1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Broken Speedometer Repair

Discussion in '80-Series Tech' started by gummycarbs, May 17, 2017.

  1. gummycarbs

    gummycarbs

    Messages:
    262
    Likes Received:
    168
    Joined:
    Apr 14, 2016
    Location:
    Oregon
    When I bought my '94, the speedometer didn't work. I did some Googling and turned up the VSS as a likely culprit. There was a good deal on NOS Toyota units on eBay, so I bought one. Didn't fix it.

    I read somewhere (here or maybe Expedition Portal?) about the speedometer circuit board looking 'burnt'. Sure enough, mine did, right at the top:

    [​IMG]

    I took a brass brush to it (the 'toothbrush' type) and the "burnt" stuff came right off, revealing two damaged circuits:

    [​IMG]

    The left half of the top circuit was still intact, but looked really sketchy, so I did a two-step repair on that part. The speedometer works great now, though the tripmeter is still non-functional, except for the tenths digit.

    [​IMG]

    I don't know what caused the circuit to fail like that. I can't imagine that it's somehow collecting moisture there. The lower circuit is really thin, so I can see how it might eventually burn out, but it still seems weird. I noticed that there are a few capacitors that look like the Nichicon ESR capacitors that are known to leak and corrode circuits. Lexus guys have found that leaking capacitors are damaging their ECUs in a similar way, but I haven't read much about that on Mud. Here's a link to the discussion on Club Lexus:

    All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor) - Club Lexus Forums

    Hope that helps someone.
     
    Last edited: May 17, 2017
    shocktower and Malleus like this.
  2. shocktower

    shocktower

    Messages:
    898
    Likes Received:
    612
    Joined:
    May 20, 2009
    Location:
    Canby Oregon
    Yeah I want to fix my trip-meter, dam thing died :crybaby:
     
  3. 22re92

    22re92

    Messages:
    4
    Likes Received:
    0
    Joined:
    Oct 12, 2017
    Location:
    PNW
    My circuitboard looks almost identical to yours, did this work?
     
  4. gummycarbs

    gummycarbs

    Messages:
    262
    Likes Received:
    168
    Joined:
    Apr 14, 2016
    Location:
    Oregon
    Yep, it's been working great for months.

    I recently discovered a product that would probably work great for repairing these kinds of problems without soldering: CAIG CircuitWriter. It's a conductive ink pen. $20 at Fry's.
     
  5. 22re92

    22re92

    Messages:
    4
    Likes Received:
    0
    Joined:
    Oct 12, 2017
    Location:
    PNW
    Hah! I actually just tried that without success. Going to try doing the wire method you used.
     
  6. gummycarbs

    gummycarbs

    Messages:
    262
    Likes Received:
    168
    Joined:
    Apr 14, 2016
    Location:
    Oregon
    Ah, bummer to hear that.
     
  7. 22re92

    22re92

    Messages:
    4
    Likes Received:
    0
    Joined:
    Oct 12, 2017
    Location:
    PNW
    Is there a particular type of wire you used to solder the joints together? Here's what mine looks like:

    [​IMG]
     
  8. 22re92

    22re92

    Messages:
    4
    Likes Received:
    0
    Joined:
    Oct 12, 2017
    Location:
    PNW
    By the way, thanks for your fast response!

    Update, attempted the wire solder without success. It's possible I need to make more connections or that my soldering skills are bad. Will attempt more tomorrow:

    [​IMG]
     
  9. gummycarbs

    gummycarbs

    Messages:
    262
    Likes Received:
    168
    Joined:
    Apr 14, 2016
    Location:
    Oregon
    When I did mine, I put a multimeter on contacts along the various circuits checking for continuity.

    And you might want to get a softer brass-bristle brush. It looks like yours was a bit harsh. :)
     

Tags: