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| Speedo quit working (Page 1/1) |
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Kappy
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SEP 16, 07:09 PM
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Speedo quit working. Last couple of weeks it was bouncing around, but would settle down and be fine. Today it just stopped working. Odo's still working fine, which makes me think it is the Speedo itself & not the sender on the trans. Got any thoughts?
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fierofool
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SEP 16, 07:47 PM
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I think your diagnosis is correct. The VSS is working else the trip odometer wouldn't work. The stepper motor for the speedo can be replaced without replacing everything. I'm told that the two stepper motors on the back are interchangeable, but there may be a difference in the shape of the little plastic harness end that plugs to the circuit board. It might be possible to swap positions with the wires, similar to what you can do with the AC and fuel pump relays, as a method of troubeshooting.
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Gall757
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SEP 16, 09:56 PM
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Make sure the tach filter circuit is not open. I found a bad connection there by wiggling the wires.
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theogre
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SEP 16, 11:43 PM
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This board has 3(84 is 4) functions: Speedo, Odo and Trip counters, and divide/drive for ECM and Criuse. (84 Fiero Is the Cruise module too.)
Odo and Trip works Then Speedo is dead.
ECM would trip DTC at "random" if VSS or Divider don't work.
Odo and Trip is Stepper Motor drive.
Speedo Is Not. Speedo "Gauge" is about same as Tack, Fuel, and Temp. Closer to Tack because of driver chip etc on the board.
Speed "dead" then try carefully loosen and tighten the speedo nuts a few times. 4 "studs" and nuts are electric parts that get loose, crap on them, etc.
These stamped nuts aren't very tight to start w/ so don't torque them down hard like normal hardware.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave[This message has been edited by theogre (edited 09-17-2020).]
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