speedo pin-outs

[Devinder]

I need to bench test a speedometer. Has anyone tried to test thiers by supplying 12V and somehow simulating the chopper signal?

Devinder

[a]

No, but you have piqued my curiosity. Lemme go dig up my ETM, fig 6210, IIRC.

[a]

uhhmn, near as I can figure C12 is the 5 pin board connector on the speedo.
C12 pin 1: Br/bu:=>. br /rd from the sender
2: comes from ground side of charging lamp?
3: ground and brown from sender ( makes sense)
4: 12v from key
5: NC
The sender is magnetically pulsed reed sw. pulsed by the ring gear, prolly could substitute a metal disc on a motor? bicycle wheel? Hope this helps. please post results TIA . PS, those injectors you sold me are still working fine

[Devinder]

I think this might work. I can simulate the signal easily using a function generator to drive a solid-state relay to switch ground.

It is kind of wierd that there is a wire color given in the connector. The connector is just a header from one PCB to another. I'll have to look at it and see if the pins make sense.

Devinder

[a]

the wire color was my doing . The ETM diagram had them . The pinout was constructed by me working from the drawing 6210-0. I included the wires in case you needed them . When I was trouble shooting the dead speedo on the Grape, the change in the signal wire from br/bu to br/ rd threw me a curve. . Please post your results, including what you used to generate the signal. I have a few dead speedos I would like to play with. TIA

[Devinder]

The pins on the speedo are labeled "A", "+", "-", and "31B". Does the speedo take 12V or is there a power circuit on the man instrument cluster board that reduces it to 5V? I don't want to blow the chip on the speedo board.

[a]

key power, 12volts, enters the IP at C1, pin 7, this is direct to 4 of C12. In the schematic, there is a + just inside the block out line that depicts the speedometer. The 4th connector from the top is the + so I'm GUESSING 12volts is OK. The speedo drive is a motor of some sort And I do know that the fuel and temp gauges use 12volts . ................... I'll do some searching and see if I can find an online ETM and you can decide.
http://www.warriorscentral.com/533/ETM%20e28_86.pdf page 58
Thanks Donnie J

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[Devinder]

It works great! 12V to the + and - terminals and then switch ground to pin 31B. 100 Hz is about 45-50 mph

Devinder



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[a]

great , are there any cheap sources for the simulator you used ?

[Devinder]

I don't know about cheap, but all you need is a relay to switch the ground and a function generator to drive the relay with a square wave. If you use a solid-state relay, then you can get by with a small function generator. I used a regular electro-magnetic relay and drove it with an old function generator capable of putting out good current. You could also drive it with an audio amplifier.

Another idea is to use an audio editing program on your computer to generate something resembling a square wave and then use the headphone output to drive a transistor.

Devinder

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[RonW]

Another idea is to use an audio editing program on you computer to generate something resembling a square wave and then use the headphone output to drive a transistor.

The basis for the speedometer circuit is the UAF 2115 Speedometer and Mileage Indicator. The datasheet is available on the web. It looks to me like an NPN transistor would work just fine. Ground the emitter, drive the base with your function generator/PC audio output (through a resistor) and connect the collector to the pulse input on the speedometer.

[Edited 12/31/2007 to enable BBCode]

[Devinder]

What a bitch. I finally figured out what was wrong with my odometer. One of the coil wires for the stepper motor drive was broken. I had to repair it since it's a specific M5 part. The wire is buried inside the assembly so I had to de-solder the meter from the board to fix it.

Devinder

[rudisnartiss94]

What a bitch. I finally figured out what was wrong with my odometer. One of the coil wires for the stepper motor drive was broken. I had to repair it since it's a specific M5 part. The wire is buried inside the assembly so I had to de-solder the meter from the board to fix it.

Devinder

Hi, greetings from Latvia!
Hope someone is still live up here.
Same problems with speedo, changed gears but still not working odometer, figure that it can be the same issue ,
can you share a photo of these loose connections on the coil ?

[Mike W.]

You might want to try emailing him, but even that doesn't work well. Devinder is still around, but doesn't come here very often anymore and this thread is almost 20 years old.