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Replies:
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Last Post:
Oct 19, 2009 9:40 AM
Last Post By: quattro4ever
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Posts:
30
Registered:
06/18/05
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False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 25, 2008 11:17 PM
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My 96 A4Q ABS pump has been activating on its own, but there is no ABS/Brake light present.
What could cause this? Thanks.
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Posts:
400
Registered:
06/06/06
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 26, 2008 8:49 AM
in response to: quattro4ever
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Does the ABS function normally if activated by the brake pedal? Do the brake lights function OK when activated by the brake pedal? If the answer to both is yes then check the ABS control module - water in connector plug and or water/solder problem on circuit board.
Regards
Vdubbya
http://www.volkscity.com
http://www.volkscity.co.uk |
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Posts:
24
Registered:
06/02/08
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 26, 2008 4:58 PM
in response to: quattro4ever
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When you first turn the car on and start driving the abs system tests itself... you can hear or fell it activate.
That is normal. but if it does it at other times this is not the case
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Posts:
30
Registered:
06/18/05
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 26, 2008 6:04 PM
in response to: quattro4ever
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Yeah, the ABS/Brake lights lit up during selftest, and everything seemed normal until I start accelerating above ~15MPH, then the ABS start engaging.
I have swapped the ABS controller, same result. Unless both controllers are shot, this should mean the problem is on the connector, right?
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Posts:
400
Registered:
06/06/06
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 27, 2008 2:13 AM
in response to: quattro4ever
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Have you pulled some codes? It could simply be a faulty wheel sensor . . . .
Vdubbya
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Posts:
30
Registered:
06/18/05
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There is no DTC, but this my theory of what is happening:
Posted:
Aug 28, 2008 7:20 PM
in response to: quattro4ever
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I believe that one or more of the wheel speed sensors are faulty or dirty, and provide false speed reading to the ABS controller.
I think that the A4 has electronic traction control, so the system may be trying to limit the false slippage, and thus, activating the ABS.
Here is the bummer: 3 of the sensors look OK, the last one is stuck solid in the housing. I mean, I can't budge it at all.
I am tempted to start hammering the <blip>. Any idea before I destroy the <blip> out?
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Posts:
400
Registered:
06/06/06
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Re: There is no DTC, but this my theory of what is happening:
Posted:
Aug 29, 2008 5:13 AM
in response to: quattro4ever
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It is normal to find them corroded into place. Removal will probably destroy it so have a new one ready. They need to be checked electronically either with VAG-COM or an LED sensor tester. (The ABS wheel sensors generate their own signal) There is no other way of being sure . . . . .
Vdubbya
http://www.volkscity.com
http://www.volkscity.co.uk |
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Posts:
24
Registered:
06/02/08
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 29, 2008 10:40 AM
in response to: quattro4ever
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Eh? you can check them with a multimeter for resistance somewhere in the bently manual it will tell the proper resistence. but if your not throwing a code it might be within the parameters.
I had a sensor wire get stretched and I just cut the conector off and then the sensonr leaving enough to rewire with a serial cable from a computer soldier and heat shrink its been fine for 6 years now
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Posts:
400
Registered:
06/06/06
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Aug 30, 2008 9:01 PM
in response to: slimchriz
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An ohmeter check will only confirm sensor winding continuity and not necessarily its ability to generate an accurate and efficient signal. VAG-Com will monitor the sensors whilst driving. An LED type sensor testor will enable you to spin each wheel and test signal generation . . . .
Vdubbya
http://www.volkscity.com
http://www.volkscity.co.uk |
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Posts:
1
Registered:
05/21/09
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Re: There is no DTC, but this my theory of what is happening:
Posted:
May 21, 2009 9:34 PM
in response to: quattro4ever
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Were you able to solve this problem?
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Posts:
415
Registered:
02/23/09
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Re: There is no DTC, but this my theory of what is happening:
Posted:
May 23, 2009 3:13 PM
in response to: NL_B5S4
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Hi there, do you have same problem and what year and vehicle you have. I have not read fix post from previous guy, but if you have same problem let me know, be glad to help you out.
Bresha
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Posts:
1
Registered:
11/21/09
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Jun 30, 2009 11:54 AM
in response to: quattro4ever
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Most likely it it the reluctor (trigger) wheel, they will crack with age. You can catch it with scope, usually it's the rear. Requires replaceing the cv joint
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Posts:
54
Registered:
07/15/05
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Re: False ABS activation during low speed acceleration, no ABS/Brake lights
Posted:
Jul 21, 2009 3:31 PM
in response to: q_man
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^ Agree ^
Just did same with 01 A4. There were no DTC's for same issue of false triggering ABS while driving. Reluctor ring was cracked and broke into two pieces / fell out when touched during troubleshooting. New rear CV Joint fixed the problem.
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Posts:
30
Registered:
06/18/05
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Re: There is no DTC, but this my theory of what is happening:
Posted:
Oct 19, 2009 9:40 AM
in response to: NL_B5S4
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Yeah, it was the sensor. Actually, the sensor itself was fine, but it could not go into the correct position, so the wheel speed reading was marginal, and causes the ABS to engage.
I stupidly fixed it by hammering the sensor into place. I should have sanded the rust out, but I ran out of patience. This would be the second sensor on this wheel (had to destroy the old one since it did not want to come out).
Anyway, lesson learned is that when this happens, it would be either the sensor, or the tone ring.
Also, clean and lube your ABS sensors whenever you rotate your tires. This would probably have prevented the rust from locking the sensor in place.
Thank you all.
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