fleurys Posted February 3, 2017 Share Posted February 3, 2017 (edited) Hey guys... It's funny how life goes... this ime , I need some advice with my 2003 pathfinder with VDC (Vehicle dynamic control)... Bare with me.. Abs light comes on, I have an autel maxi diag than can read and clear abs code from nissan. It tells me that it is not receiving signal from the front right sensor. After verifying live data with my autel scanner, I confirm that the abs sensor gives no reading when the wheel is turned. Following the the troubleshooting procedure from the FSM (BR-120) did not give good results as the manual states than a resistance of 0 to 0.5 Ohms. When I measured my sensor it reads 5.2M ohms... ( I suspect that these sensor are digital and not analog because of the VDC option.. and that the manual is wrong on this part)... That's quite a large difference... but then all my sensors were giving the same reading... so I went on to remove the FR sensor and look at the tone ring. Tone ring looks good but there was alot of rust dust and some minor size flakes... I believe this was not changed since 2003... I blew some compressed air in the hub and quite alot of rust dust came out. Put back the sensor in, redid the live data test and now the sensor do register wheel speed... Hooray... not so fast... Cleared the codes and went for a test drive. Everything worked properly (the abs engages when detecting wheel blocking), the VDC and SLIP do engage when wheel spin and or sliding is detected... I thought I was done... Went on the highway... lights came back... Read the code : C1115 ABS Sensor... Now I do not have anymore the wheel sensor as a fault but more of a general one... I decide to plug the Autel, put it in live data and then go back on the highway.. The results are what is baffling me a bit.... When I stay under 45-50 mph, all wheel sensor report the same speed, as soon as I go more like 60mph, the right front sensor starts shooting false reading. (Ex: 60,60,12,60,60,60,9,60,60,7,etc..) eventually is starts showing continuously a very low speed like 2-3 mph... when I go down back to 35-40mph, everything is back to normal as for the speed reporting... MY QUESTION TO THOSE WITH THE EXPERIENCE : Is it possible that a (possibly digital) ABS wheel sensor only malfunction at high speed ? Has anybody here witness this ? I need more reassurance before I fork 200$ on a sensor.... Thanks again S. Edited February 3, 2017 by fleurys Link to comment Share on other sites More sharing options...
Citron Posted February 3, 2017 Share Posted February 3, 2017 Digital, ( Hall effect) has a wire with a reference voltage. You could test the wires and see if one has voltage, that would tell you if it is digital or not. If it has three wires, definitely digital, but not all digital have three wires. In my experience, when they malfunction, it is across the board, not just high speeds. This makes me think something else is going on. Is the air gap between the sensor and tone ring correct. There should be a spec for that in the FSM. I have seen flakey rpm signals on hydroelectric generators due to improper air gap. Bad or loose wheel bearings can cause faulty signals, since the tone ring is not rotating in the correct plane. That may change as speed increases. Bad connections can cause problems, but I don't see why that would change with speed. Hope this helps. Link to comment Share on other sites More sharing options...
McFalconPunch Posted February 3, 2017 Share Posted February 3, 2017 When I bought mine the ABS light was on. A friend of mine has a Snap On SOLUS at his disposal so we hooked it up and took it for a drive. The signal was good until you got to higher speeds, then it gave sporadic signals or none which led to my ABS light being on. We inspected the sensor and there was a minor break in the covering for the wiring which let water in. The break wasn't that big at all, but the wires were corroding. I replaced the sensor and it hasnt came back on for the past 5 months. Link to comment Share on other sites More sharing options...
fleurys Posted February 3, 2017 Author Share Posted February 3, 2017 Digital, ( Hall effect) has a wire with a reference voltage. You could test the wires and see if one has voltage, that would tell you if it is digital or not. If it has three wires, definitely digital, but not all digital have three wires. In my experience, when they malfunction, it is across the board, not just high speeds. This makes me think something else is going on. Is the air gap between the sensor and tone ring correct. There should be a spec for that in the FSM. I have seen flakey rpm signals on hydroelectric generators due to improper air gap. Bad or loose wheel bearings can cause faulty signals, since the tone ring is not rotating in the correct plane. That may change as speed increases. Bad connections can cause problems, but I don't see why that would change with speed. Hope this helps. Thanks for the comment.. I'll go back at it and verify if there is voltage on the sensor.. As for the air gap, I know there is alot of crust rust on the knucle and I think I did not give enough attention to make sure the seating of the sensor was perfect... So I will get at it again.. One question regarding you faulty signals on hydroelectric generators : Did the signal was faulty throughout the rpm range or just higher ones ? Link to comment Share on other sites More sharing options...
fleurys Posted February 3, 2017 Author Share Posted February 3, 2017 When I bought mine the ABS light was on. A friend of mine has a Snap On SOLUS at his disposal so we hooked it up and took it for a drive. The signal was good until you got to higher speeds, then it gave sporadic signals or none which led to my ABS light being on. We inspected the sensor and there was a minor break in the covering for the wiring which let water in. The break wasn't that big at all, but the wires were corroding. I replaced the sensor and it hasnt came back on for the past 5 months. Thanks, I will take another look at it... Link to comment Share on other sites More sharing options...
fleurys Posted February 3, 2017 Author Share Posted February 3, 2017 The other thing that I read was a possible crack in the tone ring which can make it expand at higher speed, therefore changing the air gap for the sensor... Did anyone had to change a tone ring on his pathfinder ever ? (They don't seem to be problematic like other makes of truck or car)... Link to comment Share on other sites More sharing options...
McFalconPunch Posted February 3, 2017 Share Posted February 3, 2017 The other thing that I read was a possible crack in the tone ring which can make it expand at higher speed, therefore changing the air gap for the sensor... Did anyone had to change a tone ring on his pathfinder ever ? (They don't seem to be problematic like other makes of truck or car)... I never changed mine and I had to take a torch to the sensor to get it out. Link to comment Share on other sites More sharing options...
Citron Posted February 3, 2017 Share Posted February 3, 2017 Thanks for the comment.. I'll go back at it and verify if there is voltage on the sensor.. As for the air gap, I know there is alot of crust rust on the knucle and I think I did not give enough attention to make sure the seating of the sensor was perfect... So I will get at it again.. One question regarding you faulty signals on hydroelectric generators : Did the signal was faulty throughout the rpm range or just higher ones ? It was throughout the range. I personally have never seen a speed sensor, on vehicles or other things, that only acted up at the higher end of the range. Sounds like Mcfalconpunch has experienced it, so that may be a good place to start. Link to comment Share on other sites More sharing options...
fleurys Posted February 4, 2017 Author Share Posted February 4, 2017 (edited) **UPDATE*** Thanks guys for your comments and feeling about this... The problem is now fixed and it did not cost anything.... It was my first rodeo troubleshooting abs and I learned alot here in the last few days... A live data tool is absolutely necessary in order to not blind troubleshoot on this... Since at first, my signal was 0 then after removing the rust in the knuckle abs hole , it gave me back a signal (but only on low speed) , made me think twice about the importance of the rust in this issue. This morning I lift the truck again and started inspecting the cable carefully like mcfalconpunch said... The cable was impeccable with no visible signs on wear or tear. The connector was clean and the pins showed no signs of rust or water infiltration. Then looking at the sensor itself.. I compared with the left wheel (working one), the status of the seating of the sensor. I could see that the right wheel (faulty sensor) was not seating as <flush> on the knuckle as the other one. I removed a good 1/16" of rust where the sensor sits. Whit the years, it had basically <lifted> the sensor from its seating position. Like I said, i'm new at troubleshooting abs and did not think twice when I saw it at first.... I chipped the rust with a screwdriver and hammer, then sanded it. I also had to use a dremmel on the inside of the abs sensor hole because even there the rust had made the inside of the hole smaller and was preventing the abs sensor to insert fully... Once everything cleaned, the sensor was now sitting flat on the knuckle therefore the sensing part of the sensor was at least 1/16" to 1/8" lower in the knuckle . I cleared the abs code, ran the 4x4 transfer case diagnostics in order to erase the 4x4 light (the code was vdc related because of the abs malfunction), then went back on the road. Tested it up to 85mph and no more drops of the signal. The live data shows a perfect coordination between all wheels now. So for everyone out there, before buying a 200$ sensor, have a look at the seating position of your abs and I would suggest investing in a obd2 scanner that has live data and that can talk to specific manufacturer systems. I personally just bought the Autel MD802 All Systems. paid 237$ CAD on amazon... It paid for itself just with this repair... Cheers, Edited February 4, 2017 by fleurys Link to comment Share on other sites More sharing options...
Citron Posted February 4, 2017 Share Posted February 4, 2017 Awesome. Yeah, the air gap distance is critical on speed sensors. I am glad you found the problem. Link to comment Share on other sites More sharing options...
fleurys Posted February 5, 2017 Author Share Posted February 5, 2017 Yeah ... Your comment about the air gap combined with the rust gave me the idea of cleaning the knuckle .. Envoyé de mon iPhone en utilisant Tapatalk Link to comment Share on other sites More sharing options...
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