THE ROVER SD1 FORUM

rod baker · SD1 User Joined: 10 Feb 2008 Posts: 37

hi all does any body know how i can test my speedo as i am not sure if it working it is hard to get bit here to play with and it expensive so i want to be sure first
rod

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1982 sd1 se 3500 runs reasonable lots of electrical gremlins was real cheap and lots of fun

KwS · Posted: Wed Feb 20, 2008 2:46 am Post subject:

if you dont have a haynes manual, i seriously suggest getting one. Its seriously an SD1 owners bible. Smile

rod baker · SD1 User Joined: 10 Feb 2008 Posts: 37

kool i do have a haynes manual and most of the time it say how to remove and refit, not how to test.
On most cars i would try a different part but there is only one other sdi here and he wouldnt lwant me to put a spanner near it

so far i have been told the speedo transducer is an ac generator and as the speed increases so doea the output which is measured bythe speedo
rod

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1982 sd1 se 3500 runs reasonable lots of electrical gremlins was real cheap and lots of fun

ramon alban · Posted: Thu Feb 21, 2008 2:32 pm Post subject: Re: HAYNES MANUAL

rod baker wrote:

so far i have been told the speedo transducer is an ac generator and as the speed increases so doea the output which is measured bythe speedo
rod

Rod the output from the transducer is a series of pulses proportional to the speed of the car.

The speedo reads the frequency of the pulse and converts them to the speed reading.

I do not know how the electronics does this but to test the speedo you could try the following.

Jack the rear wheels of the car off the ground and set the car idling in gear.

There should be an output signal from the transducer which would be measyurable with a DC voltmeter btween the signal wire and EARTH.

Increase the road speed and the DC meter will show an increas in voltage because there are more pulses taking place for it to sense.

If you have an output signal check that it exists all the way up to the speedo.- if it disappears then that would indicate a break in the wiring or a connector issue.

If the speed then reads ok by fixing such a problem then - job done.

If not then it may be the speedo at fault.

If you have an electronics friend with a pulse generator the it would be possible to emulate the input signal to test the speedo.

Also - bear in mind that the same speed signl drives the trip computer and if the trip computer is working and calculating ok then the signal must be ok and the speedo would be broken.

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Ramon

gogs · Posted: Fri Feb 22, 2008 1:03 am Post subject:

Hi a wee bit more info- i think the plug after transducer should be ignition fed from a white wire that joins at lh inner wing multiplug [also feeds coil]
other wire possibly black/red after transducer plug. + also goes to lh inner wing-[easy place to test continuity down+ back ]Sd1 wiring can get pretty brittle around gearbox+ often breaks/shorts.If you are short of a transducer then i can easily have a look in shed for one .not dear secondhand .

rod baker · SD1 User Joined: 10 Feb 2008 Posts: 37

hi guys thanks heaps for he responses i have bought from ebay a s/h transducer and i have found that the both wires at the transducer were live .
traced this to the dash wiring that was for the trip computer and had been pluged together will fit the transducer tomorrow and will see
hopefully it has not hurt the speedo
sorry for a alow update but my other favourite car that i drive is a 38 chev hot rod and it got backed into by an old ute. he managed some where in the vacinity of 5000$ au in repairs but i cant get parts easily

rod

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1982 sd1 se 3500 runs reasonable lots of electrical gremlins was real cheap and lots of fun

kiwi_sd1 · Posted: Sun Mar 09, 2008 10:00 am Post subject:

ouch

I hope you have insurance, plus a panelbeater you trust...