I decided it would be a good idea to install a Tachometer on my 87 Chevy bus that never came with one. From my other thread, Ive made known that I am experiencing a throttle cut off at 49 miles per hour and have tried various things to determine why this just instantly started happening. Though the redundant throttle spring on the carb DID need to be reset, I'm still experiencing the same problem. Perhaps I am hitting my top RPM earlier than before and that is whats causing some sort of governor to kick in?
In any case, here is what I bought: Before I head out to look and see if the bus was "pre-wired" to accept this factory tach, does anyone have any insight on what these wires and the one harness go to?
Tachs on gasoline engines have dials that read to 5000 rpm. The signal wire goes to the tach terminal on the distributor.
Tachs on the diesel pulses come from a sensor on the flywheel housing. They read to 4000 rpm.
The wire colors on your tach are different than in my book. Make sure you have the right tach for gas or diesel as they may be different.
Gray=IP lamps Pink = IGN 12v Black= Ground Brown= Bulkhead DK Green = Tach signal
The connector should be under the dash.
I just noticed that I have a harness under my dash board that is hanging in the area where the factory tach would go. It has three wires: two whites and one orange..
Orange with white on GM are usually to the brake lamp switch circuit. I wish there were a way I could scan the diagram I have. It's a big book and you have to jump back and forth through the pages to trace out the ends.
“The good thing about science is that it's true whether or not you believe in it.” Neil deGrasse Tyson
Orange with white on GM are usually to the brake lamp switch circuit. I wish there were a way I could scan the diagram I have. It's a big book and you have to jump back and forth through the pages to trace out the ends.
no worries. I just bought this exact book on ebay.
My 87 gm carpenter doesn't have a tach either. I'm gonna peek under the dash later and see what is there. Good find on the book BTW, they are priceless when needed.
“The good thing about science is that it's true whether or not you believe in it.” Neil deGrasse Tyson
My 87 gm carpenter doesn't have a tach either. I'm gonna peek under the dash later and see what is there. Good find on the book BTW, they are priceless when needed.
Just wanted to let everyone know I disconnected a few wires (plugs) on the passenger side fire wall and now the bus goes well over 55 mph like it used to. Not sure why.....I am still going to get this tachometer installed so reassure myself that I'm not going to high on my revs.
Installing Tachometer - GM Bus
Posted - 03/12/2012 : 11:43:34 AM
