No output from VSSB to speedo -7427 ecm

Changeover to 4l60e & f.i. on olds 403 w/95 c1500 truck bjyk 16197427 ecm. I have a factory scan tool & a digital oscilloscope.The B+& B- check good. The speed sensor output, & the vss buffer square waves on c11 & c13 look ok to me. The scan tool sees vehicle speed & the trans shifts ok. The speedo output on c15 is not there. I am at a loss as to why there is no vssb speedo output. Anybody have an answer ? Tried 2 vssb's - no help, but both work on my 94 s10 w/7427 ecm.

Try C14. Some vehicles use C14 on the VSSB for speedo and some use C15, I think it has to do with higher voltage on the C14 but same 2000ppm signal.

C14 has no output. C10 does have a square wave that is not being used. That will work for the speedo I am using. Is the C14,15 signal 2000 pulses per mile ?

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Originally Posted by bar0403

C14 has no output. C10 does have a square wave that is not being used. That will work for the speedo I am using. Is the C14,15 signal 2000 pulses per mile ?

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Yes, C14/15 are both 2000 pulse per mile.