Car lurches and jerks at low speeds (Help needed!)

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Car lurches and jerks at low speeds (Help needed!)

Postby Vazzter » Tue Jul 09, 2019 2:53 am

Hey everyone, I have recently purchased a 2008 Subaru Liberty 2.5i and have been looking around for answers to this issue for a while now.

My issue is the brakes are jerky, unstable and jittery when applied at low speeds. in 1st, 2nd and 3rd gear, braking (with or without the clutch in) the brakes tend to lurch, jitter etc. There is a clunky noise every time the car jerks, feedback from the brake pedal and when the headlights are on at night they dim briefly, there is no wheel feedback when this happens. I have once seen the Traction control light flash up on the dash (not the light that lights up when you press the traction control button). I had the car serviced last week, they scanned the car for error codes and produced the following:

C0071 (Steering angle sensor)
C0026 (RHR wheel speed sensor fault) -(in history)
C0043 (Power supply voltage failure)

My mechanic explained that these codes may have occurred well beforehand and may not apply to my issues. My mechanic suspects that the ABS system is either faulty or has failed, and at low speeds fails to detect the wheel speed, thus engaging the ABS system which causes the jittering and lurching of the car. He has cleaned the ABS sensor but the issue still persists. I'm considering pulling out the ABS fuse and testing the car on a safe back-road to confirm that the ABS system is faulty and disengaging the brakes, which is causing my brake pedal to have feedback and the car to lurch.

If anyone has any information on this issue, has happened to them, or knows of this issue and can direct me to a thread which pinpoints this issue, I would greatly appreciate it.
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Re: Car lurches and jerks at low speeds (Help needed!)

Postby RX25SE » Tue Jul 09, 2019 12:54 pm

Perhaps go for a drive with the scan tool connected and read 'live data' on the wheel speed sensors. Check they all read the same value.
Testing with fuse removed is also a good idea.


I would be replacing the ABS unit only after all other diagnosis has been carried out, as mostly it's sensors or wiring issues that cause faults.
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Re: Car lurches and jerks at low speeds (Help needed!)

Postby bigBADbenny » Wed Jul 10, 2019 10:33 am

Also review the DTC’s diagnostic trees in your FSM, link in my signature.
The fixes usually start with the basics, eg loom continuity; progressing to system inspection and testing.
Once you’ve exhausted all the checks, and if the abs module or controller is the culprit, the cheapest way forward is usually a numbers matching unit from a self serve wreckers.
You can cross check the part compatibly across all models using info in the aforementioned link.
You can also use the “google this forum” link in my signature to search this site by the issues description or DTC code to see if anyone has had the same issue.
Eg: https://www.google.com.au/search?biw=32 ... cRABTJ_UZs

...
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