Gen 2 - ABS info, mod to ABS + Traction control?

Discussion in 'Gen 1 & 2 - Suspension, Brakes & Body' started by NoSlo, Jul 6, 2019.

  1. NoSlo

    NoSlo GoldMember

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    The G2 Taurus SHO uses a ABE Teves Mark IV ABS system. The computer and the modulator are all standard components, the pump it uses is optional (to recover pressure after ABS operations). Even when installed in different cars from different manufacturers, the ABS computers all use similar pinouts and connectors. The ABS computer likely gets some model-specific customization - number of wheel speed sensors (which can be less than four), number of sensor teeth & wheel diameter, options, etc.

    Here's a relevant and useful video for diagnosing this ABS system, as used on a Buick. The codes, pins, and diagnostic procedures are the same. Even look inside the ABS valve body.



    Now what's interesting, and gets one thinking - this ABS system also had a traction control option the car manufacturer could have selected. It could apply brakes to the slipping driven wheel when operating under 25MPH, transferring power to the non-slipping wheel. Mainly snow/ice traction, but also a poor-man's launch spin control.

    The 1994 Thunderbird SC had the traction control option installed, but for rear-wheel-drive. The Buicks in the video have traction control for front wheel drive, the way we'd want them to work. 94 Buicks can even signal the ECU to reduce power. On 1994 BMW3, you'll find the ABS + Traction control + Stability control using this system + dual pumps.

    Parts required for this:
    ABS Modulator body with two extra valves, plus pump return lines,
    ABS modulator computer with traction control enabled, ideally FWD to avoid re-wiring or re-routing,
    (Brake pedal position sensor), especially for SC, or pressure switch for TC
    Lots of wiring (and some re-hosing?), new bracket for ABS modulator.
    Maybe ABS master brake cylinder with return lines (?)

    This could be a long project for little performance return, but my interest in the possibility is already piqued...


    BTW, it looks like running the ABS pump manually in our cars might work as a built-in "power bleeder", which can be accomplished not just with the dealership ABS bleeder diagnostic module, but also by just plugging into harness with your own homemade "module" or plugging into the the ABS module/pump with your own junkyard pigtail. I'm going to a wrecking yard to get the last option to make an ABS flusher.

    (Later Teves Mark xx systems even allow you to use the traction control button and brake pedal to do the valve body flush procedure without any expensive diagnostic tool :mad:)

    BMW ABS + TC + Automatic stability control

    [​IMG]
     
    Last edited: Jul 8, 2019
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  2. sperold

    sperold Last to Know Supporting Member

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    Wow, that is a lot of information !

    Who knew the sophisticated systems of today are were available (in their infancy) back in 1990.
     
  3. NoSlo

    NoSlo GoldMember

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    Pretty advanced. Here's the inside of a controller (where a Jaguar owner fixes cracking solder joints):
    [​IMG]

    There are two stages of ABS. The first shuts off the normally-open brake lines to the particular wheel, which stops further pedal pressure. The second stage releases the wheel's brake pressure (back to the master cylinder) through normally closed valves. Then the ABS pump will raise system pressure and the pedal to compensate for the loss of pressure, the brake pedal pulsing you can feel.

    The second stage (outlet valves) is the one that needs special bleeding procedures to get air out of the module and return lines, if the pressure modulator valve body, pump, master cylinder, or nearby lines are replaced. This requires the T90P-50-ALA anti-lock harness module (and optional cable to convert the 55 pin ABS to a Ford EEC breakout box), or a similar aftermarket computerized diagnostic tool with 55-pin adapter:

    [​IMG]

    Running the pump ("start") will build master cylinder pressure, and at that point, one should also be able to open any caliper bleeder and get fluid flow. The "valves" button runs a program which opens and closes the valves (in mystery order) to flush air back to the reservoir. Then one must bleed normally RR, LF, LR, RF until fresh fluid is achieved.

    I expect I will be able to achieve similar function, just applying power to the motor and the valves manually, using a powered box with switches, hooked directly to the valve body solenoids and pump wires. With a 55-pin connector that plugs into the harness, instead, we can do a more advanced bleed, for example, stopping automatically if the fluid level sensor indicates low, as well as directly diagnosing all the sensors.

    Hydraulic line routing:

    [​IMG]

    You can see with the ability to close the inlet valves, not only is brake pedal input stopped, but also the caliper will hold the current pressure. If instead a wheel slips while not braking, traction-control or stability-control mode would shut all the inlet valves except the affected wheel, and pump pressure to the slipping one.

    Reference, ABS module pinout (along with additional pins used by TC-enabled module):

    [​IMG]

    (information 15 years late?)
     
    Last edited: Jul 9, 2019
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