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ABS Dashboard Light - 94 GEO PRIZM


sleepyfloyd's Avatar
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10-21-03, 08:35 PM   #1  
sleepyfloyd
ABS Dashboard Light - 94 GEO PRIZM

the Yellow ABS light on my wife's dashboard is on.. its been on for quite some time now.. it doesnt affect normal braking, but I'd like to troubleshoot it, to figure out what the problem is, and how do I fix it?

Its not the normal blue diagnostic ABS light that comes on after I start the car.. its a yellow one.. Sometimes it goes out right after I start it, then comes on immediately after putting it in gear and driving.

Are there any recommendations on where to start? I've seen the ABS Control Module on sale at Partsamerica.com for like $150 (after core charge).. should I just pull the control module and replace it, or is there something else I can check?

thanks,

sleepy floyd

 
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10-21-03, 10:11 PM   #2  
mike from nj
there's a lot of other things you can check, like the code that is stored in the system that is causing the light.

the procedure to do that is probably in a book somewhere at your library, definitely in a service manual.

if i knew any more, i'd tell ya.

 
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10-22-03, 05:18 AM   #3  
sleepyfloyd
Originally posted by mike from nj
there's a lot of other things you can check, like the code that is stored in the system that is causing the light.

the procedure to do that is probably in a book somewhere at your library, definitely in a service manual.

if i knew any more, i'd tell ya.
I looked in the Chilton's at my Library but didnt see anything. dont have the shop manual.... Do I need a special reader to read the codes? I have access to an OBD II reader, but I don't think it will work, since I thought it was for 1996 and later cars... is there a different one for earlier cars?

 
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10-22-03, 06:05 AM   #4  
Joe_F
You'll need the proper scanner and service information to service this.

Up the bones and get the GM shop manual---you can't fix this with half arsed information. ABS and brakes are not something to gamble with, for your own safety and the intregrity of the vehicle.

 
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10-22-03, 07:22 AM   #5  
sleepyfloyd
Originally posted by Joe_F
You'll need the proper scanner and service information to service this.

Up the bones and get the GM shop manual---you can't fix this with half arsed information. ABS and brakes are not something to gamble with, for your own safety and the intregrity of the vehicle.
I hear ya.... but trying to decide if its worth it to buy the manual and the tool, and then the part on top of it! Its probably cheaper to just to take it to a repair shop and have it done..

Especially since I can't even seem to figure out where to buy the scan tool, or even which one to buy for a 1994 Geo Prizm...

-sleepy floyd

 
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10-22-03, 07:25 AM   #6  
Joe_F
If you do your own work on your vehicles, the shop manual will pay for itself the first time you use it---even if you only learn more about what might go wrong.

As I have said in many posts here, I have gotten them for as little as $15 on Ebay for a GM manual. A Chilton will cost you that.

Gotta pay if you wanna play .

 
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10-22-03, 07:29 AM   #7  
History dictates that you are going to find a wheel speed sensor in need of replacement.

 
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10-22-03, 07:47 AM   #8  
sleepyfloyd
hmm... if thats a good starting point, how difficult are they to inspect and replace? and is there a way to tell which one is bad? short of getting a diagnostic tool, which I still havent been able to find where to buy one anyway...

I just checked and found that each wheel has a different part number. and they range in price from $130 to $145 a piece...

dang....

-sleepyfloyd

 
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10-22-03, 08:28 AM   #9  
yeah, you could check the resistance through all four sensors.
Find the connectors to each sensor( they all have a pigtail that disappears into the body, not too bad to find). Run an ohmmeter through all four. compare readings side to side. One will be out of whack. This can be done with out a scan too, nor knowing what code it is.

 
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10-22-03, 08:36 AM   #10  
sleepyfloyd
cool... i'll take a look at it tonight to see if I can figure out where they are and how to access them.

by the way, how do they work? Are they magnetic? I'm familiar with magnetic speed sensors that count the gear teeth on a gearbox, is there a marker or a pick up on the wheel that it senses?

-sleepy floyd

 
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10-22-03, 09:05 AM   #11  
YES A reluctor wheel passes by a magnet with windings in them, same idea about what you are talking about.

 
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10-25-03, 10:25 AM   #12  
sleepyfloyd
ok.. i finally got a chance to look at the wheel speed sensors.. well.. 2 of them anyway..

I could only get to the front 2 because the electrical connnectors for the rear ones are up inside the body, and I cant figure out how to get behind the rear wheel well flashing without using some sort of cutting tool.. The wheel well flashing for the front 2 came out with a few bolts.. I dont know why the connectors cant be placed in a more accessible location...

okay.. enough of that.. the ohm meter check on the front 2 gave me some interesting results..

The front driver side resistance seemed to oscillate.. anywhere from 30 ohms to 150 ohms..

The front passenger side resistance was 0, which means its an open circuit.. so.. I'm pretty sure thats the bad one...

whaddya think, bigguy05641?

 
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10-25-03, 12:37 PM   #13  
Well you would be looking for the readings to be the same from side to side, but neither of your readings sound normal. A reading of 0 indicates a short, and the readings on the other side sound kinda odd also. The meter should stay steady, I am not sure the spec, but probably 1000-1500 ohms probably. What scale did you have the ohm meter on? And we are connecting the ohmmeter to the two abs sensor harness leads right? The two wires that go to the sensor, those are the ones to be checking.
I think you are onto something, but recheck the readings, and take note of what scale that you have the meter set to....

 
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10-25-03, 01:10 PM   #14  
The rear sensors are accessed by removing the lower and upper rear seat.

Big is right the spec is about 1000 ohms. Don't move the wheel when taking the readings.

They are somewhat APIA to change. Usually rust in and the sensor breaks off. If so, easiest way is to break if off, pull out as much of the windings. Then us a small butane torch and heat the sensor. The outside of the sensor has a plastic sleeve that will melt and you can remove the sensor.

Clean the hole with a wire brush, best on the end of a drill or die grinder.

Larry

 
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10-25-03, 02:28 PM   #15  
sleepyfloyd
i checked the scale when I did it.. it went as high as 400 ohms.. but never to 1000.. I moved the scale around from Ohms. to Kilo-ohms and Mega-ohms.. but didnt get anything up there..

as far as rock-steady.. it might have something to do with me lying on my back under the wheel well.. trying to hold onto both probes and not sure if I'm getting good contact.. however.. the sensor that read 0 Ohms (open circuit), I couldnt get any reading at all.

Toyotaman -
I figured the rear connectors were under the seat too.. just from where the wires penetrated the body.. do you have any hints on how to get the seats out?

sleepy floyd

 
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10-25-03, 03:17 PM   #16  
Just pull up on the front of the bottom seat. After removing the bottom you should see bolts (usually 2) holding the upper. The seat back usually slides up to remove.

Larry

 
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10-27-03, 07:22 AM   #17  
I am wondering if the sensor that u are getting the reading of `0', is actually 'out-of-limits', which would indicate an open. Is it the same reading as when the leads to the meter are not connected to anything? If so, that sensor is definately the bad one.....
Toyotaman, I like your idea of heating the sensor up after pulling all the windings out. I usually go in with a die grinder to clean out the remaining bits of sensor housing......

 
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10-27-03, 07:45 AM   #18  
Big

I use the die grinder with a burr on the end to clean the hole! But you have to be careful!

Larry

 
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10-28-03, 11:56 AM   #19  
sleepyfloyd
Originally posted by bigguy05641
I am wondering if the sensor that u are getting the reading of `0', is actually 'out-of-limits', which would indicate an open. Is it the same reading as when the leads to the meter are not connected to anything? If so, that sensor is definately the bad one.....
Toyotaman, I like your idea of heating the sensor up after pulling all the windings out. I usually go in with a die grinder to clean out the remaining bits of sensor housing......
I'm almost positive its an open.. there's no change in the reading at all when I connect the probes... Normally, if its a short with a very low resistance, you'll get an some indication on the display before it goes to zero.. I even switched to the continuity mode to see if I got a tone, which would indicate continuity... and it didnt beep.

Anybody have any idea what these things cost? All the local parts stores dont carry them.. Tthey go for $140 at Rockauto.com... does that sound like a reasonable price or should I check out my Chevy/Geo Dealer?

 
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10-28-03, 12:37 PM   #20  
Joe_F
Get the GM and Toyota #s and try www.parts.com or for the GM #, www.gmpartsdirect.com

I don't use either---I use a local dealer and get a trade discount. Not everyone can do that though . Shop around.

 
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10-28-03, 08:44 PM   #21  
sleepyfloyd
dang... for such a small part, its pretty expensive..

RockAuto.com gives me a price of $135 plus $5 shipping for a Raybestos Part.

ChevyGMparts.com gives me a price of $172 plus 10% shipping.. so thats $190 total.. but its a GM part. They quote the GM List price as $221.

Anybody have experience with aftermarket parts from Raybestos?

-sleepy floyd

 
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10-29-03, 04:04 AM   #22  
Joe_F
For something like a sensor, likely reboxed OEM.

 
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