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Odometer and tripometer not working
I removed the instrument cluster to fix the odometer, thinking it is the gear that has broken apart. I purchased one from Roger. Well, I dug into the cluster and all the gears are intact. Any ideas what else it could be?
Thanks Mike P
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1988 Porsche 928 S4 (rescue) |
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08-04-2012, 06:50 PM
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Can the servo motor be benched tested?
Thanks. Mike P
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1988 Porsche 928 S4 (rescue) |
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08-05-2012, 08:35 AM
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If it's not the gear, then it can be the PCB connectors, PCB itself, grounds, connector in the spare tire area or the sensor mounted on the rear diff.
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1981 Porsche 928 "Euro" Auto Gunsmoke Metallic Flat - Black Interior 1983 Porsche 928S "US" Auto Light Bronze (Copper) Metallic - Brown Interior **SOLD** 
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08-05-2012, 10:07 AM
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Registered
Join Date: May 2010
Location: Magnolia TX, just north of Houston
Posts: 369
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Quote:
However, you might want to check for binding in the worm gear to the driven gear, as well as the odometer or trip indicators binding up and locking of the mechanism. In one case I discovered the new gear was just a bit bigger than the original gear, but I found that out after I reinstalled the pod and drove a couple of hundred miles....then it stopped. A washer "shim" under the foot of the motor provided enought freedom for the gear mesh and it has worked for 5000 miles since. Perhaps your gear was replaced by a PO with one of these that binds up, ot it may just have locked up in the indicators themselves....
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1956 Intermeccanica 356 Speedster (sold),1957 Intermeccanica 356 Speedster (sold),,1985.5 Porsche 944 (sold),1955 Thunder Ranch 550 Spyder (sold), 1955 Outlaw 356 Speedster (currently in build out), 1984 Porsche 928S (White), 1984 Porsche 928S (Red) |
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08-05-2012, 10:18 AM
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MPDano, Thanks I have cleaned all the grounds in front of the car. I did not think about the rear. I will also check the sensor. When I replaced the filter and gasket for the transmission I noticed a wire back there that was bare. I fixed it but did not notice where it went. It might be part of the sensor. I am going back under there and check the sensor. Thanks
Tmpusfugit, I can move the worm gear with my finger and move it enough to change the mileage. I don't know if my finger get a little grease on it but, it feels like it binds a little. Can you put a 9v battery on the leads to see if it turns or will that burn everything up? Thanks for the help. Mike P
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1988 Porsche 928 S4 (rescue) |
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08-05-2012, 11:51 AM
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Petie3rd
Join Date: Jul 2000
Location: Philly PA
Posts: 4,528
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if you take a look at the gear that was replaced you may find one of the teeth has a little bit extra flash from the molding process,
The cure is to trim the gear teeth, I have found this issue on a few replacements. The extra flash causes the gear to have hi spot and thus bind and stop the mechanism from turning Otherwise the motor for the speedo could be bad disconnect the wires and test it with a 9volt battery if it wont turn then you found the issue
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^^^ Stan ^^^ 2019 BMW K1250 GS 2016 HD RK 1988 S4 Auto , Elfenbein Perlglanz, Pearl Gray 1982 5sp Met black and tan sport seats |
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08-05-2012, 08:54 PM
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I have disconnected the motor. It has two green and one yellow wire. I am not too good on the electrical side. How do I test the motor?
I took a resistance meter and I am getting a reading with touching all three leads. Is that an indication the motor is bad? Also, if the motor is bad, are there motors available? Thanks. Mike P
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1988 Porsche 928 S4 (rescue) |
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08-06-2012, 04:13 PM
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Not to threadjack, but is gear failure inevitable on these cars? Is this something I should add to my next order just to have on hand?
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George in Indiana 928 Weissach #153 Cayenne S |
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08-06-2012, 05:29 PM
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# 153
