Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Speedo problem 4/4

Hello, my speedo won’t go beyond 15mph. Does anyone know how to fix this? On startup the speedo does a full sweep so it doesn’t seem to be mechanically jammed. It’s a 1998 4/4 zetec.
Thanks, Chris

Maybe release the handbrake ??

Hi Chris
As a start in determining the problem, try a short drive of a known distance and check if the odometer clocks up the distance run correctly.

Regards Tony

Thanks for your reply Tony.
I’m glad you mentioned that. I’ve just done a 2 mile journey and the odometer shows I’ve driven 12 miles.

Since it does a sweep at startup, it's an electronic, not a mechanical cable driven instrument. The issue is likely with the sending unit. Is it a Smith's or VDO?

It’s a VDO. I think the sender is at the rear of the gearbox? As it involves some dismantling to get at I’ll probably take it to a dealer to fix it.

Hi Chris

From what you have observed it seems to me to point to the instrument or its power supply. The speed reading is under reading beyond 15 mph and the odometer is over-reading by a factor of 6 i.e. 6 x 2=12. Make sure the button at the bottom of the instrument is not jammed in i.e. permanently pushed, if it is the instrument would be in calibration mode every time you turn the ignition on.

Assuming the button mention above is not jammed, with the ignition on does the display change from total mileage to trip mileage and back when you press it. Also is the word “test” shown in the display when the pointer is sweeping across the full range on switch on.

I have an installation document for this speedo with lots of info about it. I can't find a way of attaching a file to a post or a pm in Talk Morgan but if you send me a pm with your e-mail address I can send you a copy.

Regards Tony

Thanks Tony. PM sent.

Hi Chris

My car is a 1999 4/4 fitted with a silver top Zetec so is probably very similar to yours.

Have a look at this link for my simple speedo tester https://www.talkmorgan.com/ubbthrea...er-not-working-on-2008-plus-4#Post817814


See also this link to a simple sensor check https://www.talkmorgan.com/ubbthreads.php/topics/819367/re-1998-4-4-seater-speedo#Post819367




Regards Tony

Thank you, Tony. The information you sent is very interesting. You have done a lot of research about this problem. It makes me wish for the old days when there was just a mechanical cable to worry about.
Regards, Chris