Unless the tach indicates it needs a trigger unit, the "trigger" wire is connected to the negative lead of the coil. I don't think it will hurt the tach even if it is a trigger unit type -- it just won't read right. IIRC the needle will bounce around a lot if it's the trigger type connected straight to the coil. The trigger unit basically filters the signal to keep the needle from bouncing -- the trigger unit connects to the negative lead on the coil. A bad non-trigger unit may have a bouncing needle too. If you need a trigger unit, I have no idea where you'd get such a thing. Sun may still have them, but you'd be better off getting a new tach. On January 17, 2006 mail@xxxxxxxxxxxx wrote: > http://www.musclecartachs.com/docs/referencesun.htm Is a web site that > seems to deal with these tachs. At a quick glance at this it looks like > this might have some answers for you. > > Good luck, > ______________________________________________________________ > Ralph Ausmann - Hillsboro, OR - > <ralph.ausmann@xxxxxxxxx> > http://mysite.verizon.net/res79g4m/ ... and "check the links" > > > ----- Original Message ----- > From: "Jerry Phillips" <jnpvegas@xxxxxxxxxxxxx> > To: <mail@xxxxxxxxxxxx> > Sent: Monday, January 16, 2006 10:54 PM > Subject: How to Hook Up a Sun Tach > > > > > I have an old Sun tach from the late '60s. It is a model SST-802, which I > think is the one that does not require an external sending unit. I do not > have any installation intructions or the harness. > > > > The two terminals are marked "Ign. Sw" which seems to be self explanatory, > and 'Trigger.' Where should I connect this? One of the coil leads? > > Thanks in advance, > > Jerry Phillips > > Las Vegas > > > > 68 AMX 390 > > 57 Chevy 283 ============================================================= Posted by wixList Archiver -- http://www.amxfiles.com/wixlist