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MCP819
Anonymous Poster
MCP819@hotmail.com
Mar 4, 2007, 2:46 PM
Post #1 of 6
(4013 views)
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ABS Brakes/1996 Camaro
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I own a 1996 Camaro and the ABS in op light is continuously on. I have replaced both front wheel sensors; no luck. I noticed, if I apply the brake and start the car, the ABS in op light goes out and won't return until I release the brake pedal. Can anyone advise what is causing the ABS to mal-function?
Thanks,
John
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DanD
Veteran
/ Moderator
Mar 5, 2007, 6:29 AM
Post #2 of 6
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Re: ABS Brakes/1996 Camaro
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Have the code(s) read and tell us what they are. Codes usually won’t tell us exactly what’s wrong but they’ll give us an avenue to look in.
Dan.
Canadian "EH"
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mcp819
Anonymous Poster
mcp819@hotmail.com
Mar 5, 2007, 1:00 PM
Post #3 of 6
(4005 views)
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Re: ABS Brakes/1996 Camaro
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Dan, The local dealership checked the system and identified three codes. The first two dealt with he left front wheel sensor (the wheel hub has been replaced) the second code dealt with the "ABS motor". Mechanic believed that the wheel sensor malfunction was triggering the "ABS motor code".
Is the ABS motor repairable?
John
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DanD
Veteran
/ Moderator
Mar 5, 2007, 1:19 PM
Post #4 of 6
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Re: ABS Brakes/1996 Camaro
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I haven’t checked but I believe it’s serviced as a complete assembly.
Dan.
Canadian "EH"
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mcp819
New User
Mar 5, 2007, 5:20 PM
Post #5 of 6
(3998 views)
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Re: ABS Brakes/1996 Camaro
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Dan, The technician using the Tech 2 Test came up with three codes: C1221, C1225 and C1247. I am not sure what the c1247 code indicates. It reads "Left Front ABS motor free spin" I don't know what that means; can you help me? What needs to be done?
Thanks,
John
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DanD
Veteran
/ Moderator
Mar 6, 2007, 6:34 AM
Post #6 of 6
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Re: ABS Brakes/1996 Camaro
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To diagnose the C1247 code; a scan tool with the same capabilities as a tech 1 or tech 2 scanner will be required to perform actuator tests.
The free spin could mean that the gears between the left front motor and the left front modulator are stripped and are “free spinning”. The gears are replaceable but again a scan tool is required to release the motor tension on the gears. No doubt there are ways of doing this without a scanner but I’ve never attempted and have always followed the repair procedures set out in the manual.
The only thing though before you start going after the gears is that I’ve always read and followed, is to repair the codes in the order they were presented.
Also C1221 (left front wheel speed sensor input signal equals zero) and C1225 (left front excessive wheel speed sensor variation) both are dealing with the left front along with the C1247.
I would be going after the cause of these two first, making sure that the ABS module was getting all the proper inputs.
If the module is getting conflicting information from the left front wheel speed circuit, it maybe triggering a false free spin code?
Notice how I said wheel speed circuit and not just the sensor, the problem maybe in the wiring between the sensor and module?
The best way that I’ve found to check the complete circuit is with the use of a lab scope, set up to read the waveform coming from the sensor. I back probe the Module’s connector to get my scope connected; that leaves the system connected and intact.
Then I spin the wheel in question at a constant rate; while pulling, twisting at the wiring harness and its connectors. I’ve even been known to hit sensors to “simulate road shock”. (GM’s term, they wouldn’t say hit the damn thing) Watching for any form of glitch in the wave pattern on the scope.
So my friend I think you’re into buying the equipment and learning how to use it or taking the car in and let someone go at it?
One last thing, whose wheel speed sensors, did you use? I’ve had problems with after market sensors. They fit perfectly, look the same but are (at times) just a little different electrically, enough to cause all kinds of issues. I’ve also been caught thinking it can’t be the sensor it’s brand new? NOT!
Dan.
Canadian "EH"
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