Intermittent Odometer

[patman]

My odometer and trip meter are only occasionally working. Also, the tach is inoperable. I have ordered a new tach amp.

Is the most common problem a gear, cable or something else? Is the odometer attached to the transmission? Is there any relationship between my tech problem and the odometer?

Thanks for any insight.

Does the speedo still work when the odo does not? The SD's do not use a cable, they use an electric sender.

[its_snowing]

i have the same problem. sometimes my odometer is dead on, and other time it runs about 60%-65%. the speedometer, however, is always working fine. cant quite figure out what the issue is. im think that maybe a gear is occasionally slipping.

[vstech]

the search at the top will help tons on these two different problems.
on the tach search for cigarette butt and tachometer. on the odometer, just search for SD Odometer.
my tach quit on my SD and I think it is ground issue, cause it is wierd... and an amp did not help.
the odo could be gear or shaft related, not too difficult to take apart. diesel giant's site is good for a nice pictorial on this.
John

[JimmyL]

Also, when you have 2 cars in your signature it helps to tell us which one you are referring to. Your 2 SD's have different setups....... (excellent to have a sig filled out, though )

**we're assuming the W126 though**

[patman]

Yes, I noticed this morning when I started reading the responses, I forgot to state which one. It is the 79 SD W116.

The speedo works fine.

I am worried about the possible grounding problem if its not the amp. I tried a tach amp I thought was working and it didn't fix the problem. That's when I broke down and ordered a new one.

I tried the search and couldn't find the help I needed. I did find one thread that talked about cables to the transmission. That is why I was questioning the cable.

Thanks for the responses.

[patman]

The odometer appears to work most consistently in the morning. It has never worked on the way home from work.

If the odometer is eletronically controlled, where does the signal come from? Is it the tach amp?

[patman]

I just wanted to end the discussion on my intermittent odometer. I finally found some articles about a part that slips. I have included 2 of the links that I thought were very interesting. I plan to use them as I tear apart my instrument cluster and figure it out.

BTW, any advice on lubricating the speedometer cable on a 79 300 sd?

http://dieselgiant.com/repairyourodometer.htm
http://www.peachparts.com/shopforum/showthread.php?t=90607&highlight=odometer