Odometer
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Rennlist Member
Joined: Jan 2010
Posts: 85
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From: Stafford VA
Odometer
Just replaced the gear in the speedometer assembly. Everything seemed to go back together correctly and the gears meshed well before putting the dash/pod back together. However... odometer is still not working. What should I look at next?
Thanks,
Steve
88 S4 Auto
Thanks,
Steve
88 S4 Auto
Nordschleife Master
Joined: Apr 2003
Posts: 9,601
Likes: 39
From: Abbotsford B.C.
Open it back up and there is the small motor with the worm gear on it. If that motor fails then the odometer will stop working.
I also experianced a new failure for the speedo/Odo the other day. I had a resistor burn up so to speak on the little board on the back of the speedo. Thankfully I had another slightly damaged speedo that I was able to steal it off of and I just unsoldered the two wires for the speedo and soldered them into the new board.
As well on the PCB on the back of the cluster there are 4 pins which transfer the signals to the speedo. They then have rivets beside them. I always take small jumper wires and solder from the back of the pin to the jumper, and then onto the pcb. This ensures that the fix will last. And that the speedo will work right from the start.
I also experianced a new failure for the speedo/Odo the other day. I had a resistor burn up so to speak on the little board on the back of the speedo. Thankfully I had another slightly damaged speedo that I was able to steal it off of and I just unsoldered the two wires for the speedo and soldered them into the new board.
As well on the PCB on the back of the cluster there are 4 pins which transfer the signals to the speedo. They then have rivets beside them. I always take small jumper wires and solder from the back of the pin to the jumper, and then onto the pcb. This ensures that the fix will last. And that the speedo will work right from the start.
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Joined: Jan 2003
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From: Double Oak, TX
I have done a lot of these and in the begining this happened after I had replaced the pod - GRRRR.
Often the small parts of the disintegrated gear get lodged in the existing gear mesh.
Blow out with compressed air and make sure no bits are left.
If that does not make a difference refer to the above post from Lizard.
Often the small parts of the disintegrated gear get lodged in the existing gear mesh.
Blow out with compressed air and make sure no bits are left.
If that does not make a difference refer to the above post from Lizard.
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Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Instructor
Joined: Jan 2002
Posts: 163
Likes: 1
From: Southern California
The odometer and speedo are driven by an integrated-circuit, UAF2115, "Speedometer and Mileage Indicator", made by ITT.
The odometer motor is driven by pins 2 and 12 of this IC. When the rear wheels are turning, you should see pulses on both of these pins. If you see the pulses but the motor does not move, then the motor is busted, or jammed. If you don't see the pulses, then the IC is likely fried, or the windings are open circuit.
This test is much easier to perform if the speedometer is removed from the car, and an external signal is used to fake the signal from the sender on the differential unit.
The odometer motor is driven by pins 2 and 12 of this IC. When the rear wheels are turning, you should see pulses on both of these pins. If you see the pulses but the motor does not move, then the motor is busted, or jammed. If you don't see the pulses, then the IC is likely fried, or the windings are open circuit.
This test is much easier to perform if the speedometer is removed from the car, and an external signal is used to fake the signal from the sender on the differential unit.
Drifting
Joined: Apr 2002
Posts: 2,070
Likes: 34
From: Hendersonville Tennessee
When I replaced my gear, it quit working fairly quickly, so I shimmed in a few thin washers so there wasn't any 'slop' in the entire gear assembly. It has worked flawlessly ever since.
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