Good day,

See if you can figure this out.

The speedometer/odometer in my 85 740 has been flaky for some time.
Sometimes works sometimes doesn't. Mostly works.

No particular rhyme or reason but it tends to fail intermittently.

I could make a case for heat, as it seems to fail mainly in warm
weather.

Checked the pickup connection on the rear end. Seems OK.

Pulled cluster, nothing obvious there.

Have not checked ground in trunk (boot).

Recently, I had some welding done on the car. At the time speedo was
not working. Ground was disconnected from the battery to prevent
damage to electricals during welding (SOP?)

Reconnected battery and voila, speedo works!

A bit later, speedo stopped. (Of course it was a warm day and I was
going rather fast).

He say's hmmm, I wonder?

Disconnected battery and sure enough, speedo began to work.

Thoughts?

jimB

"jimb" <jiXb@Xvd.Xv.coX> wrote in message
news:jnpb43192jv50vfmaemki619inkoobri87@4ax.com...
> Good day,
>
> See if you can figure this out.
>
> The speedometer/odometer in my 85 740 has been flaky for some time.
> Sometimes works sometimes doesn't. Mostly works.
>
> No particular rhyme or reason but it tends to fail intermittently.
>
> I could make a case for heat, as it seems to fail mainly in warm
> weather.
>
> Checked the pickup connection on the rear end. Seems OK.
>
> Pulled cluster, nothing obvious there.
>
> Have not checked ground in trunk (boot).
>
> Recently, I had some welding done on the car. At the time speedo was
> not working. Ground was disconnected from the battery to prevent
> damage to electricals during welding (SOP?)
>
> Reconnected battery and voila, speedo works!
>
> A bit later, speedo stopped. (Of course it was a warm day and I was
> going rather fast).
>
> He say's hmmm, I wonder?
>
> Disconnected battery and sure enough, speedo began to work.
>
> Thoughts?
>
> jimB
>

The circuit boards in these use some sort of really poor solder, it
crystalizes and cracks with age. I've had good luck fixing them by removing
as much existing solder from each joint as I can and flowing in some new
quality rosin core tin/lead solder.

AFTER PULLING MY WIFES SPEEDO APART I feell the issue could be a poor
connection as in a loose and or corroded connection.My wifes speedo is 4 klm
per hour faster than it was and no more speeding tickets.Here 3 klms over
and its $135.00 au dollars fine even if the police equiptment is untested or
faulty ..THATS 1.8 miles an hour .I noticed poor contacts such as earth and
loose clips and such which could be your problem .







"jimb" <jiXb@Xvd.Xv.coX> wrote in message
news:jnpb43192jv50vfmaemki619inkoobri87@4ax.com...
> Good day,
>
> See if you can figure this out.
>
> The speedometer/odometer in my 85 740 has been flaky for some time.
> Sometimes works sometimes doesn't. Mostly works.
>
> No particular rhyme or reason but it tends to fail intermittently.
>
> I could make a case for heat, as it seems to fail mainly in warm
> weather.
>
> Checked the pickup connection on the rear end. Seems OK.
>
> Pulled cluster, nothing obvious there.
>
> Have not checked ground in trunk (boot).
>
> Recently, I had some welding done on the car. At the time speedo was
> not working. Ground was disconnected from the battery to prevent
> damage to electricals during welding (SOP?)
>
> Reconnected battery and voila, speedo works!
>
> A bit later, speedo stopped. (Of course it was a warm day and I was
> going rather fast).
>
> He say's hmmm, I wonder?
>
> Disconnected battery and sure enough, speedo began to work.
>
> Thoughts?
>
> jimB
>

The speedo in my 92 740 was intmt. for a couple of years. Installing a
new inst. cluster did not fix it. The fix turned out to be running a
new two-conductor cable all the way from the speedo to the sender
unit. Has worked perfect since.



On Tue, 15 May 2007 20:53:58 +1000, "John Robertson"
<johnnr@optusnet.com.au> wrote:

>AFTER PULLING MY WIFES SPEEDO APART I feell the issue could be a poor
>connection as in a loose and or corroded connection.My wifes speedo is 4 klm
>per hour faster than it was and no more speeding tickets.Here 3 klms over
>and its $135.00 au dollars fine even if the police equiptment is untested or
>faulty ..THATS 1.8 miles an hour .I noticed poor contacts such as earth and
>loose clips and such which could be your problem .
>
>
>
>
>
>
>
>"jimb" <jiXb@Xvd.Xv.coX> wrote in message
>news:jnpb43192jv50vfmaemki619inkoobri87@4ax.com.. .
>> Good day,
>>
>> See if you can figure this out.
>>
>> The speedometer/odometer in my 85 740 has been flaky for some time.
>> Sometimes works sometimes doesn't. Mostly works.
>>
>> No particular rhyme or reason but it tends to fail intermittently.
>>
>> I could make a case for heat, as it seems to fail mainly in warm
>> weather.
>>
>> Checked the pickup connection on the rear end. Seems OK.
>>
>> Pulled cluster, nothing obvious there.
>>
>> Have not checked ground in trunk (boot).
>>
>> Recently, I had some welding done on the car. At the time speedo was
>> not working. Ground was disconnected from the battery to prevent
>> damage to electricals during welding (SOP?)
>>
>> Reconnected battery and voila, speedo works!
>>
>> A bit later, speedo stopped. (Of course it was a warm day and I was
>> going rather fast).
>>
>> He say's hmmm, I wonder?
>>
>> Disconnected battery and sure enough, speedo began to work.
>>
>> Thoughts?
>>
>> jimB
>>
>