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Discussion Starter · #1 ·
My 2002 Rodeo (V6 engine) has about 162K miles. I replaced the front brake pads and rear brake shoes and wheel cylinders a little over two years ago. I also flushed the entire brake system with fresh brake fluid. The fluid level in the brake cylinder reservoir has only dropped slightly, which I attribute to wear on the pads and shoes. The brakes feel solid although my wife and I both drive conservatively.

About a year or so ago, the ABS warning light started coming on sporadically. It usually went out during the next starting cycle. Recently, it has been on every time I drive the car. No other warning lights are on and the brakes still feel solid although I have not tried them on a hard stop.

Any suggestions or insight would be greatly appreciated.

Thanks,
David
 

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The ABS Warning Lamp will illuminate when the ABS electronic module detects a component failure in the system. When the fault is cleared, the ABS electronic module will turn Off the ABS Warning Lamp when vehicle speed is greater than 9 mph.

Intermittent illumination of the ABS Warning Lamp suggests that there is wiring problem caused by a broken wire or loose connection to one of three ABS wheel sensors. The typical place for a wiring problem on a Rodeo like yours is in the rear ABS sensor wiring harness. The rear ABS sensor is on top of the differential and the wiring runs along the left axle tube, up along the LH trailing arm to the LH frame rail. The trailing arm moves up and down as the truck hits bumps in the road. This eventually the wires in the ABS harness will break at the flex point where the wires transition from the trailing arm to the frame. The wires break inside the insulation so you can't see the break, use an ohm meter to test the wiring. Use a scan tool/reader to retrieve the ABS Diagnostic Trouble Code (DTC) or use a jumper in the DLC to initiate the flash code diagnostic. The scan tool makes it a lot easier to retrieve the failure codes than the flash code method.

The hydraulic braking system still works normally when ABS is inoperative.
 

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Discussion Starter · #3 ·
Thank you for your suggestions. I used a jumper between ports 4 and 12 on the OBD connector to get the 'flash' codes. I found
15 - High or low ignition voltage
35 - Open or shorted relay circuit
52 - Open or shorted FR sensor
62 - Missing FR sensor signal or sensor signal dropping out.

This looks like a problem on the front passenger side. It might be a wiring problem. About 9 months ago I replaced the ball joints and tie rod ends. I had to remove the wheel assembly from one side to drive out the ball joint. It may have been the passenger side, but I'm not completely sure. I do remember having to disconnect a wire connection which was probably the speed sensor. I also don't remember if the ABS light was coming on once in a while before that.
 

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On my 02 Rodeo Sport I disabled the ABS and drove it for several years with it disabled. I also turned Off the Warning Lamp.
 

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Discussion Starter · #5 ·
The Rodeo is mainly my wife's car and she drives very carefully. I don't think it has been in a situation where the ABS would be activated. I'm willing to fix it if it isn't too expensive or labor intensive. I bought the Rodeo new in 2002 and it has been the most trouble-free vehicle I have ever owned. For now, we will keep driving it until something happens that is just too expensive to be worth fixing.
 

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It is easy enough to check the wiring between the ABS electronic module and the ABS wheel sensor and the sensor itself. There are only two wire per ABS sensor.
 

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Discussion Starter · #7 ·
Thank you for your comments and insight. I plan to change the oil this weekend and can check the wiring for the speed sensor while I'm under the vehicle.
 

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jessidog said:
Thank you for your comments and insight. I plan to change the oil this weekend and can check the wiring for the speed sensor while I'm under the vehicle.
You likely will need to use Multimeter to determine if there is a problem. You can check the sensor resistance at the ABS module connector. Pins 1-8 are A and 9-16 are B. Measure across pins 3 and 11 for Right Front sensor.
 

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Discussion Starter · #10 ·
Just following-up on my ABS warning light situation in my wife's 2002 Rodeo. As I posted previously, the ABS codes indicated a problem with the front right (passenger) side wheel speed sensor. My manual says that the resistance of the sensor should be 1.3-1.9k ohms. I measured 187k ohms, about 100-fold higher resistance. I ordered a new sensor from Rockauto. I was surprised at the cost difference between the front and rear sensor. The front wheel sensor I bought was $200. There was another sensor that was nearly $400. But the sensor that fits in the differential is only around $30-50.

If I understand correctly, the ABS warning light will go once the vehicle reaches 15 mph or so after I install the new sensor - if that is the only problem. Is that right?
 

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The ABS Warning Lamp will turn OFF at around 9mph if all the faults have been cleared.
Did you re-measure the sensor resistance at the sensor connection to ensure you don't have a wiring problem or corroded electrical connectors.
 

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Discussion Starter · #12 ·
I measured the resistance at the sensor connection on the steering assembly. The connection looked clean with no signs of corrosion. The troubleshooting chart in the manual said that the sensor is defective if the resistance is not between 1.3-1.9k ohms.
 

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Discussion Starter · #13 ·
The situation got more complicated. I bought the front wheel sensor from RockAuto. There was only one option for the sensor and it looks the same as the one sold by other vendors. It would mount in the wheel hub with a single bolt which is the way it is shown in two different versions of the service manual that I have.

The service manual that I usually use shows a drawing and describes replacement of a speed sensor that looks like the one I bought. In a different version of the service manual I found the same drawing and description. But there was a two sentence comment that some models (especially the 2WD like mine) have the sensor integrated into the wheel hub that must be replaced as an assembly. This is what it looks like on my car.

The two sensors listed on RockAuto cost $202 (the one I bought) and $378. Interestingly, the wheel hub assembly with the integrated ABS speed sensor is considerably cheaper. There are several options in the price range of $60-100. The pictures of the wheel assembly on RockAuto look exactly like the one on my vehicle.

There is a chance that the high resistance is due to a problem with the wiring connection on the wheel hub. But I doubt that since the connector is tight, it has never been disconnected and there are no signs of corrosion or damage. So I'll replace the wheel hub and see what happens with the ABS system.
 

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Discussion Starter · #14 ·
This morning I noticed that the ABS warning light has suddenly turned off. It's not a burned out warning light because it does come on when the key is in the run position along with all of the other warning lights. I drove around for a little while and the light never came on. I'm guessing it is an intermittent issue with the speed sensor. I already have the new wheel hub (with the integral speed sensor) which cost a little less than $100. It would likely cost $25 or so to return it to RockAuto and the vehicle does have over 160K miles. So I think I will go ahead and install it when I get a chance.

While the ABS warning light is off, is there a safe way to determine if the ABS system is actually working?

Thanks,
David
 

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jessidog said:
While the ABS warning light is off, is there a safe way to determine if the ABS system is actually working?
ABS is intended to prevent the wheels from locking up on hard braking. If you jam on the brakes at 50 mph more or less you should feel the brake pedal pulse as the ABS "computer" rapidly applies and releases the brake calipers to prevent lockup.
If the ABS Warning Lamp illuminates at startup and quickly turns Off the ABS passed the self test and should be working. If the Warning Lamp is continuously illuminated when driving the ABS is inoperative.
 

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Discussion Starter · #16 ·
The ABS warning light is back to being on intermittently while driving. Thank you for the information on how to test whether it is working after I replace the wheel hub which should (hopefully) solve the issue based on the codes.
 

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Discussion Starter · #17 ·
Yesterday I decided I would finally get around to changing the right (passenger side) wheel hub since the ABS warning light codes indicate a bad wheel speed sensor. On my 2002 Rodeo, the ABS speed sensor is an integral part of the wheel hub. I seriously underestimated the amount of corrosion holding the wheel hub in the steering knuckle. I removed the brake caliper and four bolts (10mm hexagonal head) holding the wheel hub. I first tried a sharp chisel at the point where the wheel hub contacts the steering knuckle. That approach failed spectacularly. I got a 5-lb slide hammer (loaner from Advance Auto) that I was sure would work. Lots of PB Blaster and pounding with the slide hammer for about an hour did not budge the wheel hub.

I watched a few You Tube videos. This seems to be a common problem over a range of vehicles, the most severe when the wheel hub and steering knuckle are different metals. One creative approach was a large pipe wrench hooked over the rotor and then hit with a sledge hammer. Unfortunately, that method did not work.

So I put everything back together since I need a new approach. As Einstein said, doing the same thing over and over and expecting a different outcome is the definition of insanity. For now, I think I will spray a little PB Blaster on the joint every day for the next few weeks and hope that it slowly works it magic to loosen the corrosion. Is there something better than PB Blaster? Any other ideas?

Thanks,
David
 

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If reasonable, I would try heating it with a torch WHILE hitting it with a hammer. Heat, hammer, heat, hammer, if you have a buddy to hold the touch, both at the same time.
 

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You're going to need air tools.

Remove the large axle nut. Take the 4 bolts out of the flange. First see if you can get the whole assembly to rotate a bit in the knuckle (air hammer). If you remove one of the wheel lugs, you should have room to put a long bolt with a jam nut through the lug hole and against the knuckle with the nut against the back of the hub flange. Hold the nut with a wrench and tighten the bolt (preferably with an impact wrench). You can use this method to 'jack' the hub bearing out of the knuckle. You can remove a couple of lugs and go on opposite sides for better leverage, or switch from one side to the other.

Sometimes this will pull the hub flange out of the bearing, so I'd see if I could get it to rotate first. That should break the corrosion bond, and rotation is easier than trying to pull it straight out with no leverage.
 

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Discussion Starter · #20 ·
Thank you for your suggestions. My Rodeo is a rear wheel drive and does not have a large axle nut. I saw a video using your suggestion to press out the hub with a large bolt. If I was replacing the hub because of a failed bearing I would try heat, a big hammer or any of the other highly aggressive approaches. However, I am attempting to replace the hub only because the ABS warning light concerns my wife while she is driving. Any of these methods would commit me to finishing the job since I would very likely damage the hub in the process of removing it. As is, the car is still drivable; it just doesn't have a functioning ABS.
 
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