paalw

Hi,

I just posted another thread about what gear to order for my odometer that has been standing still for some years. I hadn't opened it yet, and was adviced to open it to be sure to get the correct thoothed one.

So i opened it up and to my surprise all the gears seems fine and intact. There is what seems like a little chip on the "screw" coming from the motor(maybe it is by design, I don't know), but it doesn't seem to have an impact on operation. I have rotated the screw by hand both ways and the operation seems very smooth, counters(both total and intermittent of course) were turned 1km manually without issues.

So, any ideas where the problem might be?

Bilal928S4

The problem could be that the odometer is not getting any signal. Just a WAG.

paalw

Thanks.
I guess what i'm wondering is, are there any known problems, or things to test, regarding my issue?

James Bailey

the same signal drives the odo and speedo ..the silver unit below that white worm gear is an electric motor... not sure how the electric pulses from the magnetic switch gets converted into turning that motor

Hai gebissen

Just to confirm...your speedometer does work?

paalw

Yes

GerritD

Problem could be :

- too weak pulse. Solution : see my post
https://rennlist.com/forums/928-foru...nal-boost.html

- problem with internal powersupply unit of the speedo. This was the case with my speedometer. Repair cost about $120

kr
Gerrit

Ian S4

Not likely to be a weak pulse from the sender. The speedometer and the odometer are both driven from the same integrated-circuit. Since the speedometer is working, that IC must be getting a good signal.

The motor is a stepping-motor, with three wires going to the printed-circuit board. Make sure these wires haven't detached. Also, you could check the resistance of the motor windings. I have one right here...I read 76 ohms from the yellow to each of the greens, and 152 between the greens.

Ian

medipedicman

What year is your car?
I have the pcs from a OB cluster(including the speedometer) in a box somewhere if you decide you want to try to swap or take parts.

paalw

Hi, i got 76 from one and 55 from the other, and 130 between the greens. But don't know what to read of that. Suspicious?

Is there a way to test operation of the electric motor?

Btw, car is a 1983 Euro S (metric).

Ian S4

You can test the motor by alternately grounding each of the greens (with power applied, there should be battery voltage on the yellow). It should turn a little each time. Only ground one green wire at a time.

Ian S4

55 ohms does sound a little suspicious. That would cause one of the output stages to draw almost 50% more current than the other, which could, after a few years, cause premature failure of that output.

What part number do you see on the top of the chip? Should be SAY115 or UAF2115.

syoo8

Paalw,

Does the odometer 'click' when driving?

paalw

I see. Any chance of altering the resistance? I guess not?
Chip is SAY115X.
Will a small 12v "smoke detector battery" be ok to test operation?

Syoo8, I haven't heard or seen any clicking while driving, no.

Ian S4

If that battery can provide at least a couple of hundred mA, it will be ok.


Ian