ABS over compensates on really gradual dry stopping?

maxg765 · #1 11-25-2008, 11:32 AM

Hello All,

I have an issue with my breaks. I assume something with the ABS.

Here are my symptoms.

During really gentle slowing on dry roads just before I come to a full stop the last few seconds, the ABS kicks in and this extends my stopping time and distance. And I mean very gradual gentle stopping. Its less apparent with hard or harder breaking.

Also, on occasion the ABS light will come on and stay on till I turn off the car and back on again. From my understanding all the discs, rotors and pads are like new and were checked back in March of 2008 by the same Subaru dealer that has always serviced this car since new and the car has only done some 500 miles since.

When the ABS light is on the problem is not there but this obviously means that the ABS is not functioning.

Any suggestions or ideas would be helpful as I don't know of any place to bring it but the dealer and they are expensive. I am also not technical and wont be able to connect any computers and read codes etc..

I am concerned as this will be my only driver for the next few months and in Montreal the winters are rough plus I have a baby that will be in the back seat from time to time. Safe stopping will be important and the ABS over compensating can cause me to slide into a car in front at a stop light etc......

I only just got the car. its a 97 which has been well cared for and has 46000 original miles on it. Its a US origin car and everything else appears to be in very good to excellent working order. The car has seen VERY little usage until this past week since Jan of 2008. Could something be sticking or a sensor be loose? The tires are very good, 225/50/16's of all the same brand and tread and properly inflated as well.

Thanks in advance for any help.

Max

legacyau · #2 11-25-2008, 02:59 PM

Are all the tyres the same size?

maxg765 · #3 11-25-2008, 03:09 PM

Quote:

Originally Posted by legacyau

Are all the tyres the same size?

woops, I should have put that.

Yes they are all 225/50/16 and of the same brand with at least 75 to 80% tread left. The front have the pressure at 33PSI and rear at 29PSI like the book and door suggest.

It is a 97 which originally came with the size of 215/55/16 but I was told by Subaru that it makes no diff to put the size that previous years came with being the 225/50/16 mentioned above. It was changed to save money and for no other reason they told me. The car was designed to have the 225 width.

Thanks

Max

odepaj · #4 11-25-2008, 08:49 PM

Try having the system bled, along with the ABS unit (in the factory specified manor).

It might not fix your problem, but it's always best to stick to the K.I.S.S. rule

(Keep it simple, stupid)

Hope that helps!

Dustin

Crazy_pilot · #5 11-25-2008, 09:23 PM

I would say most likely a cracked tone ring or faulty sensor.

maxg765 · #6 11-27-2008, 09:07 PM

Hello All,

For those who did not see my first post, I am having trouble with my ABS under all conditions (dry as well) during gradual gentle breaking at the point just before coming to a stop the ABS kicks in and extends stopping.

http://tinyurl.com/5gfcdu

So I checked out the code as per the link above. Someone please confirm if I am doing this correct. I drove, waited till the ABS light came on the dash. Pulled over and checked for the codes. It flashed red 5 times in repeated intervals. Thus if I read the page correct it should mean that I have trouble with:
“Faulty ABS Sensor” at “Left Front Wheel Speed”
Assuming I am correct can someone please advise me what part I should look at and order as a replacement?

Thanks in advance

Max

NikFu S. · #7 11-27-2008, 10:32 PM

$120-160 for a new "Front Lh Sensor Sub". That's all I can tell you. I've never replaced one.

svxistentialist · #8 11-28-2008, 04:33 AM

Hello Max. How are you getting on?

The procedure you used seems correct. I would have to presume your diagnosis is correct and the Left hand front wheel sensor assembly needs to be replaced.

Have you access to the workshop manual? There are 3 pages on stripping and replacing the sensors, etc.

If you don't have the manual I will scan the three pages for you. Let me know if you need this done.

There is one thing you should do before you order the part. If the tone wheel is cracked or damaged it could be causing a problem. As it is a mechanical part there is no way a code can show if it is broken.

Essentially you should follow the procedure and strip the LH wheel. If you see the tone wheel broken it might be wise to replace that first, then drive the car and see if your 5 code comes back.

If the 5 code does not come back at this point, then probably the sensor is OK.

However, my gut feel is your sensor is broken. If I was in your shoes I would strip it down first to get a look at the tone wheel. If the tone wheel is OK, order your new LH sensor.

Joe

maxg765 · #9 11-28-2008, 07:21 AM

Quote:

Originally Posted by svxistentialist

Hello Max. How are you getting on?

The procedure you used seems correct. I would have to presume your diagnosis is correct and the Left hand front wheel sensor assembly needs to be replaced.

Have you access to the workshop manual? There are 3 pages on stripping and replacing the sensors, etc.

If you don't have the manual I will scan the three pages for you. Let me know if you need this done.

There is one thing you should do before you order the part. If the tone wheel is cracked or damaged it could be causing a problem. As it is a mechanical part there is no way a code can show if it is broken.

Essentially you should follow the procedure and strip the LH wheel. If you see the tone wheel broken it might be wise to replace that first, then drive the car and see if your 5 code comes back.

If the 5 code does not come back at this point, then probably the sensor is OK.

However, my gut feel is your sensor is broken. If I was in your shoes I would strip it down first to get a look at the tone wheel. If the tone wheel is OK, order your new LH sensor.

Joe

Hello Joe,

All is well thank you. I have been driving the car for only a week now and I do enjoy it so far. I have not used it much as I just imported it some 11 days ago and still have not gone through all the hoops the Govt makes us go through to properly plate and insure the vehicles. Yesterday I did the Provincial mechanical inspection and it passed with no problems. Next week I have to do the Federal but before doing so I need to have daytime running lights 9I will glue the bottom of the headlight switch to the on position and just say that it was s equipped), french aid bag labels which it already has, functioning airbags which it has, KM's showing on the dash which it has but the miles is the outer larger readings but I was told they don't fuss anymore as long as you have both showing at all times, and finally the car needs to have child anchors which I have someone on here that has sent me a set. After all that I can go to get it plated. Should be all next week for the final process.

I do not have access to a shop manual. If you could email me those 3 pages that would be great. It unfortunately will not be I who will be doing the work as I do not poses the experience or tools/facilities to do so but I will go over it with my mechanic and be present when he opens it up. I do not know exactly what the tone wheel part is but if on those three pages I will review but I believe I understand the just of it (some physical part that can cause the sensor to vibrate or have a false reading due to being broken).

my email if easier is

................................
Also, thanks to NiKFu S, for the price estimate in the sensor.

I thank you in advance for your kind help.

Best regards

Max

svxistentialist · #10 11-28-2008, 08:14 AM

Quote:

Originally Posted by maxg765

Hello Joe,

All is well thank you. I have been driving the car for only a week now and I do enjoy it so far. I have not used it much as I just imported it some 11 days ago and still have not gone through all the hoops the Govt makes us go through to properly plate and insure the vehicles. Yesterday I did the Provincial mechanical inspection and it passed with no problems. Next week I have to do the Federal but before doing so I need to have daytime running lights 9I will glue the bottom of the headlight switch to the on position and just say that it was s equipped), french aid bag labels which it already has, functioning airbags which it has, KM's showing on the dash which it has but the miles is the outer larger readings but I was told they don't fuss anymore as long as you have both showing at all times, and finally the car needs to have child anchors which I have someone on here that has sent me a set. After all that I can go to get it plated. Should be all next week for the final process.

I do not have access to a shop manual. If you could email me those 3 pages that would be great. It unfortunately will not be I who will be doing the work as I do not poses the experience or tools/facilities to do so but I will go over it with my mechanic and be present when he opens it up. I do not know exactly what the tone wheel part is but if on those three pages I will review but I believe I understand the just of it (some physical part that can cause the sensor to vibrate or have a false reading due to being broken).

my email if easier is

................................
Also, thanks to NiKFu S, for the price estimate in the sensor.

I thank you in advance for your kind help.

Best regards

Max

Max

I'm delighted you are enjoying the car. I have a '92 myself with 40K miles on it. It drives very tight, a lovely machine to drive.

I will scan those pages for you later and send to your email address. I hope you don't mind my editing your post and removing the email address. We advise people to send addresses and phone numbers and in particular email addresses to other members by PM [private message] Once an email is up on a public post the spybots that scan the web all the time can copy your email and sell it to email marketers. You would be up to your neck in viagra offers and other rubbish spam in no time.

You are correct about the tone wheel. It is a ring that rotates with the hub, it has teeth on it. The sensor reads the tone wheel and sends the signal to the computer to estimate the speed of rotation of the wheel. If the tone wheel got physically broken the signal would be corrupt. The computer might interpret the corrupt signal from the sensor as a bad sensor.

If this was the case you could replace the sensor, and the computer would still see the corrupt signal because of the bad tone wheel and again post a code for a bad sensor, even though it is new. If the tone wheel looks OK and undamaged it is 99.99% likely that you need the sensor. If the tone wheel is broken or visibly damaged, replace that first, it could save you the $160 for the sensor.

I'll send you the scans later.

Joe