Tony302600 Posted September 17, 2008 Share Posted September 17, 2008 I have a 2005 F-250 2wd, with the usual abs light on c1236, c1175. I performed the tsb 07-9-8 for that concern, found the abs ring in the rear end out of spec per the .010'' measurement against the ring gear. Adjusted it and inspected the teeth, test drove it, after 10-15miles the abs light comes on and the signal was extremely erratic and not consistant. Previous tech here already replaced the rear dif sensor, and pigtail. I run through hotline and do all the test's, they tell me to run all new wire including new pins at the abs connector...did that, replaced the ABS module, did that, check amperage readings inline on that ckt, did that. And cleaned off the rust on the sensor housing. I drove it for 10 miles, apprentice drove it for another 10 miles. light didnt come on, thought i fixed. this morning guy calls said 8 miles away the light came on. I'm at a loss here, i can't figure this thing out, everything adds up except the stupid light comes on for the rear sensor. I have no idea what to do, and i already tried giving it back to the other tech because it left here with the light on in the first place. /forums/images/%%GRAEMLIN_URL%%/whattodo.gif Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 17, 2008 Share Posted September 17, 2008 Tony, could this rear sensor be picking uo some sort of RF interference? Is this a modified truck? strobe lights? Or is it possible that a coil is causing RF interference? I had one a while ago, but I would get a dtc for the relay in the abs module and it would happen as soon as I accelerated. You mentioned that the signal for the rear sensor was erratic. Did it get better after you replaced the wiring and module did the reading get better? Quote Link to comment Share on other sites More sharing options...
mchan68 Posted September 17, 2008 Share Posted September 17, 2008 Don't know if this will help much. I had one that came in, about three years ago for an ABS light on and speedometer inop. This was on a 2000 F-350 with a 7.3L six-speed manual with rear ABS if it matters. This was a vehicle that came in from a "garage" that couldn't fix the problem before it landed in my hands. Dash was already partially disassembled, the main harness connector to the module had multiple backprobe marks on various wires. The problem in the end, was a loose main ground connection on the body fenderwell. Tightened the ground eyelet bolt, and voila, problem was fixed! Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted September 17, 2008 Author Share Posted September 17, 2008 Tony, could this rear sensor be picking uo some sort of RF interference? Is this a modified truck? strobe lights? Or is it possible that a coil is causing RF interference? I had one a while ago, but I would get a dtc for the relay in the abs module and it would happen as soon as I accelerated. You mentioned that the signal for the rear sensor was erratic. Did it get better after you replaced the wiring and module did the reading get better? The problem is that it's so erratic and int. that i can't get anything to duplicate it. It's just a regular cab F-250 2wd nothing special with no addons other then a reverse beeper. The FSE is coming out but they think its a dif case issue after all my findings and results that i gave back to hotline. If it is a case then the customer is gonna be SUPER pissed because its CP. Things ive learned while dealing with hotline. The engineer is awesome, his name is Ben. This 05+ years are a amperage limiting system meaning 7mA when it sees a tooth and 14mA when it doesnt. The ABS module calculates how fast it switchs and walla you have a speed signal. You have to test this with your DVOM inline and the CKT operational. Plus, you have to slowly move the wheel so you can see the DVOM readings. On the pre 05 years, they used a voltage producing system in which the sensor would generate voltage. If you suspect a airgap issue, you would remove the 2 pins at the ABS module for the rear sensor, hook up your leads with ure DVOM and use the Hertz setting. 18-22 HZ = 1 mph. if you are going at 1mph and only have 10 hz then you know you have a airgap issue. I'll let you know what happens when i find out when the FSE will come out. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 17, 2008 Share Posted September 17, 2008 I would pull that exciter ring out and look it over with a magnifying glass, them things are stupid sensitive to knicks and what not. I'm having trouble believing the case is a problem but who knows. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted September 18, 2008 Author Share Posted September 18, 2008 We'll have to wait and see. /forums/images/%%GRAEMLIN_URL%%/popcorn.gif Quote Link to comment Share on other sites More sharing options...
DamageINC Posted September 19, 2008 Share Posted September 19, 2008 I'm interested to know what you find... it almost sounds like it's more likely that the sensor isn't seating properly IN the case and the gap between the sensor and the exciter ring isn't what it should be. Or maybe the new sensor itself isn't any good or is incorrect. (Or it's just that the carrier bearings are so worn out that the whole assembly is bouncing around in the case, lol! Customer states "orange glowing from rear of vehicle after long trip") Dave Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 20, 2008 Share Posted September 20, 2008 is this thing gas or diesel? Whoops!! One large step backwards... this is an 05 and RFI should not be an issue... even though the wiring diagrams show 519 and 523 as a twisted pair. When I am faced with these things, I go right back to the beginning... The tech you took over from may see it as an insult.... Too bad, so sad... "The beginning" is going to include checking sensor polarity... The beginning means that we are going to look at this thing with our mind and our eyes wide open... Do not ask the other tech what he checked nor how he checked it... it doesn't matter because you need to see for yourself. We all have a profound ability to make mistakes and overlook important things... The chance that two of us will overlook the exact same thing is only there if we place absolute faith in everything that has been done to this point. Since the danged thing ain't fixed, we begin from the beginning. FWIW.... if I am handed the keys to something, there is a very good chance we already have too many hours into something. I'm not "good"... but I try to be thorough.. question everything.. trust only your own eyes. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted September 22, 2008 Author Share Posted September 22, 2008 Well Jim, i did do all that and take your advice about not overlooking and starting from scratch, did the tsb from step one. The way to test this sensor is from the way i described it above. Like i said, can't wait see what super cool (sarcasm) problem i find. Quote Link to comment Share on other sites More sharing options...
LARRY BRUDZYNSKI Posted September 22, 2008 Share Posted September 22, 2008 HMMMM!!! I've got a idea..... /forums/images/%%GRAEMLIN_URL%%/flamethrower.gif Just kidding. /forums/images/%%GRAEMLIN_URL%%/grin.gif I been thinking about this one if the signal is intermittent I think I would be looking for a ground problem or maybe a chaffing issue somewhere. Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted September 22, 2008 Author Share Posted September 22, 2008 I have brand new wires, new pins on both ends of the CKT. checked pin fitment even with the new pins....ok. The sensor isnt perfectly erratic. It will drop out for 5-10 seconds then come back, then get realy erratic, then drop out again for a while. Nothing i do at that time seems to affect what it's doing. I was ok because i gave my 2 weeks on friday, so i really didnt care, but after the manager talked me outta leaving and a new payment plan only for the truck guys thats appealing to me and no one gets screwed /forums/images/%%GRAEMLIN_URL%%/thumbup.gif We'll see what happens. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 24, 2008 Share Posted September 24, 2008 Is this thing gas or diesel? Quote Link to comment Share on other sites More sharing options...
Tony302600 Posted September 24, 2008 Author Share Posted September 24, 2008 6.0L Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 26, 2008 Share Posted September 26, 2008 Whoops!! One large step backwards... this is an 05 and RFI should not be an issue... even though the wiring diagrams show 519 and 523 as a twisted pair. Jim, Why should RFI not be a problem? I would think if there were an issue with the sensor gap, the problem would not be intermitent. We know that the wiring from the sensor to the module is good. The module and the sensor are new. I think this is a ground issue of RFI is interfering with the sensor signal. Here is another thought... What if you just have another bad sensor. Kind of like Jim was saying, don't assume anything. I work with a guy that one time had a car that had a bad DPFE sensor. He replaced it and the car came right back. The dummy mixed up the new and old part and ended up putting the bad part back on the car. /forums/images/%%GRAEMLIN_URL%%/boink3.gif Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 26, 2008 Share Posted September 26, 2008 Quote: The dummy mixed up the new and old part and ended up putting the bad part back on the car. Looks like that guy coulda used a little more of this /forums/images/%%GRAEMLIN_URL%%/coffee.gif Quote Link to comment Share on other sites More sharing options...
Mekanik Posted October 2, 2008 Share Posted October 2, 2008 Or maybe a little less of this: /forums/images/%%GRAEMLIN_URL%%/drinkingdude.gif /forums/images/%%GRAEMLIN_URL%%/cheers.gif Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted October 4, 2008 Share Posted October 4, 2008 James... my first inclination was to consider RFI from a bad COP since I've seen this several times on Super Duties... But 05 was the first year for the new active wheel speed sensor that was supposed to alleviate many of these concerns.... But you are right... we shouldn't discount any possibilities without proof.... There remains the possibility that even an alternator can bestow odd concerns on us.... I am always concerned when I get the exact same symptoms back after a parts replacement.... While 'new' only means 'never before used' these days.... it is still ever so easy to overlook something in the course of diagnosis.... Quote Link to comment Share on other sites More sharing options...
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