Re: 1992 Toyota Truck Speedometer
Thought you guys might like a bit of resolution to this:
Thank you for all the help!
I resoldered the components and replaced the zener. That hot trace cooled off and the correct voltage showed up on pin 16 of the IC. But made no difference to the accuracy of the speedometer.
The final solution was to replace the IC (TB9213) with a "new" 30 year old component.
Again. Thanks for the help. Learned quite a lot.
ranchhandbumper
New Member
Last Activity: 12-13-2022, 10:56 AM
Joined: 11-11-2022
Location: Lilburn, GA
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Re: 1992 Toyota Truck Speedometer
I am not understanding or don't know what to look for withese ghost rings. My untrained eye and multimeter says things are OK on the bottom. Of the board. I can resolder, but could you point out exactly on the picture one of these ghost rings. I appreciate all of your help!Leave a comment:
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Re: 1992 Toyota Truck Speedometer
Ok. I am thinking about the hot crystal backwards then. The whole trace is very hot and the heat happens to feel focused most on those two points maybe.Leave a comment:
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Re: 1992 Toyota Truck Speedometer
heyyyyy, I think maybe its a bad zener?
So I get continuity in both directions on ZD2. (24k forward and 24k reverse)
Diode test on DMM shows 0.9V in reverse direction and 1.4V in forward direcion.
Also when voltage is applied to the circuit:
9V input = 6.3V output in both directions
11V input= 8.3V ouput in both directions
14V input= 11V ouput in both directions
Also, I have observed that the leads on the crystal (which I resoldered) are getting hot enought to be uncomfortable...Leave a comment:
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Re: 1992 Toyota Truck Speedometer
I have attached a picture. I cleaned the traces. I did not repair. Should I solder wire to each terminal on those traces? I haven't "repaired" because I have what I would call good continuity on those traces. I have very little experience with sensitive electronic components though....Leave a comment:
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Re: 1992 Toyota Truck Speedometer
Thank you all for the input:
Pin 16 is showing 8.75v at 12v input and 11v at 14v input (which i would assume is the more likely input voltage at cruising speed with a good alternator.) Does that mean ZD2 is bad? The resistor checks out ok.
Pin 9 outputs 5.4v to 5.5v no matter the input voltage.
I resoldered ZD2, the crystal, and C5 for good measure all to no effect. I will resolder the other suggested components, but thought the 11v on pin 16 was probably significant.Leave a comment:
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Re: 1992 Toyota Truck Speedometer
Thank you for the direction! It'll be few days before I get to it, but will post my findings.Leave a comment:
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1992 Toyota Truck Speedometer
I am working on a 1992 Toyota pickup that has an electric speedometer. It is an analog needle speedometer and is driven by electricity.There is no cable. The transmission has a reed switch that sends a 12 volt pulse to the speedo 4 times per tire rotation.
According to GPS, the speedo is showing speed progressively slower below 50mph and progressively faster above 50mph. This also affects the odometer.
I've included a photo of the findings. The "control" is information I found on the net that correlates expected MPH based on a given hertz.
I removed...Last edited by ranchhandbumper; 11-12-2022, 08:44 PM. -
Re: New Members - please post your introductions here
Hello from Lilburn, GA USA. For some reason a speedometer is the impetus for this new-found curiosity for electronics. Happy to meet everyone!Leave a comment:
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