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FIX for WEIRD ABS code 49 problem caused by leakage voltage in stopswitch circuit

Discussion in '1st Gen. Tacomas (1995-2004)' started by offset442, Dec 8, 2008.

  1. Dec 8, 2008 at 1:07 PM

    offset442 [OP] Member

    Dec 8, 2008
    ABS Code DTC 49 when running / headlights are on:

    I have a 2000 Tacoma, that has been driving me nuts with a weird problem with the abs.

    what happens is that during the daytime the abs works fine,

    however when i turn on my lights, specifically the exterior lights not the headlights

    it causes the voltage on the low side of the stop switch to rise from .64 volts to 1.6 volts triggering the code 49 on the abs unit. ( 1.5 volts triggers code)

    also i noticed that when i move the shifter from the park position, it raises the voltage in the stop circuit an additional .2 volts for a total of 1.8 volts

    I measured the current for this 1.6v leakage and found it to be 1.1 ma

    so my band aid solution for this after spending half a day dismanteling and probing my trucks darkest recesses, was to intersect the stop circuit near the shifter and add a 500 Ohm 1/2 watt resistor between the STP circuit and ground, now the voltage sits at around .45 volts when my lights are on. note when you step on the break peddle this circuit gets hot with 12v @15 amps, don't just short it!! you will blow the stop fuse under the hood, and not be able to shift your truck out of park unless your like me and throw the interlock silinoide & lock-pin away while you have it appart

    I know that something is still wrong and I woundering what it could be?

    I thinking perhaps a defective ecu or something as the stop circuit goes to serveral places.......


    ECU, cruse, ABS, Shift lock S3 and s4, Diff lock, 3 light bulbs, 2 silinoids and a really nasty undocumented part called the intragration relay
    ( anyone know if the "IR" is solid state? )

    well from here on i'm stumped


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