C1155 front left abs sensor fault

[Turdle]

Fighting this code for a while. Tried used sensor, no go. Replaced hub with new sensor, both sides, left front code came back.

Some discussion mentions forscan confusion between front sensors, so for giggles I disconnected right abs sensor and code C1145 added itself in, so we answered that.

Next I tried plugging in 2 other sensors , C1155 still present. I jumped bad sensor to right connector, no 1145 so left sensor verified good.

I guess now voltages need checked. Where would test points be please?

 

[J_C]

Left front. What year did Ford change from sending the signal to the ABS control module attached to the pump motor, and send it elsewhere to (?) ??


Anyway once that is known, measure for low resistance between the sensor connector and the elsewhere module connector, and that neither are shorted to ground, workshop manual stated something like at least 10K ohms. You can also spin the wheel and see if it's producing a low voltage... I think AC, but I'd try on DC as well. Compare to the same measurement at the speed sensor itself and/or to the other front wheel.


This pic is only relevant to my '98 and until they changed it. '00 IDK.

 

[J_C]

The workshop manual I'm looking at only goes to '99.

It states the signal goes to the 60 pin EEC-IV breakout box. Edit: That is only for test purposes, the breakout box is a shop diagnostic tool, not on the vehicle. /edit

PDF printout of that section attached. Relevant portion starts on pg 11.

 

[Turdle]

Well, I tested across the truck connector pins and see an open circuit.

 

[J_C]

That might be it! Between which pins? Does it send the signal to the ABS controller on the ABS pump motor on an '00?

I had a brain fart and didn't stop to realize that the EEC-IV breakout box is a shop tool, not equipment on the vehicle.

 

[Turdle]

That might be it! Between which pins? Does it send the signal to the ABS controller on the ABS pump motor on an '00?

I had a brain fart and didn't stop to realize that the EEC-IV breakout box is a shop tool, not equipment on the vehicle.

Thanks. Looks like loom stripping is in my future. It appears the sensor wiring returns to the abs module.

Need to step away from this for a minute. But we'll be back shortly.

 

[J_C]

I wouldn't tear open a loom that age if I could avoid it, I mean to find the faulty area, would just get enough access to cut the wire at both ends and string a new one.

 

[410Fortune]

looks like your getting it sorted!!

 

[Pete Deering]

I wouldn't tear open a loom that age if I could avoid it, I mean to find the faulty area, would just get enough access to cut the wire at both ends and string a new one.

They make harness tape. Amazon sell it.

 

[J_C]

^ My concern is disturbing old brittle wires. Don't want to try to tape them up from insulation failure or have to replace/repair more wires than necessary.

 

[Pete Deering]

^ My concern is disturbing old brittle wires. Don't want to try to tape them up from insulation failure or have to replace/repair more wires than necessary.

Sometime you have too. I open older wiring harness. If the wires are brittle sooner or later you will be repair them.
That why they call it the wiggle test.
You can buy 25 foot spool of wire at homedepot, and with a Sharpie paint pen( make a replacement wire the same color), replace the bad wire. If smaller length,
Harbor freight sell waterproof butt connector. the bad wire is probably near the wheel. Check the entire length for damage.
Home depot sells liquid tape, you can uses for wire insulation repair.
Also Amazon sells roll of heat shrink tape.

 

[Turdle]

Well, hnmm.

Wiring to abs module is fine. No amount of wiggling or stretching changed the meter reading on both wires showing zero ohms.coulndt get chirper to even crackle.
However, plugged into module still have what looks like infinite resistance. Open circuit.
Also, the right front circuit measured almost 200k ohms.


This is not good at all. Umm?

 

[Pete Deering]

Well, hnmm.

Wiring to abs module is fine. No amount of wiggling or stretching changed the meter reading on both wires showing zero ohms.coulndt get chirper to even crackle.
However, plugged into module still have what looks like infinite resistance. Open circuit.
Also, the right front circuit measured almost 200k ohms.


This is not good at all. Umm?

Some you have one broken wire.LH front wheel dies are 521 tan/Orange pin 24
And 522 tan/ black pin 25.
Did disconnect both connectors to see if there is corrosion built up at the connectors?
That fender is a corrosive area.
Try using your ohm meter and and see which wire is broken. Connect the black lead too a good ground and take the red lead and probe the speed sensor connector too see, what wire is broken.
Run a new wire from A. to B.

 

[Turdle]

Some you have one broken wire.LH front wheel dies are 521 tan/Orange pin 24
And 522 tan/ black pin 25.
Did disconnect both connectors to see if there is corrosion built up at the connectors?
That fender is a corrosive area.
Try using your ohm meter and and see which wire is broken. Connect the black lead too a good ground and take the red lead and probe the speed sensor connector too see, what wire is broken.
Run a new wire from A. to B.

Thanks, but please re read my post. wires from sensor to module are fine.
Zero ohms from sensor connector to abs connector on both wires.
Also, it's pin 17 and 18 on the abs connector. Just like post 2 in this thread
To recap. Wires good.

Infinite resistance across lf sensor connector
200 k ohms across rf sensor connector.


Abs module toasted it seems

 

[J_C]

This is not making sense to me. If the wire from the module connector to the ABS sensor connector reads zero ohms, on both wires, then measure the resistance of the sensor itself on its pigtail connector. Should be roughly 420ohms.

If the sensor itself is reading open circuit, the sensor is bad. If the sensor reads correctly, and plugged in you do not also get around 420 ohms at the ABS module connector, either a wire is shorted to ground, or one sensor wire to the other, or the connectors are not making good contact, or you have the wrong pins on the ABS module connector.

I did come across a wiring diagram that shows different pins on the ABS module, not sure what's up with that, might be related changes made on different model years:

 

[Turdle]

Ok, I will check for 420 ohms across pins 17-18 ( yes those are correct ) of the abs module connector, with sensor connected to it's socket. Results shortly.
Pins 17 and 18 are where I had continuity to each proper color wire to sensor connector, and lost it when I disconnected from sensor connector, so, yeah.

However, it won't explain 200 k ohms on the right abs connector and infinite on left abs connector at bumper, sensor disconnected, connector at module connected


Edit edit

 

[Turdle]

418 ohms across pins 17-18 of abs module connector

 

[Turdle]

Right sensor, pins 3-4

Left problem side sensor, also ok

 

[Turdle]

Ok, kinda oops.


With module re connected, I disconnected and sensor to read resistance across wiring to module.
My oops is a did not reverse my leads when checking earlier, resulting in mis communication on my part.

Ok, left side from connector to module is 167 k ohms one way, infinite when I reverse leads

Right side 185 k ohms
Infinite when leads reversed.

Reading a diode which is now a good thing.


In earlier hub- connector thread I wondered if polarity might be an iseue, low and behold, the diagram calls the lines low and high.

Next , I am switching polarity of the driver side abs sensor at the connector where I pinned them earlier. I don't expect it to fix though.

 

[Turdle]

Switching polarity kept me busy for a bit, threw some country ribs on the smoker, got out the forscan and no fixy