Speedometer issue

Possible the capacitors in the gauge are bad? They get old and leak or overheat. This is a known problem for speedos but more specific to the RPM or Tacho gauge.

Spaceresearcher
Hello Miyagi,
    As a MK1 MR2 enthusiast and having had a speedometer issue myself not too long ago I thought I'd put forward an idea for you.
 
With what you have tested and verified to be working it's highly possible that the speedo cable to gearbox is possibly not connected correctly.
 
I had an issue with mine where the speedo was jumping around ever so slightly and what I found was the following
 
The connection to the gearbox must be installed with the speedo cable indenture nodule lining up with the connection in the gearbox other wise it will most certainly not work correctly.
 
If that's correct then check that you have installed the connection down firm and tight ALL the way.  Mine once managed to wind it's way loose.  Tightening it up and checking verified  it worked just fine.
 
Failing these 2 check points, I'd be pulling out the speedo cable to check that it's not fraying etc as this will most certainly give you mixed and intermittent results.  Sadly they can wear out, especially if not installed correctly.  On that note, be sure that your speedo cable is routed as per Toyota standard manufacture.  Failure to do so can also lead to strange Speedo issues.
 
Hope one of these fix it points works and that you have your MR2 working perfectly as it always should be.
 
Drive on and continue to enjoy your MR2 Miyagi,
Sean.
(Spaceresearcher)
 

His is electronic so the cable doesn't exist. It has a sender on the Gearbox and uses purple or purple with white wires to send the signal to the gauge then back to the ECU.

Gents,
 
I hope that I've use the correct area to reply as I can't locate a reply button for individual responses.
First and foremost I appreciate all your prompt replies.
 
GDII
Thankyou. Initial attempt to rectify speedometer issue was to replace all associated damaged capacitors by a very knowledgeable MR2 friend.  Unfortunately issue continued.
 
SPACERESEARCHER
Thankyou. I'm operating an electronic speed sensor so no mechanical cable.
 
FALCON
Thankyou.  The fluctuation of the needle is inconsistent and indication of speed is also incorrect.  I should have also  mentioned that the vehicle originally had a mechanical speed sensor which upon removing I found that the plastic gear sub-assembly on shaft was damaged.  Therefore I decided to replace it with a used serviceable electronic speed sensor plastic gear 30-35, hence installing individual wires (with much knowledgeable assistance from my MR2 friend).  Yes, totally agree regarding the little load to drive the speed sensor should it originally was electronic sensor (which unfortunately I overlooked to mentioned that it use to be a mechanical drive) so damage may have already been done to the Blue plastic drive gear.  I can only assume that removing the gearbox could not be achieved whilst in the vehicle.  I appreciate your concern regarding working safely as I can assure you that I have place additional rated stands beneath the vehicle and on level footings.
 
Many thanks and have a great day.

Engine out = PITA, so just a couple of thoughts:
 
I have recently fitted a 7" Android head unit that apart from all the other stuff on it also has a good reliable installed GPS program, and while driving I mostly have that app running so I can use the speed indication on it.
IMO it is probably easier to read than the OEM speedo that I now hardly ever look at.
The GPS is more accurate anyway, important when setting my cruise control so as not to exceed the speed limit in strict enforcement areas.
 
Another cheap, and simple alternative to the OEM speedo might be one of the better 'heads up units' (HUD).

Reddtarga
Thankyou for your response and suggestions. I'm currently still working on the vehicle in preparation to get it registered and yes I've ask the question regarding the installation of a GPS speedometer device, unfortunately the reply was NO.  Should I have to remove the box to repair the speedometer drive gear I'll would much prefer not having to remove the whole motor and gearbox assembly.

miyagi
Should I have to remove the box to repair the speedometer drive gear I'll would much prefer not having to remove the whole motor and gearbox assembly.

Obviously the advantage of doing it that way is that you don't need to disconnect the wiring loom, coolant, and  A/C pipes. A PITA to put all that back, especially re-bleeding the system etc.
 
But to remove the trans with the engine still in the car if you want to do the work yourself you will need to read up on it since it can be a tricky job, depending on what facilities you have. 
 
Things to consider:
First how to safely support the car, then after removing the rear X member suspension and drive shafts, you'll need to work out how to safely support the engine on the passenger side, since you will only have one engine mount left on the driver's side.
IMO a block of wood under the sump on a trolley jack is a risky operation; if it slips - disaster, although I'm sure people have used it. I solved this problem by fabricating a bar across the strut towers so I could securely support the engine from above.

The whole assembly will also need to be lowered slightly on the passenger side so the trans. will clear the chassis to get it out, and transmissions are heavy suckers so you'll need something to raise/lower it unless you have been spending a lot of time at the gym.
I had the use of a car hoist for this job as well as an engine crane, and trolley jack.
Even so it was still a tricky operation, but quite feasible.
 

TonyMR2,
I am in Perth, Western Australia and very much appreciate your offer, however I have ordered and waiting for the arrival of the gear driver and follower.  Process of elimination should do the trick and hopefully I will have the solution in the near future.  Many thanks for your feedback, cheers Miyagi.