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97 LX-450 4wd low operation

Discussion in '80-Series Tech' started by VRcrewchief, Feb 12, 2018.

  1. VRcrewchief

    VRcrewchief

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    I had a question on the operation of 4wheel low in my Lexus LX-450. The shifter will go into low but I get no Diff Lock indication on the instrument panel. I believe that this should automatically happen in low. I do see the A/TP momentarily light when in park or N as I shift from H to L. The gearing seems to “lug down” as if something has shifted in the center differential but I get no indication that all wheels are pullin together as when they are locked. I know that this worked years ago but I have never needed or exercised this option recently. Would this bea center differential lock switch, motor or solenoid? I’m not sure if there’s a fuse in the system for the solenoid. I heard that there is a mod that can be installed with a CDL switch in the dash along with a pin 7 mod. I currently do not have these installed yet. I am kind of new to this so any advice would be greatly appreciated. Thanks.
     
  2. whaler

    whaler

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    The mod is just adding an OEM diff lock switch to the dash, theres an existing harness from the factory back there but no diff lock switch. This lets you lock in High. The pin 7 allows you to select diff lock or unlocked in Low.

    it could just be the illumination in your instrument panel is out. It sounds like you are getting the center diff locked in low. Take it on loose gravel or something not like asphalt and it should be obviously vs. unlocked.
     
  3. -Spike-

    -Spike-

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    The CDL locker sensor switch often fails, especially when not exercised regularly, which means no signal to the dash indicator light. If you don't have axle lockers this won't affect anything else, if you do have axle lockers they won't function without that indicator lit.

    If you turn the key 'on' but don't start the engine, shift to low, you should hear the relay in the left kick panel and the motor on the transfer case. That doesn't guarantee that it locks, but it's a start. If it is locking, slow tight turns in dirt or gravel should result in some tire slippage.
     
  4. VRcrewchief

    VRcrewchief

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    Spike, thanks for the reply. If I understand you correctly, technically I can bring 4wd low but not locked if the switch or solenoid are not working properly. I did not hear a relay in the left kick panel or the motor on the transfer case. I did find a fuse in the fuse panel for the differential but it was good. The CDL Lock sensor switch looks a little difficult to get to and I’m hoping that is all it is. Thanks again.
     
  5. scottryana

    scottryana

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    Your axles will not automatically lock. Unless you have a triple locked 80. To lock the axles there will be a dial switch on the left hand side.

    The only thing that automatically locks when you go into low is the center differential lock.

    I am not sure if you are sure of what you are asking. Do you get any indication on the dash? Do you know if your truck has lockers for the axles or are you only looking for the center differential lock?


     
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  6. -Spike-

    -Spike-

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    If it's only the sensor switch (that tells the locker ECU that the locker is engaged) that is not working, it will still lock the CDL, but you wan't get an indicator light. If you had axle lockers, they would not work without the indicator light working.

    If you're not hearing the relay or motor for the CDL when you put it in low, you have other issues.
     
  7. VRcrewchief

    VRcrewchief

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    Thanks again all. I'm still not sure I have all the terminology down. Although I have had the vehicle for 15 years, my primary transportation has been a 99 4 Runner and its only recently that I have become interested in the full capabilities of the LX450. It appears that there were options available but mine did not have the locker switch installed at the drivers side left knee. All the dash indicators are present for the CDL on the left side of the dash as well as front and rear Diff lights on the right side of the dash. The front and rear lockers would not apply in my case since there is no Diff lock switch installed. According to the owners manual, the CDL light should illuminate when in low along with the ABS light. Neither the CDL Diff Lock nor the
    ABS lights come on in Low although the gearing feel is noticeably different. I am almost certain that the Diff Lock light came on years ago when I went to low as well as experiencing the “wheel slipping”in a turn on soft surfaces. Hopefully this is not a major repair if in fact it is bad. Again, I am not hearing any relay or motor noise when going to low which I believe means I am not truly “locked”. It’s all kind of new to me and I appreciate your inputs. Thanks.