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98 Disco I - how to reset ABS light?

colddudecolddude Posts: 4
edited May 10 in Land Rover
My Disco has been reliable until recently (80K miles on original Michelin 4x4 XPC). First it was water in ECU ($430), then I couldn't shift out of PARK (the brake-stop switch had to be replaced). Immediately after replacing the switch, ABS light came on. I think this is due to the brake-stop switch, which is part of the ABS circuit. Now I just need to reset the ABS light, right?

Anyway spent 2 evenings Googling about this, and found such a massive ABS-light problem reported by Land Rover Disco/RR owners, more infamous than Debbie from Dallas. What a shame! Worst is there is no good advise on how to deal with it - I gathered this is a complex problem, and you can go broke (or go crazy) if you try replacing bits by bits.

The car drives fine, but no opportunity to test to see if ABS is actually working. All I want to do is to reset the light. Some advised to jumper 2 pins on the ABS diagnostic connector to clear the code, but I was not able to find the connector in my 98 Disco I (Canadian model). Called dealer and was told one would need scantool (OBD) to reset the fault (or pay $100 to check it out) - bought one today ($130) but the OBD reader did not pulled up any fault codes (got GREEN light and no fault code).

Some suggest ignoring the light. What I worry about is not having ABS working, and I have been saved by ABS several times driving on icy mountain roads, particularly relying ABS to go downhill on icy roads.

It feels like I've reached the end of the Internet, as I can't find an easy instruction to clear the ABS light. I am looking for that one Land Rover technican who can answer this decade-old question, for all of the Disco owners.

Please, please, please...

Comments

  • jhh001jhh001 Posts: 2
    Did you ever get an answer on this problem. I have it too.
  • Excellent article on the ABS problem by John Robison at RoversNorth .....

    Welcome to the techie column for the Fall edition of
    the Rover News. In this column, we’re going to look
    at some of the common problems with the antilock
    brakes on Discovery II models. The Discovery II electronic
    braking system, called SLABS (self leveling anti
    lock braking), is made by Wabco of Germany. Wabco
    is a subsidiary of American Standard, a company better
    known to the public for toilets than brakes. In the
    automotive field, Wabco specializes in braking and
    suspension systems for trucks. According to the company,
    two out of three commercial vehicles with
    advanced braking systems are equipped with Wabco
    products.
    The Land Rover system includes four-wheel
    antilock braking, hill descent control, and four-wheel
    traction control. The SLABS control unit also controls
    the self-leveling suspension, if the vehicle has that feature.
    The Discovery air suspension is also a Wabco
    product. As an aside, Wabco air suspension is also
    found in the new Audi A6 and the Mercedes CLS.
    One of the most common ABS questions I
    hear is, Why do I see the ABS, Traction
    Control, and Hill Descent lights coming on?
    All three of those systems share a common set of
    core components. The wheel speed sensors, the hubs,
    the modulator, the controller, and other parts serve all
    three systems. So a fault in any one of them will cause
    a problem in the other two. It is actually rare to have
    a fault that would only disable one of the three systems.
    99% of the time, if one is affected, they all are.
    To see what’s wrong, you will need to connect a
    Land Rover test system and read the faults. These systems
    are not OBD II compatible, so a generic scanner
    won’t talk to them. At Robison Service, we use the T4
    or Autologic tools for this work.
    The most common faults are wheel speed
    sensor faults. The wheel speed sensors in a Land
    Rover are coils that sense the motion of a toothed
    wheel that’s a part of the wheel hub. The rotation of
    the wheel induces a sine wave signal in the sensor
    whose frequency is proportional to the speed, and
    whose amplitude increases with speed from 0.5 volts
    to more than 5 volts.
    If your Rover has a speed sensor fault, there are
    two paths to repair. The first is to replace the entire
    hub on the affected corner. This is the approach
    favored by dealers because the toothed wheel – called
    a reluctor ring – and the actual sensor are both part
    of the hub. The reluctor can get damaged by rust or
    corrosion, and it can also get damaged by a bad wheel
    bearing. The only way to service it is to change the
    hub.
    As of this writing, hubs (front-RND646 / rear-RND694)
    cost around $400 and take about three hours to
    change.
    The sensor can be removed from the hub fairly
    easily. If you remove your sensor and look inside you
    should be able to see if the reluctor ring is damaged.
    The reluctor ring can get damaged if the wheel bearing
    gets loose. It can also get damaged by corrosion.
    That’s especially true for Rovers that run on beaches.
    If you see reluctor ring damage, or corrosion, or if the
    hub has any free play at all – you need a complete
    assembly. If there is no damage, you may be able to
    fix the vehicle by changing the sensor (front-RN292 /
    rear-RNH293) alone, a $100 part that’s less than an hour
    to swap.
    The path you choose should be determined by
    examination of the reluctor via the sensor hole. If the
    hub looks good, there’s an “8 or 10” odds that a sensor
    alone will fix your problem.
    Every now and then you will see a Rover that has
    wiring problems, usually at the connector between ABS
    sensor and body. Always pull it apart and look for
    corrosion.
    The next common fault in these systems
    is called shuttle valve failure. The shuttle valve
    is a part of the brake modulator – that big thing in the
    location where a master cylinder would be. The modulator
    incorporates the functions of an ABS servo and
    a brake master cylinder into one unit.
    If you have shuttle valve problems, you will see
    the three warning lights on the dash and there will be
    one or more stored faults for shuttle valve failure.
    Land Rover has a test procedure to determine if these
    faults result from a failure in the modulator or if they
    are caused by wiring troubles in the ABS harness or
    grounds. Unless you have corroded grounds and
    cables, your trouble is probably in the modulator.
    Until now, this problem was addressed by
    replacement of the brake modulator (RNH082). That’s a
    $1,500 part. As you can imagine, shuttle valve failure
    produced a lot of unhappy owners and Land Rover
    finally listened up and developed a fix.
    As of March 2006, Land Rover sells a shuttle
    valve repair kit for under $100. You will have to
    remove the modulator and flip it over to install the
    valves on a workbench. Removal of the modulator,
    replacement of the valve, and refit to the vehicle takes
    three hours or so.
    This shuttle valve repair is a huge improvement
    over the former method of addressing this problem.
    The part number for the repair kit is (SW0500030).
    If you buy it from a dealer you may also want to ask
    for the March 2006 bulletin that gives test and installation
    instructions.
    Another common problem is a mushy
    brake pedal. In my experience, the only explanation
    for a mushy pedal is improper bleeding procedure.
    Bleeding a Discovery II takes two people and the Land
    Rover test system, and it takes the two of them a bit
    over half an hour. You need the tester to operate the
    pump and valves to make sure all the air is purged
    from the modulator.
    If you are paying for this service, expect a labor
    bill in the range of one and a half hours and $20-30 of
    brake fluid. If you are not at a dealer, make sure they
    use the correct Castrol LMA fluid. Don’t even start this
    process unless the shop has a tester to run the pump
    and valves. You could bleed brakes in the field without
    one in an emergency, but there is no way to get a
    really good pedal without cycling pump and valves.
    There is no shortcut for this job. You need two
    people and the Land Rover tester.
    We see quite a few stop lamp circuit
    problems. The usual way this problem manifests
    itself is a truck that won’t shift out of park. Discovery
    II models have an interlock that prevents shifting out
    of park unless the brake is pressed. So, if the brake
    light circuit fails, the car won’t go into gear.
    If that happens to you, the first step is to check
    the stop lamp fuse. We’ve seen several trucks where
    the stop lamps were fitted wrong, or the contacts corroded,
    and the fuse blew. Also check the trailer connector,
    if your Rover has one. A short there can pop
    fuses.
    If the fuses are good, you should check the stop
    lamp switch. It’s located above the brake pedal. If
    you are stuck somewhere, it is possible to get out of
    park by jumping the switch temporarily with a paper
    clip.
    Finally, you should check your Rover to
    see
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