1999 Saab 9-5 SE ABS Lights

[shipleg]

I have the ABS lights on and could really use some advice. Car is a 1999 Saab 9-5 SE … 135k miles

After starting the car and the car going through its checks, there are no dash/warning lights on at all. When I start driving (either forward or reverse or rolling in neutral) and at 8 mph (according to my GPS) the ABS lights come on, including Brake, TCS and ! The speedo, tach, and other gauges work throughout. The control module has been checked good by BBA, the 4 wheel speed sensors are new, and the tone rings are clean. The #26 7.5 amp and #1 60 amp fuses, tire pressure, brake fluid and brake thickness are all good. I’ve checked the continuity and voltage on the front speed sensors – both check good. I tried disconnecting each speed sensor, one at a time, and each resulted in all the lights coming on. The are no codes on an OBD and unfortunately I don’t have a Tech II.

I looked through the forums and didn’t see a situation like mine. I have a state vehicle inspection coming up and would appreciate any advice.

[sgould]

Welcome!

I suspect a small crack in the toothed ring on one of the front axles.  This will increase the gap between two of the teeth enough to cause the ABS to activate.  It’s not a matter of cleanliness of the teeth.  You will need to look closely to see the crack.

The toothed rings - reluctors - can be obtained separately, but fitting a replacement constant velocity hub may be quicker, if the ring is cracked.

The speedometer will not be affected. That’s driven by signals from the rear wheel sensors.

[Audax]

I suspect a small crack in the toothed ring on one of the front axles.  This will increase the gap between two of the teeth enough to cause the ABS to activate.  It’s not a matter of cleanliness of the teeth.  You will need to look closely to see the crack.

I would agree with this, I've known the cracks to be very difficult to see so that until they're in your hand to inspect you can't see them.

[shipleg]

Thanks for the welcome and for the feedback.  I was hoping it didn't, but the evidence points to the reluctor ring(s).  Is there any way to test the rings while they're still on the car?

It looks like they don't make the CV axle for the early 9-5s any more.

Thanks,  Regards, Gary

[Audax]

Is there any way to test the rings while they're still on the car?

It looks like they don't make the CV axle for the early 9-5s any more.

I think that a Tech-II would give the speeds and show which was faulty, I can't remember now though as it's been over 10 years since I last used Tech-II. You should be able to get the reluctor rings though and get someone to fit them to an old CV joint.

[sgould]

You can see them with the wheel off.  If they are clean you should be able to spin the wheel and look carefully for a crack.  It may be signalled by some brighter rust. 

The broken ring should be easily removed.  A new one can be tapped on, maybe with the help of being warmed in an oven to expand it a touch.  You need to separate the driveshaft from the hub to get a new one on.  The rings are generally offered on the usual internet sites from about $5 upwards.  Just double check that you get. one with the correct number of teeth.

If you want an OE spec one, talk to  https://www.esaabparts.com/ The ship genuine parts from Saab/Orio, but they also use their own stuff.  They are based at the Saab Heritage Museum in South Dakota.  I met the guys at the Saab Museum in Sweden a couple of years ago and they are very friendly.

[shipleg]

Audax and Sgould - thanks for hanging with me and providing your advice.

Last night I had a chance to pull the front wheels and take another look at the reluctor rings.  Attached is a foto of a section of one of the rings ... both rings look like this all the way around.  I didn't detect any cracks, but as you mentioned they are hard to see and don't take much to set off the light.

Seems to me that if all my dash lights are off after starting the car and before moving, then the control module, 4 speed sensors, and all the wiring are good.  Otherwise, with any of those parts being faulty, the ABS/Brake/TCS lights would come on (stay on) after starting.  Do you think that is an accurate diagnosis? 

So, I think I am down to replacing the rings.  I would try to get a Tech II reading, but the shops charge over $100 for a reading and two rings from eSaabparts are only $70.  It would be great to find a member of a local Saab car club that has a Tech II, that would help me out.

BTW - that was a great story about meeting the esaabparts guys at the Saab Museum.

Thanks again for your inputs.  Regards, Gary

[sgould]

Hmm!

Those rings don't look very old. Mine were a bit corroded.  I'm now wondering if they have been replaced recently, which begs the question "Were the right ones fitted?" Ones with the correct number of teeth.  Do you know the history?

Audax and others have a lot more hands on experience than i do, so hopefully you will get a comment on my opinion.

[Audax]

That's a brand new ring, I also wonder if the wrong type have been fitted. I'm fairly certain that a failure at around 8mph was a wheel speed sensor issue. At this point I'd be counting the teeth on the rings. Of course it could be a rear sensor ring which I think was integrated into the wheel hub that is faulty.

Personally I would pay the money for Tech-II with someone who knows what they are doing next.

[sgould]

If you can rotate the wheel and check, the rings should have 29 teeth.

The esaab price is the official Saab price.  I would suggest that $70 is a bit high when you can get acceptable rings from eBay for around $5 each.  But Saab parts come with a guarantee, if fitted by a proper garage/shop.

[shipleg]

I am the original owner and no one else has touched the car except the dealer for the 65k timing belt service.  It's been an incredibly reliable car and still fun to drive.

Another test I did last night was to spin the front wheels (one at a time), with the wheel off the ground, the engine running, and the car in neutral.  I thought for sure I would get the lights ... but I didn't.  Maybe I didn't get them spinning as fast as I thought I did.

It feels like I am missing something basic about the operation of the ABS.

Thanks

[sgould]

I’m not 100% sure about this, and I’m away from my references, but I think that the ABS is inactive at slow speeds.

I’m still suspicious of those rings. They are far too clean and shiny for a car that’s over 20 years old.

[Audax]

I noted that you called them "tone rings" earlier, which is a terminology I was not familiar with for the reluctor rings. Did they say they were clean or had been replaced? I have known the rear ones to be faulty before hence why I'd get it on Tech-II.