Speedo Chestnut, with a manual-auto twist

Has he tried getting an instrument pod out of a manual car rather than an auto?

just run a test on the feedwire from the diff to the back of the instrument cluster. close inspection should be able to tell you which one. if the lines good its either the diff sensor, or the guage.

Do the above though, and check the diffconnection first. the wires are very exposed to all weather etc, and are often the cause of such an issue.

Could there be any possible connections loose anywhere, or any connections connected wrongly. If a lot of activity has been going on there you might have inadvertantly overlooked something basic, and may therefore be looking in the wrong place. It might be worth going back to the begining and double checking every wire and connection that has been touched.

I have had this happen to me, and it was the simplest fix.

 

I have to report it, I feel like I've just discovered El Dorado! . . . ie. IMy 635 now has a speedo!

Nah, must say it again, "I have a speedo"!

4 entire "instrument pod" rebuilds; untold hours; battery replacements; wire tracings; fuse replacements. . .

But, errr, I now have a speedo!

Am I impressed? Nah, not much!  

I think I'll go for a drive around and around town, just to watch the needle move!

Thanks all for your assistance along the way.

cheers, Graeme

Ultimately, it was a simple lesson learnt. ie. each one of the secondhand replacements had battery leak damage, and both myself and the mechanic kept dismissing the fact 3 entire replacements could be similarly damaged. Because the car is an auto to manual conversion, many assumptions were thus made along the way that the conversion was the problem, or something connected with that. But, in the final wash, it wasn't. Twas simply a matter of going with the obvious; but being inclined to think the obvious was too simple, we gave ourselves more grief than we should have.

Thanks Paul. One thing I might add, just picking up on "Brucey"'s point above, is that tracing everything back from sensor to dash, and then forward from dash to fuse box ended up being a tedious, but useful, exercise. At one point the car began running like an old mule, and we traced that to having stuck in a dubious relay when checking/replacing things, for example. Useful for future reference, I realised. Equally, I now have dashboard lights and all the check lights work, as does the tacho etc; the condition of the SI Board, and the servicing "behind the plastic" pretty much pointed to the fact the final, working, set of clocks would ultimately work; whereas the other sets we (innocently) tried, combined various degrees of "not-working-ness!". Whether that is a tip re: if everything works speedo will work, is up entirely debatable, I guess. But in this case the fact everything was in order was a good indication that speedo was going to work. So all the time spent trying to build bits back together into a fully functional pod was not as productive as simply looking for a good complete pod.