S3C Speedometer over-reading by x2
Discussion
Having bought the car a couple of years back knowing the speedo was showing exactly twice what the car was actually doing (and obviously clocking up double the mileage), I've had enough.
The prevous owner used this hallowed forum to try to resolve the issue, but was ultimately unsuccessful. I've re-visited these posts and tried to to grips with the problem. So far, I have been unsuccessful too.
I've tried using a voltage regulator (a "TS7805" - as per a previous suggestion) in the pulse circuit, but it made no difference at all.
Would it be possible to get a gearbox sender unit that sends out half as many pulses as the unit currently fitted so that the speedo reads correctly?
(I'm only currently doing about 3000 miles per year - 6000 on the speedo. I'm limited to 10k on the insurance, but it won't take much to theoretically put me over the mileage limit).
The current Ford sender unit has the following codes on it:
95GB-
9E731-CA
D25KE
602 120
The previous owner gave me a brand new speedo unit bought from David Gerald. (Labelled S2/S3). This doesn't appear to work - at least not with this sender.
He also gave me another sender with the following code:
95GB-
9E731-EA
D25KE
602 152
This doesn't work with either speedo.
Any help or assistance would be much appreciated.
The prevous owner used this hallowed forum to try to resolve the issue, but was ultimately unsuccessful. I've re-visited these posts and tried to to grips with the problem. So far, I have been unsuccessful too.
I've tried using a voltage regulator (a "TS7805" - as per a previous suggestion) in the pulse circuit, but it made no difference at all.
Would it be possible to get a gearbox sender unit that sends out half as many pulses as the unit currently fitted so that the speedo reads correctly?
(I'm only currently doing about 3000 miles per year - 6000 on the speedo. I'm limited to 10k on the insurance, but it won't take much to theoretically put me over the mileage limit).
The current Ford sender unit has the following codes on it:
95GB-
9E731-CA
D25KE
602 120
The previous owner gave me a brand new speedo unit bought from David Gerald. (Labelled S2/S3). This doesn't appear to work - at least not with this sender.
He also gave me another sender with the following code:
95GB-
9E731-EA
D25KE
602 152
This doesn't work with either speedo.
Any help or assistance would be much appreciated.
It sounds like you have the wrong sender unit. I don't know if the Ford ones work on the same principle as the Rover units but if they do then there are two types, 4-pulse and 8-pulse. On the face of it, you may have an 8-pulse fitted instead of a 4-pulse. Your other option is to send the new speedo head and your spare sender unit to somewhere like Speedycables and get them to match one to the other.
Thanks for the information guys, much appreciated. I may go for an AB-type sensor, but that one on ebay is too expensive to take a chance on. Maybe I'll keep a look out for one a bit cheaper....or a second hamd one.
I'm not convinced the 'new' speedo I have works at all to warramt sending it off. I tried it with the current sender and it went backwards and stayed at a constant reading even at different wheel speeds (back of car jacked up with wheels off the ground). If I knew it worked okay, I would sell it to help pay for a sender.
Such an awkward job to sort. Centre dash out, steering cowl removed, column lowered, speedo removed, taking care not to upset all that bloody fragile wiring...and all the while needing stick thin fingers and hands to get to stuff. Nightmare. Not a job I want to do too often. All put back together at the moment while I humbly look for amswers from you Gurus.
Thanks again.
I'm not convinced the 'new' speedo I have works at all to warramt sending it off. I tried it with the current sender and it went backwards and stayed at a constant reading even at different wheel speeds (back of car jacked up with wheels off the ground). If I knew it worked okay, I would sell it to help pay for a sender.
Such an awkward job to sort. Centre dash out, steering cowl removed, column lowered, speedo removed, taking care not to upset all that bloody fragile wiring...and all the while needing stick thin fingers and hands to get to stuff. Nightmare. Not a job I want to do too often. All put back together at the moment while I humbly look for amswers from you Gurus.
Thanks again.
TVRees said:
How about this....
http://tvr-parts.com/tvr-parts/part-details/tvr-s2...
Hmmm. That's tempting...http://tvr-parts.com/tvr-parts/part-details/tvr-s2...
Thank you.
TVRees said:
How about this....http://tvr-parts.com/tvr-parts/part-details/tvr-s28f-10010/speedo-transducer
Blimey! That's 1/3rd the price of one for a V8S.v8s4me said:
Blimey! That's 1/3rd the price of one for a V8S.
JoeEveryone knows that you V8 guys have wads of cash, unlike us poor V6 people.
Barkychoc said:
It's fairly easy to divide a digital 5V signal by two - I haven't dabbled for a long while but off the top of my head get a binary counter chip, put the speedo pulses into the clock input, and use the lowest bit output to the speedo.
Sorry Chris, but I'm afraid you lost me after the word "digital"...As a suggestion use one of these - very cheap. Use the Qa output to halve the frequency.
http://www.mercateo.co.uk/p/2811-74LS93/IC_digital...
http://www.mercateo.co.uk/p/2811-74LS93/IC_digital...
Speed Matters | S Series | Top of Page | What's New | My Stuff