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Registered
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Odometer issues but it's been rebuilt
So my electric speedo's odometer & tripometer doesn't work and I got it sent to get repaired. I believe they repaired it successfully as the mileage went up and the tripometer had increased as well since I took it out.
I reinstalled it and seems like the issue hasn't been resolved. I've compared the wiring on the speedo to other pics here and it looks correct. Don't think it's the motor within the speedo as mentioned, the mileage did increase by after it was repaired. Read there is a sensor near the transmission but that controls both speedo and odo so that probably isn't it... Not sure what else to try..
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1975 Aubergine 911S - Barney "When that doesn't work, and it doesn't quite often, it's as though your face has been amputated." - Jeremy Clarkson |
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09-25-2018, 05:04 AM
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Member 911 Anonymous
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So the shop tested it and on the bench it worked?
On you car it is not working? Get under the car and remove the Sensor "puck" and pass a magnet over it quickly, several times and have a help observe the speedo. Ask if it pulses, if not then you have a short along the line to the speedo. On the tunnel, before the coupler access, there is where the sensor is connected to the wiring to the speedo, remove it and place a DVM on the wires and do the pulse test, if you get voltage after passing the puck sensor is good. Now check from that connector to the speedo connections to see if there is continuity on the wires to check for a short. Check your connectors at the wires are clean and polished and tight, not loose on your speedo. This will narrow down the culprit. Break a Leg Brother!
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'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
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09-25-2018, 09:05 AM
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Registered
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if Im reading it correctly it sounds like your ODO and Trip ODO are not working right but your Speed readout is. If thats the case its not the sensor as there is a single one that drives the whole unit. The ODO/Trip is computed by integrating speed across time (this drives the motor that spins the odo).
The most common problem on these is the little drive gear either shredding, falling out of place, or in my case the bracket that held the motor in backed out. You will need to pop the speedo open to check all these. The gear is plastic and has a habit of tearing up pretty easy. Some will say never reset your trip odo as that can cause it to shred. There is a small screw that holds the odo motor drive bracket down, for me the screw loosened and the motor backed up a bit. This caused it to spin fine but not make contact with the ODO its self. All i needed to do was tighten the bolt. Its possible some of the circuitry is toast but that is a bit harder to check without the proper tools. If you have a multi meter you can check the resistors, with a +12V supply and a frequency generator you can bench test the unit. if memory serves the unit takes a +-12V square wave signal between 0-300Hz to drive the input if you want to try bench testing. Regards Dave
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'78 911SC Targa (Back In Action!) '00 996 Carrera (New kid on the block) '87 944 (college DD - SOLD) '88 924s (high school DD - Gone to a better home) |
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09-25-2018, 03:59 PM
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Barney
Marble Grey
