ABS Light coming on (1999 Pontiac Sunfire)

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

I know this a long shot. But there seems to be alot of mechanically inclined people on this site...

The warning light for my ABS keeps coming on. It was sporatic at first, now it is constant. In the begining when it would come on I would turn the car off then start it again and it would go away. This no longer works and I think some thing is wrong. I've checked the fluid levels, giggled sensors wires on the top part of the master cylinder. Nothing doing...

I am wondering if anyone out there has any ideas on what I can do to avoid taking it into a shop.

Thanks in advance!

bluefish86 · Posted: Jan 27, 2003 6:11 pm Post subject:

The exact same thing happened to an older pontiac I had, and we brought it in to the dealer and it turned out to be something wrong with the computer sensors that make the brakes anti-lock.

heliboy911 · Guest

I would test the ABS on a slick road. If they don't work get it checked out. If they do then a sensor is most likely messed up.

ohsix · Posted: Jan 27, 2003 7:51 pm Post subject:

sometimes brake dust can build up on the ABS sensor causing it to trip the warning light and sometimes will even make your ABS quit working causing the wheels to lock up under hard braking. you might try pulling off the front tires and cleaning up your brake calipers good with brake parts cleaner. be sure and remove the calipers from the rotor and clean behind the pads. you might even want to go ahead and replace your brake pads if they need it cause you've already got it all apart.

hope this helps.

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

That's some good advice...Is taking the caliper off hard? I like to think I am fairly inclined to do stuff like this. But from day one I kinda said to myself I wouldn't mess around with my brakes (Kinda dangerous). There was a squel coming from one brake, could this have anything to do with your theory?

Thanks!

skobi1 · Addict Joined: 15 Jan 2003 Posts: 639 City: eugene, or

moisture in the fluid can cause the same thing as well, pray its only a sensor. if it is moisture that will normally take out the hydraulic control unit, those get spendy.

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

I agree with those that claim the speed sensors are the culprit. The speed sensors tell the ABS controller how fast each wheel is spinning, if one of them is operating incorrectly, the controller gets a message that the wheels are turning at different speeds all the time. Sometimes this happens in normal operation if your car is slipping, etc... and the light will reset after you drive awhile or turn the car off, which is probably why that would solve it in the beginning. I would take wes's advice and start by cleaning it up. If you have a sound coming from one of the brakes, your pads may need replacement. Brakes are pretty easy to work on, especially disc brakes. If your new to it, do one side at a time so you'll have the other side for reference.

I have access to the trouble codes, so if you can read them with a scan tool I can tell you what the problem is. There are about 50 associated with the ABS light, if it is a speed sensor this code would reveal which wheel.

Nick
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OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

If after you clean up everything it still doesn't work, here is the procedure for removing a speed sensor, so you'll know what you'd be getting into.

To change the speed sensor you don't have to remove the caliper or even the wheel, though I would take the wheel off so that it is easier to get to. The speed sensor is held on with 2 Torx screws and is on the backside. It should have a wire harness coming of it. If the sensor doesn't slide easily out of the knuckle, remove the brake rotor (you do have to take the caliper off to remove the rotor) and use a punch to push it from the other side. If the locating pin breaks off, you'll also have to remove the rotor and push the locating pin out, clean this hole out but do not enlarge it.

Nick
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Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

I think I will give it a try, it's high time I learned about brakes! I guess I got myself a project for the weekend! Thanks for the advice...

marcg · Addict Joined: 16 Jan 2003 Posts: 944 City: Salt Lake City

Sell the Ponticrap and get a Toyota.
Laughing

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

We have a brand new Toyota sequoia. Our families first non-domestic vehicle, and probably our last. It has been in the shop more in it's 7 month existence than my pontiac has been in the 3 years i've had it. For what I put that car through, it has more than stood up to my abbuse. In my opinion...for what I paid for it, it's been a great car...Nothing special but a great car!

I'm not denying toyota making a quality car...but when you pay $55,000+ CAD I expected something more.

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

So I took some time this weekend to try to fix my car. I took off all the wheels, cleaned all the speed sensors, checked wiring ect. Checked all the fuses too. Then went for a drive...the light went off, and I was thinking great I fixed it. Now this morning the light is back on again? Think I am best to just take it in? I think something must be malfuctioning.

Nick, you mentioned reading the code...how do I do that? Do I need a scan tool?

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

Yes, if you get a scan tool you can read the DTC (diagnostic trouble code). This will be extremely helpful, especially if the problem is a speed sensor.

Here in MI a auto parts store called Murray's rents them out for free. You have to put a deposit on them that is refunded when you take the scanner back. Autozone will read the codes for free as well. Chances are that a local autoparts store will have a way for you to read the codes for free. I think they can tell you what the codes means as well, but if not I have the service manual. I guessing you'll get one these codes:

DTC C1221 LF wheel speed sensor input signal is 0
DTC C1222 RF wheel speed sensor input signal is 0
DTC C1223 LR wheel speed sensor input signal is 0
DTC C1224 RR wheel speed sensor input signal is 0

A description of the code is as follows:

The code will be set if the input signal is 0 and the speed of the vehicle is over 5 MPH, the code will depend on which wheel is messed up. Once the code is set the ABS light will come on and the ABS is disabled. The code will clear if you clear it with the tool or after 100 drive cycles with it working right. A drive cycle is starting the car, driving over 10 MPH and turning the ignition off. The service manual recommends checking the wires, plug, and harness first and then checking/replacing the speed sensor.

I've used them several times and actually just used one on a friends 2000 Pontiac Sunfire that I got from Murrays. It's pretty cool, it will tell you the error code or codes that are turning on that light. It will also tell you the engine RPM, coolant Temp. air temp, intake air pressure, etc...

Nick
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Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

Otto,

I got my car car diagnosed yesterday, it turns out to be a faulty speed sensor. Drivers side front wheel. So I am going to get my hands on new speed sensor today and swap it out. You mentioned how to change one out earlier in this post, but when I had the wheels off I tried taking one off. There was only one screw, but it is fastened in two places. Once I remove the one screw do I just pry the speed sensor off? Is is like a snap in type thing? Need some advice so I don't wreck something. I would like to do it without removing the caliper and rotor and what not if possible!

Thanks, you've been a big help!

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

Below are the steps. It does look like there is just one screw, the picture kind of made it look like there was two. Did you just get the code or did they do everything for you? Eitherway, keep in mind the problem could be with the wires connecting the sensor to the electronic brake control module. Also, after you fix it the light won't go out right away. The service manual claims that the only way to clear it is with a scan tool or after 100 drive cycles, each drive cycle being starting, going over 10 MPH, and turning the ignition off. It says disconnecting the battery won't clear it.

To take it off:

Disconnect the front wheel speed sensor electrical connector.

Remove the retaining bolt.

If the sensor locating pin breaks off and remains in the knuckle during removal, proceed as follows:

Remove the brake rotor and remove broken pin using a blunt punch.

Clean the hole using sand paper wrapped around a screwdriver or other suitable tool. Never attempt to enlarge the hole.

Remove the front wheel speed sensor. If the sensor will not slide out of the knuckle, remove the brake rotor and use a blunt punch or equivalent tool in order to push the sensor from the back side of the knuckle.

Putting the new one on

Install the front wheel speed sensor to the steering knuckle

Install the retaining bolt.

Tighten the Torx? screws to 12 N?m (107 lb in).

Connect the front wheel speed sensor electrical connector.

Clear the DTC code or wait for the light to go out.
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Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

Otto,

I checked the wiring as far back as I could. Everything seems to be in order.

I took the speed sensor off...without busting the locator pin!

I just got the code off them. They told me the drivers side ABS speed sensor isn't working. So I am trying to find a cheap one. GM want $148!!! I said no way! Hopefully I will find a used one or an after market part. You sure know your stuff though...are you a mechanic?

How come my light would go off then come back on sometimes? If it takes 100 cycles wouldn't the light stay on? Or does it mean the system is working, just the light isn't on but the code remains?

Thanks for your help dude, I owe you one!

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

I'm thinking your right and that the 100 cycles is just required to clear the code out of memory and that the light will turn off before then indicating everything is working. I can't find anything about what has to happen for the light to go off for a sunfire, most likely because the code is usually cleared using the scan tool which will definitely turn the light off. On my truck the light will go out after going over 8 MPH with everything working right.

I'm not a mechanic but a mechanical engineer that loves working on cars/motorcycles/boats. I grew up helping my Dad work on cars and once I turned 16 I've worked on my own cars and friends since then. I like doing the work my self mainly because I know it's done right, not to mention all the $$ you save. I enjoy doing all the normal stuff, oil change, spark plugs, brakes, etc... The most involved thing I've ever done was probably changing the timing belt and water pump on a Mitsubishi 3000GT, though I've also done clutches, and got to take a engine completely apart to show high school students all the parts.

Let me know how it turns out,
Nick
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Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

Otto,

I got my new speed sensor today, hooked it up...and guess what...IT ACTUALLY WORKED! Good to get that back working, we just got 8 inches of snow! Thank you very much for your help, I'm sure I saved some money doing it myself!

Thanks Again,

Geoff

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

Glad to help!

Nick
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Coach_Mike · Newbie Joined: 24 Jan 2003 Posts: 10 City: Chicago Area

Hi guys,

Sorry to keep this going but thought you might be able to help me out with my situation as well. I have a '95 Firebird which also has the ABS Inop light on constantly. Been driving me nuts for quite a while but brakes work normal. Maybe it's just a sensor also. How did you get the code information? Where did you get the replacement sensor and how much did it eventually cost? Confused

Thanks in advance,

Mike

Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

I got the code read by a local brake shop cost $35.00 Canadian. I bought the part for $115.00 Canadian, I kinda got a deal through a guy at work. GM wanted $149.00 Canadian. I can't find an after market part for it, I looked high and low...maybe in the states you might have more luck.

My light is still coming on, it was working for awhile. I am really frustrated now. It could just be that I need to get the code erased from the cars computer....But when I start my car sometimes the light turns off....but once I start moving a bit the light comes on and my ABS is disabled. Most often it is on, and I have no ABS. I think I might have to take it in....I sure hope the sensor was defective....otherwise I just dropped $150 on nothing. BEH I say....Good luck on your project...I'll let you know how mine goes, if you wait a little while I will post again and maybe save you some trouble....

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

Sorry the problem is back Geoff, only thing I can think of is maybe they interpretted the code wrong, if you can get the actual code they read I can check it. For a problem like this the service manual says to first check the wires, then check the speed sensor, and then the electronic brake control module. I'd also check the "teeth" like things I've circle in red, make sure they are clean and in tact. This is how the speed from the wheel is read. Also, if you have access to a volt-meter you can measure some other things. If you measure the resistance of the speed sensor it should be 1530-1870 ohms. Clearing the code may help as well, maybe the place that read it will clear it for free. If you have them clear it, get the actual code before then.

Mike,

Here in MI a auto parts store called Murray's rents codescanners for free. You have to put a deposit on them that is refunded when you take the scanner back. Autozone will read the codes for free as well. I think both stores are around Chicago too. If you get the code I can tell you what it means.

Nick
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Geoff Standish · Addict Joined: 13 Jan 2003 Posts: 843 City: Calgary

How do I check the electronic brake control module? I am starting to think it might be something like that...When I start it up the light is off, then once I go a certain speed I think it performs a test, I can hear the ABS come on for a second...then the light comes on and then system is disabled.

Is there anyway I can check that the wire to the speed sensor is indeed good? Like a voltage tester? Test light...etc.

I will check the teeth on the drive axle too.

I don't understand how the problem was fixed when I changed the speed sensor, but didn't last more than a day.

I'll try to fix it again after the weekend....

OttoNP · Addict Joined: 13 Jan 2003 Posts: 848 City: MI

There is a DTC for the electronic brake control module. The other way is to use the "fancy" code scanner that lets you read what speed each wheel is sending in real time. If you have this you can see if the sensor is indeed sending the wrong speed, if it is sending the right speed and the ABS sensor thinks its a problem, then the electronic brake control module is bad. You probably can't do this though...If you know someone else with a sunfire you could put your electronic brake control module in their car and see how it works.

The best thing I can think of is to get the code read again, there's always a chance it is something else. Also, reset the codes after you get them read to see if they come on again.

Sorry I can't help more,
Nick
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Coach_Mike · Newbie Joined: 24 Jan 2003 Posts: 10 City: Chicago Area

Thanks Guys,

I don't know how soon I'll get around to looking at this, but I'll certainly have some starting points. Much appreciated advice. Very Happy

Mike

Doug · Posted: Feb 17, 2003 3:21 am Post subject:

Geoff, any luck with the ABS? Now that I'm re-registered maybe I can be of assistance. I'm guessing you have a Bosch or possibly a Tevis ABS system. I presently work for TRW automotive, the division that does ABS, TC, and VSC. These are the big three in the brake industry. Let me know how it goes. Razz