Strange ABS issue |
Post Reply |
Author | ||
ADK
Groupie Joined: 03 Apr 18 Status: Offline Points: 48 |
Post Options
Thanks(0)
Posted: 13 Dec 18 at 16:37 |
|
Hi, The problem: ABS live data is showing that the van is still moving even while it is stopped. When tested on a rolling road, the brakes work correctly. The ABS readouts show no faults. However, even when the van is completely stopped, the live data shows that the van is moving at 1.8km/h. The only symptom I have is a 'judder' in the couple of seconds before the van comes to a complete standstill when I apply the brakes. The background: My LT35 was in for a service recently, and I was told brake discs needed replacing, which the garage did. I got the van back and straight away, I noticed that the van had acquired a fault: 1.when the brakes were applied 2.as the van was coming to a standstill 3. there was a 'judder' on the brake pedal. It only happens in that second or two before the van stops completely and it happens every time. I continued to drive it and at one point the ABS light came on briefly. I took it back to the garage, they agreed that the symptoms described were present and after investigating, told me that an ABS sensor had probably been damaged or moved during the brake disc replacement as it was showing a fault on the ABS readout. They replaced the sensor and have phoned my to describe the situation as laid out in the first paragraph above. They also tell me that the 'judder' has not been cured but suspect that it is related to the fault which tells the ABS that the van is still moving. I am yet to collect the van, which I will do tomorrow. Any thoughts? Because I don't know what to do from here. And I have no idea whether it is safe to drive! Thanks in advance for any input. |
||
Lancashire
LT35 80kw TDi - 2005 MWB/Hi-top |
||
mojo
Groupie Joined: 04 Dec 11 Location: Liverpool Status: Offline Points: 179 |
Post Options
Thanks(1)
|
|
If replacing the sensor hasn't fixed it, then it's more likely they've damaged the wiring to the sensor.
Did they give you the abs fault code? |
||
tellytubby
Groupie Joined: 29 Mar 16 Location: Glasgow Status: Offline Points: 154 |
Post Options
Thanks(1)
|
|
The symptoms are similar to a common Saab problem which is corroded reluctor rings ( the cog thing on the driveshaft that the abs sensor points at ).
As the teeth on the ring wear out the abs sensor gets less signal especially at low speed so you get an abs activation just as you pull up. Could be something to look at - also check the abs sensor is in correct location if too far away youd get same sort of thing. |
||
ADK
Groupie Joined: 03 Apr 18 Status: Offline Points: 48 |
Post Options
Thanks(0)
|
|
Thanks very much for the replies, they are appreciated.
Excellent - thanks for the information. I did hear from the garage late on Friday and they had come up with the reluctor ring as a possible problem, so they've ordered one and will be fitting it tomorrow. I have done a bit of a crash course on ABS systems so I did a bit of reading and as you mention, it is not an uncommon problem. The fact that it occured at the time they worked in that area is my only reservation. One detail i got wrong was that they had changed the hub seal in that area, not the brakes. As for the distance to the sensor, is that the air gap? I did some reading and mentioned it when I spoke to the garage and they told me they had checked the air gap and it was fine. The other thing I've come up with as a possible issue is uneven tyre pressure, so I will mention that if the reluctor ring doesn't cure it. Thanks very much for all input, I'll provide an update when I have mroe information.
|
||
Lancashire
LT35 80kw TDi - 2005 MWB/Hi-top |
||
ADK
Groupie Joined: 03 Apr 18 Status: Offline Points: 48 |
Post Options
Thanks(1)
|
|
...and the problem has been solved. It was indeed the reluctor ring. It was the tiniest dent in the surface of the ring. It wasn't visible, it was something you had to feel by running a thumb over the surface. Difficult to believe but that slight distortion in shape was enough to trigger the ABS. New Sensor The old ring Thank you for all replies. |
||
Lancashire
LT35 80kw TDi - 2005 MWB/Hi-top |
||
mojo
Groupie Joined: 04 Dec 11 Location: Liverpool Status: Offline Points: 179 |
Post Options
Thanks(0)
|
|
Thanks for the update, glad your sorted.
|
||
2006 LT35 TDI 109 AVR
|
||
Post Reply | |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |