opposite PID readings,fr wh sp sens

STROKER_T · June 21, 2009

Hello again,was wondering if anyone has ran into this?

Working on an '05 F250 4 x 4 with a C1145(right front wheel speed sensor)code,so I did the prelim checks on the right front,raised the vehicle,engaged the 4 x 4 so I could watch the front sensor PIDS while doing wiggle checks...now for the interesting part.

I disconnected the R/F sensor at the mud flap,and sha-zam,the LEFT front sensor PID goes to 0.00V...never seen that before,its bass-ackwards!

I then replaced the L/F sensor,problem solved?

I'm guessing that maybe the pins at the abs module are switched,and that as long as the sensors are functioning properly,it wont cause any issues UNLESS its being diagnosed for a similiar concern.I didnt go crazy finding out WHY the sensors read opposite,vehicle is out of warranty,customer in a rush,etc.

That was last week,ABS light has not come back on,what do y'all think? Posted Image

Brad Clayton · June 21, 2009

Seen it quite a few times before. It's a common trick when isolating a wiring concern on these newer Super Dutys. The only problem is the guy working on it can forget to switch the wires back at the module when done.

STROKER_T · June 21, 2009

Thanks Brad,it was definetly a learning experience for me.From now on I'm gonna disconnect one side just 2 make sure the correct sensor is identified... Posted Image

Jim Warman · June 21, 2009

OMG.... imagine what might happen in a full bore, ABS active, panic stop situation?

STROKER_T · June 21, 2009

Thanks for the ever so short insight Jim,always a true pleasure reading your antics...even though its reads as if your being a smart ass. Posted Image

Just kidding Jim,especially after understanding how much good sense you make...had to read into it a bit... Posted Image

Aaron · June 22, 2009

OMG.... imagine what might happen in a full bore, ABS active, panic stop situation?

+1 This is gonna direct the HCU to modulate pressure to the wrong wheels in a skid/slip situation, methinks.

STROKER_T · June 22, 2009

The customer that owns this truck is a really good one,so I'm wondering if maybe it might be best to have him come back in so that this bass-ackwards PID thing can be rectified.Good customer or not,this sounds like it could be a major safety concern,not cool. Posted Image

'05 F250,60k,no previous HCU problems up 'til now,and it's an assumption that makes me think it's an HCU problem anyway...as I have'nt seen this before,but surely it's not the only truck riding around with opposite front sensor PIDS.

Which makes me curious,is this something that occured with a certain build date or batch,and what would be the least intrusive way of finding and fixing,really fixing the problem? Posted Image

BrunoWilimek · June 22, 2009

I would check the main harness connector at the ABS module and compare the wire colours to the wiring diagram to confirm if the wires are crossed at this connector(C135). If so, just switch the incorrect ones to the proper locations. If they turn out to be correct, then you have a real mystery. According to the diagram, pin 12 CKT 521 (TN/OG) is the wheel speed sensor LF + and pin 13 CKT 522(TN/BK) is the wheel speed sensor LF -. Pin 26 CKT 514 (YE/RD) is the RF + and pin 27 CKT 516(YE/BK) is the RF -.

STROKER_T · June 23, 2009

Thanks Bruno,he's supposed to drop it off tomorrow afternoon,cant wait to see what the deal is... Posted Image

LARRY BRUDZYNSKI · June 23, 2009

Been reading and yes I can!!!! But doesn't the C1145 just pull a front ABS sensor code and could be either right or left sensor???? I know that the FORD scan tools can pull which one it is but could the scan tool be reading it wrong??? Or could they have had someone looking at the system or maybe a accident????

STROKER_T · June 24, 2009

Well Larry,I did get another code for the right front,wanna say it was for input ckt,after the left front was replaced the ABS light hasnt been on since...still waiting on him to bring it back,hope he doesnt have any issues(like a wreck).I learned a valuable lesson on this one,rest assured...

Jim Warman · June 26, 2009

Thanks for the ever so short insight Jim,always a true pleasure reading your antics...even though its reads as if your being a smart ass.

Just kidding Jim,especially after understanding how much good sense you make...had to read into it a bit...

Tony... I always come across sounding like a dink because I am, indeed, a dink. (Grade A,number 1, extra large - ooooh, yeah - ). However, when we consider what is at stake, even some of the little, inconsequential stuff can get severely in the way.

What we desparately need to remember is that while things mechanical are second nature to most of us, the vast majority of society are NOT machine people - in fact, they are people that can turn a simple hand tool into a dangerous weapon. These are the people that rely on us to keep them safe.... even when they ask "can you do it cheaper?" (Sure I can... what parts do you want me to leave out?).

My bedside manner is atrocious... but once you get past that,everyone will see I only have their best interests (and those of my chosen vocation) at heart.

Like Pavlovs dogs, too many of us are "programmed".... The moment a customer starts to waffle on price, many of us start to search for ways to fuck ourselves over... But...I digress. We can behave as professionals or we can be turds...