93 chevy 6.5L diesel pickup

       Here's a good brain teaser. I have a 1993 Chevy 1 ton 4x4. It has the non-computer controlled 6.5L diesel. There is an ECM for the transmission. Also there is a tach in  the instrument cluster. I  installed my Astrostart 2106 in it yesterday and am having tach problems. The Astrostart requires you to set the number of cylinders to match up to the tach signal found. I used the white wire behind the cluster and when I test it (with a astrostart tach meter) I get a 12 cyl. setting at 800 rpm. Unfortunately that is the max. setting on my 2106. If I idle my truck down (800 rpm), it will start and run, but when the cold (high) idle solenoid is engaged (1100 rpm) the starter  starts the truck and then shuts down and the troubleshooting code is overrev protection. I cant find another good tach signal, and the the one I did find pulses too fast to properly set up the starter. I have tryied Astrostart's DTS-5 Tach generators on the alterntor in the past on previous diesels but I get inconsistant results with them. Anyone got any ideas where I can use the current tach signal I have and poosible filter it down or somehow manipulate the signal so I shows maybe half the pulses it is putting out.

You can try the LIGHT GREEN wire at the ECM behind the glovebox. Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

Also, white wire at the alternator.... Gus Wherever I go, that is where I end up......

I tried every wire at the tranny ECM and find no real tach signals, also the white wire at the alternator doesn't work. Any other suggestions?"Retired" car audio/security istaller after 12 years and carpal tunnel in both hands.