Speedometer not working (all other gauges work)

[boom10ful]

I would try resoldering everything there before condemning the hall effect sensor. This place says that an alternative is available.... just food for thought


https://www.onlinecomponents.com/en/hon ... 42282.html

[Tom]

I would try resoldering everything there before condemning the hall effect sensor. This place says that an alternative is available.... just food for thought


https://www.onlinecomponents.com/en/hon ... 42282.html

Good call. Worth a try on reflowing the solder joints, and it does seem very likely that some other Hall effect sensor could be substituted.

[Goodwood]

Tom,
If it’s just the odometer, that’s a common failure. My 83 944 had the same issue. They have plastic parts in the cluster that disintegrate. I had mine fixed at a Speedo repair shop in Phoenix, AZ and it was under $200 back in 2016 or 2017. Hope this helps!

[Synapse120]

I would try resoldering everything there before condemning the hall effect sensor. This place says that an alternative is available.... just food for thought


https://www.onlinecomponents.com/en/hon ... 42282.html

Re-soldering was a no go, found out those things are super fragile, and the Hall effect sensor quickly became detached from the pins. Upon re-soldering to the pins still doesn’t work. Here is the underside of the board. Feels like something that can be re-produced.

image.jpg (3.5 MiB) Viewed 919 times

[Tom]

You could probably do a one-off with just a perf board since there is so little to it. I've used a number of places to make small-batch PCB's though if you wanted to go that route and needed help. I'm no pro by any means, but have Eagle for circuit design and could do something like this fairly easily. Just need to confirm the values of the parts, and how they connect (i.e., the circuit).

[Tom]

Tom,
If it’s just the odometer, that’s a common failure. My 83 944 had the same issue. They have plastic parts in the cluster that disintegrate. I had mine fixed at a Speedo repair shop in Phoenix, AZ and it was under $200 back in 2016 or 2017. Hope this helps!

Carpokes has you covered on that next time, though hopefully there is no next time. In this particular case, it sounds like the speedometer/odometer works, but just isn't getting a signal from the sensor in the transaxles.

https://www.carpokes.com/viewtopic.php?t=900

https://www.carpokes.com/viewtopic.php?t=901

[Synapse120]

You could probably do a one-off with just a perf board since there is so little to it. I've used a number of places to make small-batch PCB's though if you wanted to go that route and needed help. I'm no pro by any means, but have Eagle for circuit design and could do something like this fairly easily. Just need to confirm the values of the parts, and how they connect (i.e., the circuit).

I’m using expressPCB to build out the board necessary, looks like a diode, resistor, and perhaps a small farad cap. since i have two boards from two bad sensors, I’m validating the copper traces in the factory board via continuity testing with a volt ohm meter. I’m going to see what i can make work in terms of Hall effect sensors in the factory spot with a new board.

What I’ve learned is the gear in the transaxle turns the magnet in the sensor which i think as it rotates changes polarity that triggers the hall sensor into sending ground pulse on the middle pin of the sensor.

[Synapse120]

Got my PCB designed from a circuit perspective, gotta tweak the size and try to get it the correct shape to fit the factory housing.

image.jpg (3.39 MiB) Viewed 850 times

8B61500A-19FD-46DD-AA3A-080C444FBA53.jpeg (1.53 MiB) Viewed 850 times