96 Explorer ABS Problem

Ok this is my first post here so be gentle. I have a 96 explorer xlt 5.0 awd. I just got the vehicle used and the problem was there when i got it but the price was awesome for the miles it had. When ever i come to a slow stop the abs kicks in. Even on dry pavement. Sometimes when driving at very low speeds ( -5mph) and not even touching the brake pedal i can hear/feel it kick in and it will stay running till i hit the gas or touch the brake pedal. So far i have done these thing to try and fix the problem:
-Replaced both front hubs/wheel sensors
-Replaced the rear wheel speed sensor located in axle
-Replaced all brake pads and rotors
-Bleed the brake system and flushed with new fluid
-Replaced all shocks ( I know this shouldn't make a difference but they needed to be done anyway)
There are no lights on in the dash and the bulbs(ie brake and abs) are good. I have also tried scanning the system and have found no codes. Please let me know what i should go for next. Would rather not go for the pump with out being able to tell for sure that this is the problem. Thanks for any help.

Just ordered a used pump/control module for $30 on ebay. Beets autozone's price of almost $1154.99. Guess I will see when it gets here. If there is anything that I can check in the mean time than please let me know.

I would run a test procedure on the Throttle Position Sensor just to rule that out.

drdoom said:

I would run a test procedure on the Throttle Position Sensor just to rule that out.

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What is the test procedure for it and was also wondering how it effects the abs system? Thanks

Here hope this helps

TPS Test Procedure

I swapped the pump/control module but still have the same problem. I looked into the throttle position sensor (tps) test but the info in the link is not the same for the 96. My sensor does not look like that and the wire color codes are not the same. Hooked up my scanner though and under live data the tps is shown on a % value. At idle it is showing 18.9% and at wide open throttle it is showing 90%. Doesn't sound right to me so I ordered a tps. Should have it tomorrow. Have been looking for a wiring diagram for the abs system for the 96 awd and have not been able to find anything. Anybody have one? Also the new hubs I put in had metal shims between the wheel speed sensor and the new hub. My old one did not. Anyone see this before? They were FPD hubs from carparts.com part number WH15.515003 Thanks for any help.

slipknotas said:

Have been looking for a wiring diagram for the abs system for the 96 awd and have not been able to find anything. Anybody have one?

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Auto - Online Repair Info
http://search.ebscohost.com/
ID: rrcc
PW: rebsco
Select: Auto Repair Reference Center
Fill in: Find Your Vehicle
Follow prompts down to Wiring Diagrams.

Replaced the throttle position sensor and still no luck. I'm lost no idea were to go next. *#$%!!!!!!!!!!!!!!!!!

Does anyone know what the correct ohm readings should be for the front hubs on 96 explorer AWD? Also I think i heard somewhere on hear about an AC voltage test on these hubs. Think they generate an alternating AC current when spun, can't remember though?
Update: (for those having the same problem) Going to recheck the new right front hub tomorrow. Found that my wheel pulls slightly to the left when the abs kicks in. Read this TSB I found on here:

http://www.blee1099.com/tsb_98-14-8.pdf

Next new update: I started by ohm checking the old hubs that I still had. One hub was around 0.395 and went up to 0.410 when rotated. The other started at 0.410 and then went open loop when rotated ( This is the one I figured was bad and caused the original problem). Next I went to the new hubs that are currently on the truck. Driver side went from about 0.430 to open loop when rotated. Passenger side went from about 0.430 to 0.445 when rotated.
My next step was to use the cable from my old hub that did not go open loop and place it on the driver side hub but when i rechecked now this cable also went 0.410 to open loop when rotated. So I placed two shims that came on the new hub (shims were placed between hub and wheel speed sensor) on the old speed sensor and placed it on the new hub. No more open loop when rotated and reading was close to what the other side had. Figured this would solve the problem.
BUT NO!!!!!!
ABS is still kicking in on slow stops. Might just have to bite the bullet and spend another $210 for another set of front hubs from autozone this time.
I refuse to let this beat me but unless someone out there knows what these sensors should be reading I guess that is what I will have to do.

No one knows how to ohm check the front hubs and what they should be reading??????

slipknotas said:

No one knows how to ohm check the front hubs and what they should be reading??????

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When hubs rotate they are essentially AC generators. Test using the AC feature on the multitester. At rest they are measured in ohms (coils).

Another thing is to wiggle the wires a bit when you do testing, I had a hard to track down ABS issue on a Lincoln that turned out to be a bad wire. There could also be wiring issues going to the abs computer. Without a wiring diagram you would have to disconnect the harness from the computer and try to find the pin that leads to the sensor by trial and error. Again, twist and manipulate the harness while you test.

You may want to test those sensor wires under load (disconnected from the computer with a test lamp). What could happens is one wire is corroded away and connected by a single strand, so it may pass a low current resistance test from your meter but can't pass the lower current when your wheel is spinning very slowly. Now your computer senses (at very low speed) that a wheel is locked up, because there is no signal). now the ABS goes on, and no warning lights come on because the system was tricked!

Finally there are expensive scan tools that can read each wheels sensed MPH.

The problem is for sure in the wheel speed sensors in the front as seen from the data in my last post. There was to different reading on the new sensors. One side had two different ohm reading when rotated (0.430-0.445ohms) and the other had an ohm reading and then an open loop when rotated (went back and forth). So wich way should it be? What would the correct ohm reading say for the 96 with AWD? If I do the AC test what should the reading be? Thanks

slipknotas said:

The problem is for sure in the wheel speed sensors in the front as seen from the data in my last post. There was to different reading on the new sensors. One side had two different ohm reading when rotated (0.430-0.445ohms) and the other had an ohm reading and then an open loop when rotated (went back and forth). So wich way should it be? What would the correct ohm reading say for the 96 with AWD? If I do the AC test what should the reading be? Thanks

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From the service manual:
-------------------------------------------------------PINS
RF Brake Anti-Lock Sensor Resistance (AWD, 4x4) Off 23 and 36 Kilo-Ohms 0.387-0.473 Kilo-Ohms
LF Brake Anti-Lock Sensor Resistance (AWD, 4x4) Off 24 and 25 Kilo-Ohms 0.387-0.473 Kilo-Ohms
Rear Brake Anti-Lock Sensor Resistance Off 21 and 22 Kilo-Ohms 0.8-3.5 Kilo-Ohms

Note: To check brake anti-lock sensor output, measurements of both the frequency and the voltage output must be taken. The actual speed the wheels are turning is not important — the result of voltage output divided by the frequency will not change with wheel speed. However, it is crucial that both the frequency measurement and the voltage output measurement be taken at the same wheel speed.


Rotate Front Wheels and Rear Axle @ 60 RPM
RF (AWD, 4x4) Off 23 and 36 Hz and mV 3.0 mV/Hz or Greater
LF (AWD, 4x4) Off 24 and 25 Hz and mV 3.0 mV/Hz or Greater


Also

Remove suspect front disc brake hub and rotors; refer to Section 204-01A (4x2) or Section 204-01B (4x4, AWD), and Section 206-03 .
Verify the tone ring is pressed straight and fully onto the hub.
Remount the suspect front disc brake hub and rotor.
NOTE: Feeler gauges can be mounted to a welding rod and inserted between the vanes of the front disc brake hub and rotor to measure air gap precisely.
Measure the air gap between the brake anti-lock sensor and the tone ring teeth. Repeat in at least two more wheel positions.


Is the gap consistent and less than 1.78 mm (0.070 in)?
YES
GO to G5 .

NO
REPLACE tone ring.

Thank you so much!!! Can't measure the air gap however, in the 96 awd the tone ring is sealed inside the hub assembly. Going to test tomorrow again to see what side is bad, replace both hubs with autozone duralast hubs and then save what ever hubs are good for spares and junk the rest. No more buying parts from carparts.com for me.

slipknotas said:

Thank you so much!!! Can't measure the air gap however, in the 96 awd the tone ring is sealed inside the hub assembly. Going to test tomorrow again to see what side is bad, replace both hubs with autozone duralast hubs and then save what ever hubs are good for spares and junk the rest. No more buying parts from carparts.com for me.

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Did you pull an AC reading off those sensors? An OHM reading when they move is very misleading, and probably random (but still could be the culprit).

Before the trouble of pulling the hubs, I would check that the wires are in good shape. Does the AC signal you get at the sensor leads match the one at the indicated pins in the harness by the ABS unit?

If not for you it may help someone in the future...

I also got the ford service data on disk and found that diagram in there. Wires tested good last night but thank you for posting that for people in the future.

Update: So I tested the hubs last night and found that it was the right front FPD hub that was bad from the factory. Found that on the ohm test reading should go open loop and then a 0.387-0.473 Kilo-Ohms reading when rotated. Pulled two of the shims out from under the sensor and got a reading that should work but i didn't bother to test drive it to see. I just went ahead and replaced both with the duralast hubs I got at autozone. Went for a test drive and problem was solved. Or so I thought. After about 5 miles of driving the abs light came on, so I pulled over and checked the code. C1145 right wheel speed sensor input malfunction or something like that. Got underneath and checked the abs sensor harness and all was good. Got home at checked the sensor with the fluke meter and it had went bad. Going to go take it off and take it back to autozone now.
FML this is getting so annoying right now.

something "weird"???? those sensors are basically "inductors". You can usually only get valid resistance measurements on them in a "static" mode (ie. nothing turning, nothing connected ... ie disconnected harness). As suggested, once things are turning, you need to read a voltage as in AC to see what going on (plus frequency which is another problem).... the one question would be... where are you taking your measurements (ie. at what point in the wiring)????

From the trouble shooting section... IF you see "Open or shorted front left speed sensor coil" (I assume applies to both sides), you have a problem.

What do you mean by "the ABS is kicking in"? Are you saying that the pedal is pushing back on you when you hit the brakes?

Budwich: I understand that but this is what i found. Ohm testing when rotated caused open loop then a reading of 0.387-0.473 Kilo-Ohms ( would go back and forth). With both sensors working like this there were no problems. With a sensor not going to open loop and just giving two different ohm values when rotated there was a problem with low speed abs kicking in. I also understand that the ohm testing can be misleading but this is what worked for me. I took the readings from the abs harness that comes off the hub. I also checked the wires using the wiring diagram listed earlier and checked the wires at the abs pump/control module connector. They were the same.

jremington: by abs kicking in I am meaning the abs system is activating /thinking that a wheel is locking up and turning on the abs pump. I wouldn't say the pedal pushes back (maybe a little) but more of a fast vibration. You should be able to hear your abs pump running. Mine definately was the abs system.

UPDATE: After exchanging the right front duralast hub at autozone all is well.
So the moral of this story is to use ford oem hubs or if you want to go the cheap way like I did you had better test the hubs before assuming the new hubs you put in are good and going on to other abs components. I got two bad sensors that were brand new. Thanks to all that helped!!!!!!