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speedo issue

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Old Aug 18, 2017 | 01:58 PM
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79 vette, speedo does not work...took speedo out and checked ok, checked both cables, ok, power at transducer, ok....replaced transducer still no speedo....trans. was rebuilt and that area for speedo ok....thinking of going direct gage to trans and eliminating cruise..need a speedo
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Old Aug 18, 2017 | 02:53 PM
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You can test the speedo cable by attaching a drill onto the end of them, an checking if the speedo works. Find where it stops working and that's where you problem is. It may be the gears in the transmission.
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Old Aug 19, 2017 | 07:31 AM
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Its almost always the Cruise Transducer. It has a plastic link for the cable from the trans to slide into. This will strip out and then there is no speedometer. I have gone through several on my 78.
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Old Aug 19, 2017 | 09:54 AM
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after I ckd everything as mentioned in my post the speedo would after maybe 50 mi suddenly work and accurately... then some time later stop...try starting several times, maybe working once and then stop...did you notice this issue .
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Old Aug 19, 2017 | 10:38 AM
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That could be the cable from the trans to the Cruise box. May need lube. I think when the transducer fails the speedometer will start jumping back & forth or maybe even like what you say you have to get to a high speed for it to work.
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