rebuilt brakes, ABS howl and pull to the left when braking

[M.D. Farragher]

I recently rebuilt the brakes on my 1995 Ex XLT. New pads in the rear, new extended flex lines, calipers, rotors, and pads in the front, and one new ABS sensor on passenger side. Also replaced the rigid passenger side line in the front as I discovered the fitting was stripped. Bled the crap out of them and have a nice firm pedal. Not everything got replaced at the same time. First the pads all around, then the front flex lines, then the ABS sensor. When I took the vehicle out for a test run the ABS howled and it pulled to the left. I figured I hadn't bled them enough so I did it again. Same hard pedal. Same result. Replaced the calipers and rotors because I was going to do it anyway with 175K on them, and now was as good a time as any. Bled it again, got same firm pedal, and same, ABS howl, and pull to the left. In the meantime I had replaced the rigid line on the passenger side, and wound up with the same result. Pulled the two 30AMP fuses in the relay panel for the ABS, and howl goes away, and vehicle brakes dead true. I should add that there are no ABS lights on dash when the fuses are in place and it is performing badly.

Any ideas or input? ABS module? ABS pump? Can either be tested?

 

[drdoom]

Is there any possibility that air got into the ABS pump? Because if so, I believe it has to be bled with a scan tool. Regular bleeding won't work. I'm not sure but just wanted to throw that in.

 

[C420sailor]

That was my thought too. Forscan will do the ABS module bleed.

I think you can see ABS sensor live data too...but don’t quote me. Wonder if you’ve got a bad sensor...

 

[J_C]

While it seems possible that you have air in the lines and too few wheels have enough brake friction to stop the vehicle, in that case you (or someone off to the side watching) should observe a wheel locking up when ABS comes on, and it would continue to lock up when the ABS fuse is pulled.

If no wheels are locking up, and pulling the fuse made a difference, it seems more likely that you aren't getting a reading from one of the ABS sensors. The signal from them gets weaker when going slow.

I'd use an OBD2 scan tool capable of live data to watch the speed sensor data while stopping. Unless my physics are off today, seems like pulling to the left (perspective from driver's seat) means it is the passenger front that the ABS is activating to not provide stopping power so would be the passenger side sensor or connection between it and the computer that's the fault... unless your wheel reluctor/tone ring is terribly corroded (exterior ring with RWD) or interior (to hub, on 4WD vehicles) ring is contaminated with metal particles stuck in the grease because the bearing is going out.

Why was the front passenger sensor, and only(?) that sensor replaced? You might measure the resistance of the sensor and inspect the connector for corrosion. I measured my original at 420 ohms and an aftermarket was 440 ohms.

 

[M.D. Farragher]

Let me clarify. First off, the car stops whether I have the fuses in or out. Fuses in, it has a firm pedal at first, but when brakes are applied, ABS comes into play, pedal gets funky, pulsey, and eventually pulls to left, but stops. This tells me the right front circuit is not getting pressure.

When the fuses are out(no ABS electronics in play) the vehicle stops perfectly, hard pedal, straight as an arrow, and on a dime.

Why did only one sensor get replaced? Well, I am coming in behind work that was badly done by hired service. And lo and behold, they severed the ABS sensor cable on the passenger side and had to replace it. In so doing, they put the wrong one on. So wrong it was loose in the hole. Why do people do things like that. I discovered it, replaced it with one I had around. It was good enough to clear the ABS light on the dash. I thought it was a good one. Also, hubs are new within 1,000 miles. It has a whole new front end under it, wheel to wheel. Re-geared as well for larger tires.

I ordered a new wheel sensor. Be here Friday. Let you know what happens. Thanks for the help.

 

[CDW6212R]

That sounds like air in the ABS module. If the ABS is disabled, then the fluid bypasses around the internal passages. That would explain why it brakes differently each way.

I'd get the needed tool quickly and figure out how to force the ABS to "operate" while bleeding the brakes again. Please post anything about how Forscan can do that, that would be a valuable function for most people.

 

[J_C]

I still think it seems more like the sensor signal dropping out of a detectable range, but if there were air preventing the circuit to one of the wheels from generating enough pressure, that wheel would be less likely to lockup, less likely to cause ABS to activate, unless the opposite-side front wheel couldn't maintain traction. This is where getting the live scan tool data comes in, or just shotgunning it with a new sensor.

I am doubting that our generation of vehicles supports the ABS bleed using Forscan. That feature seems to appear in the forscan menu when reading a newer vehicle with HS-CAN, and of course if the scan tool dongle supports HS-CAN, while 2nd gen Explorers don't do CAN at all. It seems that even among vehicles that do HS-CAN, forscan may not support this feature for all of them.

 

[M.D. Farragher]

Well, they are inexpensive enough that I ordered one. I'll get both the sensor and the tool, which may be helpful for other things down the road, since I am building this for the longer term. Will have both on Friday thanks to Amazon. I'll try the sensor first, then if that doesn't solve the problem, I'll see if the scan tool helps. Nothing I read says the the pump circuit is isolated meaning able to trap air, thus requiring a separate bleeding procedure, but something is definitely wrong. The one thing that bugs me is having had an abs light on for a bad sensor previously, but not having a performance issue, then replacing a sensor, having no lights, and having a performance issue. Are ABS units sophisticated enough to have solenoid valves in them to isolate the pump circuits from the rest of the braking circuit to create the fail safe when you pull the fuses or they don't have power to them, or they themselves fail? And if so, would they not power up when the key was turned on?

 

[C420sailor]

Haven’t tried it yet, but ABS bleed is an option when I connect my Ex to Forscan

 

[CDW6212R]

Well, they are inexpensive enough that I ordered one. I'll get both the sensor and the tool, which may be helpful for other things down the road, since I am building this for the longer term. Will have both on Friday thanks to Amazon. I'll try the sensor first, then if that doesn't solve the problem, I'll see if the scan tool helps. Nothing I read says the the pump circuit is isolated meaning able to trap air, thus requiring a separate bleeding procedure, but something is definitely wrong. The one thing that bugs me is having had an abs light on for a bad sensor previously, but not having a performance issue, then replacing a sensor, having no lights, and having a performance issue. Are ABS units sophisticated enough to have solenoid valves in them to isolate the pump circuits from the rest of the braking circuit to create the fail safe when you pull the fuses or they don't have power to them, or they themselves fail? And if so, would they not power up when the key was turned on?

The ABS module does have two paths through it, for the purpose of being possible to disable, operate independently. That is the reason that normal bleeding doesn't easily remove air from the module, the part where the internal solenoid/ABS passages are.

You have a big symptom, you need to track it down now and fix it. I hope the ABS sensor fixes it, I have never had a front hub ABS sensor fail, those should last until the hub fails.


FYI from my past ABS project; I have a 1995 Crown Vic which I converted to ABS ages ago. I opened up the system fully, and installed a 97 4-channel ABS module from a 97 CV, plus two lines to the rear for the extra circuit(without ABS it had just one rear line). I added the needed wiring under the hood and to the dash, and the different rear brake line, rotors, sensors, axles etc.

In the end I had a soft brake pedal after a lot of bleeding. Thankfully I never had any odd symptoms, just a little soft pedal. It was driveable, and I took it easy for months like that, and then used it to deliver mail. After about six months I did the front brakes again, and bled all four too. I got a little air out of all of the calipers, almost nothing from one of the rears. Basically my hard use of the brakes, eventually by ABS function, moved some of the air out into the main lines, where it can be bled.

 

[J_C]

Some people, myself included, believe you can bleed air out of the ABS module by getting the wheels to lockup and energize the ABS, then bleed the brakes again, a couple times if needed (still spongy). I did it in winter while the roads were slippery enough that it took nothing to lock the wheels up. Other people use a gravel road.

I suspect that the ABS light on previously was either due to wrong sensor resistance, or it never working while one half-working, may generate the pulses but fail to do it when they get weaker from slowing down, whether that be from the sensor, or reluctor ring rust or metal particle fouling as mentioned previously.

I'd like to think that with only 1K mi on new hubs, the bearings aren't going out. This assumes everything is good. Correct axle nut torque, decent quality hub. It is better to be in the situation where you know these things, than assume everything was good from a past prior repair where everything wasn't so good so you are now where you are today.

ABS, if there's no power to it, then it can't activate the solenoid that stops pressure to the line for that wheel by activating the solenoid that blocks it. Not sure why people make it out to be more complicated than it is, including bleeding. You could have air in the ABS module and if it isn't purged through normal bleeding, it won't cause a problem in normal braking, not until you already have a wheel speed imbalance (or faux sensor reading) that causes ABS to activate.

 

[M.D. Farragher]

You could have air in the ABS module and if it isn't purged through normal bleeding, it won't cause a problem in normal braking, not until you already have a wheel speed imbalance (or faux sensor reading) that causes ABS to activate.

This makes sense to me. When I get the sensor, we'll find out. The hubs were Motorcraft. No reason to doubt them.

 

[Mordecai]

I recently rebuilt the brakes on my 1995 Ex XLT. New pads in the rear, new extended flex lines, calipers, rotors, and pads in the front, and one new ABS sensor on passenger side. Also replaced the rigid passenger side line in the front as I discovered the fitting was stripped. Bled the crap out of them and have a nice firm pedal. Not everything got replaced at the same time. First the pads all around, then the front flex lines, then the ABS sensor. When I took the vehicle out for a test run the ABS howled and it pulled to the left. I figured I hadn't bled them enough so I did it again. Same hard pedal. Same result. Replaced the calipers and rotors because I was going to do it anyway with 175K on them, and now was as good a time as any. Bled it again, got same firm pedal, and same, ABS howl, and pull to the left. In the meantime I had replaced the rigid line on the passenger side, and wound up with the same result. Pulled the two 30AMP fuses in the relay panel for the ABS, and howl goes away, and vehicle brakes dead true. I should add that there are no ABS lights on dash when the fuses are in place and it is performing badly.

Any ideas or input? ABS module? ABS pump? Can either be tested?

Where did you get the ABS sensor from, and how loud is the ABS howl? I've been trying to diagnose a nasty breaking howl I've had as well.

 

[Mbrooks420]

Air in the ABS module should be able to be purged by simply activating it many times and rebleeding it. All the tool does it activate it in a test mode.

You can also do this with FORScan.

 

[RickOTR]

You can also bleed the ABS system by making a couple emergenmcy stops. This causes the ABS system to activate and bleed all the air out of the system. Just make sure you do it in a safe place where there are no people around. In fact, Manufactures recommend people do this every once in a while to keep the system working properly.

 

[C420sailor]

I do this when it snows. Lots of fun.

 

[jr230]

i bought a 99 ohv v6.5sp ad failure 2times with abs. 1 on a bad road had sand and gravel from torn up asphalt. the 2 on a road had a light sprinkle. no injuries remarkable the plastic bumper had minor blemish .the outer cars slight damage. not long after the abs quit lights been on for 15 yrs
had a 03 with ohc and auto. temp replacement when my car broke down abs light on
junked that one after a year 200k miles 50% towing . 04 now auto v6 abs light on although every once in a wile it will pulse on hard stop . but in my opinion i prefer not to have abs . i have driven 3 million miles urban suburban and some distant but only about 30 k with abs only minor accident with a co focus
light rain stopped but just tapped her bumper scratched on both cars. turned out i found one new tire on front 1 just about legal to drive front wheel drive really needs matched tires on the front. my mileage was in the mid Atlantic and later Florida so all conditions i have encountered . i prefer no abs rather be able to pump brakes my self

 

[M.D. Farragher]

Where did you get the ABS sensor from, and how loud is the ABS howl? I've been trying to diagnose a nasty breaking howl I've had as well.

I apologize for the delay in answering here. Works out the sensor wasn't the problem. The first sensor was bought form Ford, the second sensor was purchased on Amazon. The "howl" was more of a growl, and was just the ABS unit doing it's thing.

 

[M.D. Farragher]

To update my issue here, I replaced the sensor again, and it changed nothing. I assume there is air in the ABS circuit. The scantool I bought didn't work, and neither did my Auto-enginuity tool. Came to discover I need an OBDI tool to do anything on this vehicle. OBDII is 1996 and later. What code reader for a 1995? - Ford Truck Enthusiasts Forums This is a link to a thread on Ford Truck Enthusiasts forum about that. Had to deal with another couple projects and haven't gotten back to this one, but will post when I've had a chance. My issue with the scan tools was no communication. I may take it out and find a nice gravel area to activate the ABS to see if that does it.

 

[Mbrooks420]

If you can activate the pump enough it should purge it. You’re certainly not the first wrap to get tricked by the obd2-like port on the 95’s.