Strange ABS Problem First Thing in the Morning

[TurboDiverArt]

Something strange going on. Now that it’s cold I seem to have something going on with the ABS. It didn’t happen last winter so it’s something that is new. It only occurs in the first few brake applications. I don’t know if it has to do with it being cold and then going away once something warms up. Seems that when I go to apply the brakes the ABS activates. I can hear the ABS motor engage and the pulsing sound/feel of the brake application. I’m definitely not engaging them and I’m not on anything slippery, happens with light application. I did increase the tire size by 4% but I’d think this would only decrease the application of the ABS, not increase it and not only when cold. It also happened last night when I left work, cooler night. Only seems to happen in the beginning and not with every application. Seems after the first minute or two it never happens again. I checked the brake fluid level and it’s OK. I didn’t check the power steering fluid but the steering seems fine. I had initially thought air in the line but I can’t see how this would effect it. The truck does seem to stop and braking I don’t think is affected. It’s more annoying than anything else. When it happened last night I stomped on the brakes. They seemed normal the ABS continued to be engaged but the truck stopped well.

OK, here’s a little additional information from this morning. I tried a few things. Seems only to happen when turning to the right. I have not tried it at high speeds. I do notice that it happens about every time if I’m going straight at say 10-mph, slightly turn the wheel to the right and apply a light to moderate brake, the ABS will engage. If I apply the brake first and then turn to the right it doesn’t seem to happen or happens a lot less frequently and not as noticeable if at all. I was not able to reproduce it when turning to the left. The brakes do get a little hard when reproducing the problem and turning to the right but I’m not sure if this is just the ABS pulsing. I definitely seem to have stopping power but I might not have as much, like maybe the right front is not helping to stop the car. I’m sure I have brakes because if I didn’t I would have driven onto my neighbors lawns this morning. I’ll try to reproduce it this morning when I get to work to ensure it’s really going away once warm.

I’m thinking maybe the right front speed sensor? Maybe a loose/chafed wire? If the wire were grounding/shorting (chafed wire) on the right front would the ABS system “think” the wheel was stopped? I don’t know how the sensor works and what it would read if the sensor was bad or the wire was disconnected/shorting/grounding. Neither the brake light or ABS light comes on. I did notice about a month or so ago that the ABS light came on once for about 15 seconds and then when off. I think it was in the morning but I don’t remember the above problem happening. Since the light went out and the braking seemed fine I didn’t give it another thought. My first thought when I saw the light was that the fuse had blown but then it went out.

Any ideas? Anything to check?

Art.

[Robyn]

I would definately be looking at those speed sensors.
Also if the light came on, pull up the codes on the rig. The ABS should log a code if there is something screwy going on.
The system is designed to measure speed variations from wheel to wheel and allows for small differences due to the radius of corners and such.
Personally I hate ABS
The bloody things will take away all control if you get on snow or ice and reeeeeeeeeealy need to lock the wheels.
I have the systems on our 94's shut off so they can't run.
I was going down a long grade last winter and needed to stop for a small rig stuck on the hill in the icy slush and my rig would do nothing but shake, shudder, pulse and buzz. I finally out of desperation at the last second tossed it into reverse and floored it. My burb came to a very unnerving halt inches from this little Toyota pickup and all its occupants were totally freaked out.
ABS in my oppinion is a feel warm and fuzzy item that makes people feel safe but in reality gives control to a small magic box under the dash that has about as much idea of what is really needed to stop the rig as the dead fly laying on the dash board pad.
My master computer (the one that sits on my shoulders) has a really good idea about how to make the brakes work and when to release them.
All this magic stuff sucks.
Electronic computer controled 4X4 is also on my sh@# list.
I know when I need to twist in the hubs and when to put the thing in 4X4.
I hate the electric front ends on my 94's
When the weather is cold and things can fail ( and they will when you need them most) thats when stuff don't work. Turn the key off on my 84 and it's waiting like a faithful dog to serve me when I get back, not my 94, turn the key off and the front end fall outs of gear.
I understand now that the engineers want to add a computer controlled steering overide to stop idiots from over correcting. HMMMMMMMm what happens if you really need to reef on the wheel to avoid a little kid that steps from behind a parked car into traffic??? Splat. The computer did not think you needed to be doing that with the steering wheel.

My kingdom for less electronics and more common sense.

Cut the power to the ABS and just enjoy good brakes without all the fuss.
If the ABS light comes on, HMMMM remove the bulb then it wont remind you of the troubles this stuff can be.
Best to ya
be safe
Robyn

[DA BIG ONE]

Remember, you also have frt/rear driveshaft speed sensors at the t-case if it's a NP246 which is tied into the ABS for auto 4wd operation.

[DennisG01]

Sounds just like what happened to my truck a few years ago. The place I had just bought it from said it was an "abs wheel sensor" (that's what they called it). They replaced it and all has been fine.

[redsuburban]

I have the exact same problem with the exact same symptoms except it only happens when I'm making a very low speed turn to the LEFT. It happens quite often when I'm turning into the driveway. The truck always stops and I've never had a straight line braking problem. The ABS light seems to have a mind of its own and comes on anytime it wants to regardless whether the temperature is hot or cold. The light goes off just as quick.
I've been told the wheel sensor is bad and if it is really bothersome just to pull the fuse.

[TurboDiverArt]

Interesting indeed! Went out to lunch today and the ABS light came on when I started the truck, went out in 10-seconds. I was not able to reproduce the problem but I still had some heat in the engine from the morning (it was actually warm this afternoon. Tonight when I got in it was cold. ABS light came on when started (actually never went out). It stayed on for more than a mile and at least 5-mintues. At a light I turned the truck off and re-started, light stayed off, all was good on ride home.

With 4WD it's a PITA to replace the speed sensor. I want to switch brake pads. Damn NAPA severe duties are too squeaky and dusty. Probably going back to the OEM ones (not the cheap ones).

I don't have a scan tool nor do I know anyone around me that has one. I'd love to know for sure if the codes are pointing to a speed sensor and if so which one. I

[DA BIG ONE]

[QUOTE=TurboDiverArt]Interesting indeed! Went out to lunch today and the ABS light came on when I started the truck, went out in 10-seconds. I was not able to reproduce the problem but I still had some heat in the engine from the morning (it was actually warm this afternoon. Tonight when I got in it was cold. ABS light came on when started (actually never went out). It stayed on for more than a mile and at least 5-mintues. At a light I turned the truck off and re-started, light stayed off, all was good on ride home.

With 4WD it's a PITA to replace the speed sensor. I want to switch brake pads. Damn NAPA severe duties are too squeaky and dusty. Probably going back to the OEM ones (not the cheap ones).

I don't have a scan tool nor do I know anyone around me that has one. I'd love to know for sure if the codes are pointing to a speed sensor and if so which one. I

[TurboDiverArt]

ART, I've in the past used a dremel tool w/cutting disk to slot pads from NAPA w/pretty good results.

To replace the speed sensor isn't so bad, dropping the axle shaft is the worst part IMHO; while your at it NAPA has rebuilt axle shafts w/cv joints for just over $100. USD if your are tired.

I know the NAPA ones already have a single slit down the middle. Do you cut an extra one down on either side so you have three slits? Is this to reduce dust, squeaking or prolong life? Which NAPA pads have you used? The OEM or heavy duty (severe duty). I think the heavy/severe duties are the ones they put on policy vehicles.

My ABS thing is happening more and more. When the ABS light comes on the brakes seem to work fine and don't pulse. I assume this means the ABS isn't working, hence no pulsing. When the light is out you can sometimes feel the pulsing as mentioned above. Definitely happening more often.

When I replaced my rotor I removed the speed sensor on the one side so it didn