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rfmaster · 05-01-2008, 07:57 PM

Cav

If you are going to get external VSS to work with conventional mechanical speedometer make sure that you know how many pulses your ECM or PCM is expecting. Older C3 ECM which were used with TBI expect VSS to produce 2000 square pulses per mile. You probably know this but later PCM expects VSS signal input to function properly. According to JTR a 40 pulse per driveshaft revolution speed sensor was used on 1993 and newer trucks with automatic transmission, 1994 and newer rear drive cars with the automatic transmission. An external VSS is a lot cheaper than new digital dash.

That should be a sweet running truck when it is all done.

//RF

05-01-2008, 07:57 PM	#21
rfmaster Registered User Join Date: Oct 2003 Location: OC CA Posts: 1,374	Re: transmission swap Cav If you are going to get external VSS to work with conventional mechanical speedometer make sure that you know how many pulses your ECM or PCM is expecting. Older C3 ECM which were used with TBI expect VSS to produce 2000 square pulses per mile. You probably know this but later PCM expects VSS signal input to function properly. According to JTR a 40 pulse per driveshaft revolution speed sensor was used on 1993 and newer trucks with automatic transmission, 1994 and newer rear drive cars with the automatic transmission. An external VSS is a lot cheaper than new digital dash. That should be a sweet running truck when it is all done. //RF __________________ "The Beast" 1975 Chevrolet C20 longbed 350/700R4! with 3inch body lift Dual Flowmasters Super 40's! TBI retrofit completed (2007-07-29) New 383CID (+030) 08-304-8 9.5:1CR x36,005 (2012-12-17)