies there.

What do you guys think?? Any one seen this type of reaction?

You guys have been a great source of knowledge and my buddy and I appreciate it.

Thanks

Dick