abs light intermittent

Hello all, if I ground the proper pin in the aldl will the check engine light blink out a code showing problems in the abs system? When started brake warning lights go out as usual. Upon driving the yellow abs comes on until I shut the engine off. When restarted the abs light is usually off until I start driving again. I am thinking one of the cables that connect the wheel sensor is failing/failed. Probably one of the front because of the wheels turning left and right puts more wear on the cable. Does the teves system set a code that will tell me where the problem is? Left wheel sensor/cable, etc? Is it read by counting the flashes of the check engine light? Last where can I find a list of codes and the part they are indicating?

Thanks for reading this,

Best Regards

Richard.

Richard,

In the '90 FSM, there are eight pages beginning on page 5E1-1 that cover just about everything you need to know about the ABS diagnostics.

John F.

Richard, the short answer to your question is yes, by shorting the correct two pins in the ALDL it will blink out the ABS trouble codes. But the long answer is it probably won't be worth the time and effort to do so. Experience shows the codes obtained are notoriously misleading and confusing giving extraneous problems and calling out the wrong side of the car for cable issues.

You are probably correct in diagnosing this as early failure of a sensor cable most likely in the front. The easiest test for these cables is to measure the resistance across them. Should be around 1100 ohms. A better test is to measure the AC voltage produced by the sensor as the wheel is spun.

The fact the light goes off until you are driving most likely means the cable resistance is present at start up so it passes the start up testing, but one wheel is not producing the same voltage as the others when rolling down the road triggering the light.then. A break out box makes these measurements easier to preform, but is not necessary

A careful inspection of the condition of the insulation of the front cables will probably show which one it is, or that both of them are going.

Thanks everyone, for some reason I did not see the section in the fsm. I will do some measuring of the abs wires. It is going to be heavy rain and high winds for the next few days, then I will check it out.

Best regards

Richard

Hey Richard

Here is a rather informative, albeit long, thread from Nov 2010 on ABS WSS's (wheel speed sensors) and the journey that Kitskaboodle went through with forum help to get his ABS light to finally be happy and go out. Well worth the read to the end of the post.

http://forums.aaca.org/f116/pinout-box-troubleshooting-abs-system-290315.html

Thought it might be a good idea to show the locations of the Wheel Speed Sensor disconnects on a '90 Reatta.

Front Left: Located in corner of fender-well and firewall.

Front Left connector disconnected.

Right Front: Located on fender-well behind Coolant Reservoir.

Left Rear: Located along frame rail near muffler hanger.

Right Rear: Located along frame rail near muffler hanger.

Pic. showing terminals "A" and "H" jumped on ALDL.

What you see are the test probes from a multimeter inserted in the terminal slots.

The other ends of the test leads were cut off, wire stripped and wire nutted together.

They are not connected to a tester.

A paper clip, opened up to form a "U" shape works just as well for this purpose.

This is on a '90 Reatta. '88 and '89 use different terminals.

John F.

Edited July 7, 2014 by Machiner 55 (see edit history)

Good job John. That is how I test the leads to see if they have ohm resistance. I do that before reading codes. Also gives one an opportunity to do a visual inspection for cracks in the leads.

John, The photos that show the location of the ABS sensors are really helpful. Would you mind if I used them on ROJ?

Ron,

Not at all. In fact, they're already there.

Dave,

Excellent idea. Might be a good idea also to note here that when testing for resistance that the meter probes are connected to the female contacts of the plug (brass colored "eyes" on the face of the connector) that lead to the WSS and not the male ends that lead to the ECBM module located in the trunk.

John F.

Edited July 3, 2014 by Machiner 55 (see edit history)

I want to use the photos in a tutorial for testing the sensors at the connector If that is OK.

What is the range (the lowest and highest) resistance that would be considered acceptable when testing at the connector as shown in John's photo below? Is there any other test(s) that should be done while the connector is apart?

I would also like to include instructions for examining the sensor leads... like where they are prone to break etc. I saw no problems with mine when I replaced my struts but I really didn't know what to look for. If someone would give me instructions it would be appreciated. Photos of a bad lead would be helpful but not required for a tutorial.

Ron,

OK. I'm posting these shots of a WSS lead with the deteriorated insulation that allows water infiltration that is so common to the sensor leads. Oddly enough, the sensor resistance reading is within spec.

If I remember correctly, the spec. for these are 800 to 1400 ohms. On an auto-ranging digital meter, like those sold in The Reatta Store, a reading of 1400 ohms would show as 1.400 k-ohms (k = kilo which is 1000 so the decimal point is moved three places to the right on the k-ohm scale to be read as ohms.) (I hope I got that right. Please correct me if not.) As for any tests on the sensor lead, other than the resistance test and a visual inspection of the insulation, there are none that I'm aware of. Removal of the lead from the car consists of squeezing the connector shroud and pulling the two sections apart. Then following the wire to the hole in the body that the lead goes through, wetting the body of the grommet with soapy water and twisting the grommet a bit to allow the soapy water to get between it and the hole. The the grommet should easily pull/push right out. There are some ring like wire loom retainers that need to be opened and there are insulating grommets that need to be pulled from their brackets to free the lead from the body. Then remove the "Torx" head screw (T-30) from the sensor head mounted on the hub. Once the screw is removed, removing the sensor head from the wheel hub is a whole 'nother story.

Ron, I'll post the pics on the ROJ

Edited July 7, 2014 by Machiner 55 (see edit history)

Thanks for the photos. I think I have what I need to write a tutorial on testing the sensors. I will try to get it done soon.

There is an even more meaningful test of these leads that also tests the functionality of the sensor and reluctor gear. After you check the static resistance of the lead, switch the meter to AC volts and set on the lowest millivolt range. Raise that wheel off the ground and set the brake and tranny so the wheel will spin freely. Watch the meter while you spin the wheel. The voltage should register and increase as you spin the wheel faster until it peaks out about 450 mv or .45 volt. This is the signal that the EBCM is looking at while you are driving. However, it is more interested in the frequency of this signal than its voltage level.

A bad lead resistance will trip the yellow light from the get go, while if the resistance passes, but the AC signal is bad, it will trigger the yellow light on as you drive.

McR,

Good to know.

This link to the thread regarding Kit's WSS issues, provided by Dan G. is a really good one for understanding the diagnostic process.

It also shows the awesome support provided by Forum members here.

John F.

John, those pictures and all the information supplied by you and others are a tremendous help. Plus Ronnie your site is a huge time saver and lifesaver.

Thanks all

Richard

I'm going to try to make a long story short. (my wife says that feat is impossible)

One of the reasons I was taking these photos was that I was trying to get a semi-persistent ABS fault light on my '90 Reatta to stay off.

Some time ago, I pulled the codes from the ASDL. Got distracted for several months (easier to do than you might think) and lost the piece of paper with the codes. Somewhere in the meantime I'd replaced the two front WSS cables and repaired two rears with "Liquid Tape". Tried a few suggestions from the Forum posters. Did nis-anat. Once or twice I thought I'd fixed the issue but... the ABS lamp illuminated once again and stayed that way. So, yesterday I thought I'd give it another try. Before trying McR's suggestion of spinning each wheel and checking the voltage, I thought I'd pull the codes again just for grins.

But try as I might, after jumping "A" and "H" terminals on the ALDL and turning the ignition. key on, the Anti-lock lamp would just stay steady on. Crap!

After a while, during which I read through the FSM diagnostics regarding the ABS system, getting more confused and frustrated, I decided to take the car for a drive. Something in the text stated that the car needed to be driven to at least 20 MPH braked to a complete stop at least once and brought back up to at least 20 MPH. So I did this but, without realizing it, I forgot to disconnect the jumper. Damn! Gotta start all over again. Somewhere in all this confusion the Anti-lock lamp started to flash but quit when I attempted to read it while back in the garage. Damn, Damn!

What happened next is really unexplainable but, I can say with certainty, that this thing happens with me quite often. I can only guess that there a part of my mind that is working the problem that my conscious mind is completely unaware of. NO! you say.

Yes! I say.

Now, I don't know what possessed me to do this but, I popped the hood and grabbed the drop light and placed it next to the firewall where the relays for the ABS system are affixed. I disconnected them both from the wiring harness and swapped them.

I then turned the ignition key to the ON position and come to find that I now had both the Anti-Lock lamp as well as the Brake lamp on and wouldn't go out. Damn, Damn, Damn! I went out, down the street and did my 20 MPH/ full stop/ 20 MPH thing and back to the garage. Tried to read/reset the codes - failed, then drove the car again. This time when I applied the brake the pedal got stiff. Uh-oh! Drove back into the garage and managed to not hit anyone or anything. I turned the car off, sat a minute then turned the key to ON. It was eerily quiet for some reason. Then, I realized the reason for the quiet was that the pump wasn't running! Eureka!!

The dim bulb inside my head suddenly got quite bright. (well.. brighter than it was before anyway) I rushed to my spare parts turnstile, spun the lower bins until my spare relays came into view. I grabbed two used but (hopefully) good relays and swapped them into position on the firewall. Checked to make sure the cover was on the ALDL, turned the key to ON.

The accumulator pump started it's happy little song and continued until both the Brake and Anti-lock lamps both winked out!

I took the car out for the 20 MPH/Brake cycle then proceeded merrily to the round-a-bouts (traffic circles) for a test spin and all has been right with the world ever since. (at least as far as the brakes on my car are concerned, the Middle East is still on fire) NO more always-on Anti-Lock brake light for me. No Sir!

After switching the relays and generating this "new" problem, It occurred to me that I'd moved a bad "Main" relay to the "Pump" relay position. This is why the accumulator pump didn't kick on after the switch. It's been reported before on this Forum that a bad relay could be the cause of the pump not kicking on (the pressure switch is another). But, I can't recall (or maybe I did)

a post stating that a bad relay would be the cause of a persistent or intermittent Anti-Lock fault lamp being illuminated.

Maybe it has and I missed it or don't/can't remember it. If you posted it, I'm sorry for re-posting a fix that has already been covered. Maybe one could include a link to it in this thread. That would be good.

I guess, in a nutshell, if you have an Anti-Lock illuminated and you've checked to make sure you pump is working and your WSS are working and have the proper resistance and checked all the other things suggested, you may just want to consider the "Main" relay.

In this instance, on my 1990, the "Main" relay (the one closest to the drivers side) was at fault. When it was moved to the "Pump" relay's position (the one closest to the passenger side), the pump stopped working. This indicated that the "Main" relay was bad. Of special note, on a 1990 Reatta, there are only two relays mounted on the firewall whereas on an '88 and '89 there are three. (See photos below)

If it hasn't been done before, maybe someone with a more organized cerebral cortex could make up a "Short List" of common or typical failure items under the headings of:

1.) Persistent or intermittent Anti-Lock Fault lamp illuminated. Check:

A.)

B.)

etc.

2.) Persistent or intermittent Brake Fault lamp illuminated. Check:

A.)

B.)

etc.

Errata:

A note regarding the "Round-a-bouts". Our Mayor, in his infinite wisdom, has decided that since no one was stopping at intersections anyway, anytime work is to be performed on an intersection, it shall be turned into a traffic circle. So.

if you ever happen to venture into the "Vale of Paradise" beware the round-a-bouts. They're everywhere!

One more thing... remember at the start of this discourse, I mentioned what my wife has to say about me keeping a story short.

I think she may be on to something. But, as I would say to her... "Just think how long it would be if I didn't keep it short."

John F.

Edited July 25, 2014 by Machiner 55 (see edit history)

great post, John!!!:cool::cool::cool:

looks like a first draft for a "tutorial" on ROJ.

Great job John and thanks for the info :-D

great post, John!!!:cool::cool::cool:

looks like a first draft for a "tutorial" on ROJ.

I intend to do a tutorial on troubleshooting the ABS. I've not forgotten about it. Family matters are taking up quite a bit of my time right now. John has done a good job outlining what he did and there have been some good photos posted about the ABS sensor leads as well. I'll try to get on it soon.

It would be helpful if someone with more knowledge than me would proof read this tutorial for me and give me feedback on mistakes or other problems with it you might see. I haven't had much experience with troubleshooting the ABS sensors so I could have some parts of the tutorial wrong. If so please let me know so I can correct it. Thanks

Wheel Sensor Troubleshooting

That's a good write up Ronnie.

If I can make a few suggestions, I would add a picture of a "good" sensor lead, one with the aluminum cap on the sensor barrel end. The other would be to check the relays on the fire wall as maybe a first step. Your point is well taken about starting with the front leads. And finally while I am not sure it was on purpose, but I think that if one has a intermittent abs light issue [or even a permanent one] it is not always a requirement to check the ALDL for codes. We all know that the most likely reason for a ABS light issue is the ABS leads the front ones being more likely.

And maybe as a followup another reminder about flushing your brake fluid and how it is important to the overall upkeep of the Teves brake system.

Thanks for your reply Dave.

That's a good write up Ronnie.

Thanks Dave.

If I can make a few suggestions, I would add a picture of a "good" sensor lead, one with the aluminum cap on the sensor barrel end.

I don't have a photo of a good sensor.

The other would be to check the relays on the fire wall as maybe a first step. Your point is well taken about starting with the front leads. And finally while I am not sure it was on purpose, but I think that if one has a intermittent abs light issue [or even a permanent one] it is not always a requirement to check the ALDL for codes. We all know that the most likely reason for a ABS light issue is the ABS leads the front ones being more likely.

And maybe as a followup another reminder about flushing your brake fluid and how it is important to the overall upkeep of the Teves brake system.

Actually the purpose I had in mind for this tutorial was just to list the instructions for testing the sensor leads. I was going to cover reasons for the light being on and how to troubleshoot it in a separate tutorial.