intermittent ABS warning light 2000

knl25 · 02-07-2007, 08:21 AM

I decided to tackle my ABS warning light issue because it's been on and off intermittently since I bought it.

I first suspected bad wheel sensor(s) per many previous threads. I borrowed a scantool with the ABS diagnosis and found that all 4 wheel sensors are reading same speed value, but they indicate wheel speed of about half of the speedometer reading. Another thing I noticed was that the ABS main power relay output is "1bit" when the ABS warning light is OFF and is "0bit" when it is ON.

So it seems like the ABS power relay is bad. My alldata manual for this model says that the part number for the relay is FOAZ14N089A but it also says that "the ABS is not equipped with an external ABS Relay. According to wiring diagrams provided by Ford, the function of the ABS relay is incorporated into the ABS module". Does this mean that I have to replace the whole ABS module or HCU just because the relay is bad?

Has any of you encountered this issue? Any idea on why wheel speed is different than speedometer?

thanks for reading

phil-l · 02-08-2007, 05:58 AM

Sorry, I don't have further info. But I also have a 2000 Windstar - and the ABS light came on (for the first time) just the other day. I stopped and re-started the van - and the light went away; hasn't returned since.

But I'm concerned something in the system is marginal and will cause problems soon - so this thread is particularly timely for me, and I hope someone with specific experience chimes in soon.

One question: What diagnostic tool did you use to access the ABS system? I'm familiar with OBDII scanners, as well as older Ford ABS diagnostics that could be read using a jumper wire and voltmeter.

gbusby · 02-08-2007, 09:06 AM

my 2000 LX 3.8 has the ABS light on at times and I haven't been able to isolate the cause. Turning off the engine resets it and then it stays off for days. I would also like to know how you access the diag for wheel speed.

Watching this thread intently!!

opcorn:

Ed_Strong · 02-08-2007, 11:21 AM

Count me in too...!
I also have a 2000 LX 3.8 that has the ABS light on at times and I too haven't been able to isolate the cause. The ABS switch was leaking and replaced about six months ago, but the ABS light keeps coming on. Same thing as mentioned turning off the engine resets it and then it stays off for days. I too would like to know how you access the diagnostics for the wheel speed.

knl25 · 02-08-2007, 04:02 PM

I borrowed the scantool from my cousin who bought it from Autoenginuity with the Ford expanded package which allows you to access ABS diagnosis. My ABS light is OFF right after the engine starts up but would eventually be ON. Keep me posted if you guys decided to investigate the issue further.

phil-l · 02-08-2007, 04:51 PM

knl25 -

What do you know about the Autoenginuity scanner? I've seen their scanner kits on eBay (a module that goes to a PC USB port; sells for about $200), but - as you noted - it requires an expansion to read ABS codes (I didn't find price info on the expansions).

knl25 · 02-08-2007, 05:15 PM

My cousin bought it on ebay for $200 like you said and the expansion on autoenginuity.com website for about $150, which is basically a code they will email you to activate that function on the software. I don't have any experience with other scantools in fact this is the first time I use a scantool but think it works quite well for what it says. There are literally hundreds off sensor readings and functions you can track in real time. My problem is to interprete the data it gives to arrive at a correct diagnosis.

DRW1000 · 02-09-2007, 06:40 AM

Quote:

Originally Posted by knl25

My cousin bought it on ebay for $200 like you said and the expansion on autoenginuity.com website for about $150, which is basically a code they will email you to activate that function on the software. I don't have any experience with other scantools in fact this is the first time I use a scantool but think it works quite well for what it says. There are literally hundreds off sensor readings and functions you can track in real time. My problem is to interprete the data it gives to arrive at a correct diagnosis.

Is it possible that the 4 wheel speed sensors reading at 1/2 value is the result of a software bug rather than incorrect raw data?

Have allof you ensured that your fluid is topped up?

Before buying expensive tools go around to each sensor and disconnect the harness of the speed sensors at the wheels and check for continuity. My light was on for 2 years until I did this test and found an open circuit at one sensor. $50 bucks later and I have ABS. - needed it a couple of times since too.

DRW1000 · 02-09-2007, 06:40 AM

Quote:

Originally Posted by knl25

My cousin bought it on ebay for $200 like you said and the expansion on autoenginuity.com website for about $150, which is basically a code they will email you to activate that function on the software. I don't have any experience with other scantools in fact this is the first time I use a scantool but think it works quite well for what it says. There are literally hundreds off sensor readings and functions you can track in real time. My problem is to interprete the data it gives to arrive at a correct diagnosis.

Is it possible that the 4 wheel speed sensors reading at 1/2 value is the result of a software bug rather than incorrect raw data?

Have allof you ensured that your fluid is topped up?

Before buying expensive tools go around to each sensor and disconnect the harness of the speed sensors at the wheels and check for continuity. My light was on for 2 years until I did this test and found an open circuit at one sensor. $50 bucks later and I have ABS. - needed it a couple of times since too.

knl25 · 02-09-2007, 08:10 AM

It's certainly possible that the difference in speed is a software bug. Can you explain why the ABS relay state is ON when my ABS is OFF and vice versa? Is this an indication that the relay is bad? I checked the resistance on all wheel sensors and they were around 1.8-1.9 kohms. I don't know if the values are normal but they are surely not open circuit.

gbusby · 02-09-2007, 09:23 AM

i would have to look at a wiring diagram. But my first guess would tell me the relay is not bad. usually if a relay fails, it wont change states at all. If yours is changing, it's probably working. They may be utilizing a normally closed contact and opening it when the relay is "on" to disable the ABS if a problem is detected. (thats my first thought, still haven't gotten the diagrams for the ABS system.)

knl25 · 02-09-2007, 05:23 PM

Are you saying there is a safety mechanism that would switch off the relay if something goes wrong with the ABS system? I have alldatadiy.com subsription and can access the wiring diagrams but can't locate the relay. Maybe I don't know how to read these. If you can tell whether the relay should be off or on at certain state, I can try to post them somewhere.
Thanks!

knl25 · 02-11-2007, 12:13 PM

It turns out the difference in speed between wheel sensors and speedometer signal is due to the scaling in units and in fact its a bug in their software that has MPH and KPH switched.

I still have no clue on why my ABS warning light is on and not sure what to try next.

dragos69ca · 02-14-2007, 07:09 PM

I have this problem very often...it comes and goes. I know that the reading method for the sensor is the problem. Although my ABS is sometime activated even is not slippery...it's kind of an error in the computer...I wish to know from where is the problem........

Ed_Strong · 03-16-2007, 10:03 PM

been out of the loop for a whole month and came back rushing to check this thread to see if there was an answer or a solution to this pesky problem. Please guys don't let this thread die away.

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