ABS help

I assume dry is the same as cold? The board is coated with a clear flexible coating so it's hard to see them clearly. I'll re inspect them .

Ah, OK - best left alone then !

Well, as a electronics genius I'm very much a hopeless novice so I have no advice about repairing the module. However, I've had such a lot of help and advice from the folks on here, I'm more than keen to repay the privilege by offering some help I can do.

**broken link removed** may be helpful. Looking at the testimonials they seem to have a good name.

S

This is a Ford module that was faulty, If you expand the picture you will see Dry joints where the black dots on the board are. This is common on circuit boards in vehicles, just need resoldering.

Module masters said they cannot repair it.

I will re inspect mine for bad joints. Is dry the same as a cold joint?

Ok I have what I hope is needed for someone to help with my convertor.

I tired to get some better pictures of my module. I suppose if I find a bad joint scrape the clear rubbery coating off and re solder.

http://s17.photobucket.com/user/OLDARMY45/library/silversuperhupty/Build pics?sort=3&page=1

The sine wave from the diff looks like an inductor type pickup not a hall sensor. It looks like the module converts every 10 peaks of the sine wave to one positive & then a Negative pulse to drive the speedo.

This should do the conversion :-

Sim works with sensor signals down to 1mV at 1Hz, with or without a DC offset. R1/D1/D2 clip any excessive signals.
I've had to guess at the waveform timings, because they're obscured in your pic, so you may need to tweak C3/R5.

I'll see if I can get a more clear pic

Nice differentiated pulses there Alec, but I cannot help but think that the pulses shown by the OP are really a square wave viewed with a badly compensated scope probe.

Just my natural suspicion of such things, and, why would anyone deliberately design something which puts out pulses like that?

JimB

Ford makes some weird stuff for sure....

This is what I was told by a mechanic who posted an article troubleshooting this module.

"As I remember the signal that comes from the axle sensor is an analog signal and it is converted to a digital square wave signal before it is sent out"

JimB said:

I cannot help but think that the pulses shown by the OP are really a square wave viewed with a badly compensated scope probe.

Click to expand...

That may well be the case, Jim. A square-wave makes more sense for susequent processing by the speedo module.

The Extractor said:

the signal that comes from the axle sensor is an analog signal and it is converted to a digital square wave signal before it is sent out"

Click to expand...

Sent where?

I believe it goes to the PCM and GEM.

So should I go for it with that circuit design or do I need more testing to verify the patterns and timing ?

It could very well be a variable reluctance sensor: https://www.google.com/url?sa=t&rct...mEfhWGSaT23n89Q&bvm=bv.88198703,d.cWc&cad=rja

There are signal conditioning circuits designed especially for it.

LM1815 (Old)
https://www.google.com/url?sa=t&rct...JfjJpPM6MKjUXhw&bvm=bv.88198703,d.cWc&cad=rja

MAX9924-MAX9927
https://www.google.com/url?sa=t&rct...=NeNZ_5LosC0BsWXEjbOw2w&bvm=bv.88198703,d.cWc

Thanks for that info, however it is mostly way over my head. This is the pn spec'd for my truck
MOTORCRAFT Part # DY1123

I just found this info as well, this is a bunch of snippets of forum posts from the net regarding issues such as mine.
Each snippet is marked at the end with - end



Here's the description from the service manual.

"A variable sensor and toothed speed indicator ring used to determine wheel speed. As ring teeth pass by a reluctant sensor, a pulsing voltage signal is generated and sent to the ABS module. Voltage pulses are directly proportional to rotational wheel speed" -end


The module takes speed sensor data in the form of Volts AC from the rear diff speed sensor (often referred to as the VSS but is actually just a Speed Sensor) and the front wheel sensors in the hubs. These values are used to determine the speed of each of the corners and adjust braking appropriately.

The EHCU outputs a Vehicle Speed to the PCM called VSS. The VSS is used by Speedometer, Odometer, Cruise Control and other items and also is crucial to Transmission shifting. At least I believe so.


Rear Speed Sensor Data – Read VAC at pins 6-14. On Open or LS Diff, the rear may require spinning the “drive” wheel or drive line to force the tone ring to rotate.

VSS Data – Read VAC while the vehicle is in motion. Should be approx 1.25 VAC at 30 MPH.

-end

For F-Series and Excursion, the VSS signal is generated by Generic Electronic Module (GEM). The GEM generates VSS from a speed sensor on the rear axle.

On vehicles equipped with 4-Wheel Anti-lock Brake Systems (4WABS) , the vehicle speed signal is generated by the rear anti-lock brake sensor and sent to the 4WABS module. The 4WABS module sends the vehicle speed signal via circuit 679 (GY/BK) to all systems that require a vehicle speed signal input. Vehicles equipped with Rear Anti-lock Brakes (RABS) generate a vehicle speed signal from the rear axle speed sensor. The Generic Electronic Module (GEM) receives this signal (VSS_GEM) for internal use and then distributes it to the appropriate other users (i.e., the Powertrain Control Module [PCM] , speed control module, and speedometer). -end

As I understand it these little VSS units are just tiny passive pulse generators, which one industrial supplier calls "Analog Output Variable Reluctance Sensor -- Passive sensor, doesn't require external power source." It's just a little permanent magnet, probably surrounded by a little coil, mounted inside a snap-on or screw-on can.-end

What bugs me is that C135 goes to the Radio and the Windshield Wiper Motor and is in parallel. If this was a GM car, I'd say it could be Class II data. i.e. messages, not the actual signal. Later vehicles are adopting the CAN bus in general.

The signal from this sensor will be a sine wave as the sensor is a two wire pulse generator. You never said what year this truck is but I assume is is a 90ish type Ford pickup. You also never said what the reason was for the bypass? You have to keep in mind that this sensor works off speed and is obviously variable and must be syncd with the front wheel speed sensors. If you have removed the ABS module, not sure what you are trying to accomplish. Can you outline that for us?

KeepItSimpleStupid said:

What bugs me is that C135 goes to the Radio and the Windshield Wiper Motor and is in parallel. If this was a GM car, I'd say it could be Class II data. i.e. messages, not the actual signal. Later vehicles are adopting the CAN bus in general.

Click to expand...

The wipers and radio work fine. The year is 2000, f350 v10 automatice 4x4.

bwilliams60 said:

The signal from this sensor will be a sine wave as the sensor is a two wire pulse generator. You never said what year this truck is but I assume is is a 90ish type Ford pickup. You also never said what the reason was for the bypass? You have to keep in mind that this sensor works off speed and is obviously variable and must be syncd with the front wheel speed sensors. If you have removed the ABS module, not sure what you are trying to accomplish. Can you outline that for us?

Click to expand...

The year is 2000 f350 v10 automatice 4x4.

The reason is I cannot find a replacement part or a place to repair my module. It is an uncommon model as most of the trucks did come with 4 whl abs, mine is only 2 whl, or RABS. Im not trying to be cheap or save a buck. I would leave the module in if it wasnt broken and or I could find a replacement.

There are no front wheel speed sensors, it did not come with them from the factory as my truck is 2 whl abs.

I removed the ABS hydraulic unit that this ABS module controls when I modified it for off road duty as ABS is dangerous for offroad driving.
Also the "ABS" on this truck is not the same as on cars, really all that this system did was take away 65%or more of your brakes so you can maneuver but not really slow down, Im not ok with that. It does not pulse or anything like that.