Why will my truck crank in reverse only?

Also the digital odometer says no bus.

Did you install the ecu and what year is the engine? Did you put the trans also ?

I think it is out of a 98 and I did not touch the ecu and no I did not do anything with tranny.

Transmission safety switch..?

The neutral safety switch is also the reverse light switch..it has 3 pins and usually cant be snapped in backwards..but if you didnt touch the transmission it wouldnt matter....the no bus means no communication with the ecu....did you just pull the engine and leave the trans sitting there?

Is the engine the same size as the old one

Yeah the transmission sat there on a jack. I did slide the tranny foward about 6 inches after finding out the tranny mount was broke so maybe that caused the problem? Aslo when in park reverse lights are on but in reverse the lights are off. Shifting linkage maybe?

And yes the engine is the same size.

sounds like neutral safety/reverse switch is somehow backwards.

I disconnected the shifting linkage and found out the rod is bent. So I the truck was not going in to park. I was able to put it in park by hand. If my instrument cluster goes bad will that prevent my truck from starting? I tried unplugging the ecu to see if it would still throw the check engine light and the no bus and everything remained the same. The check engine light came on and the no bus.

When I finished with the engine swap my battery was dead. I tried to jump it with my trail blazer and even then still did not sound right, So I used a battery charger that was pretty strong and while it was charging my son said he smelled something that smelled like a cap gun that was just shot. I did smell it to. It was from the drivers side. But when I was jumping it with my trail blazer it seemed like it was not getting any fuel to the engine. It is a new fuel pump and sending unit in there.

Could it be Ignition control module?

I heard that when you change your motor you have to have the computer flashed. Any truth in that?

Crankshaft position sensor wire was pinched between bell housing and engine block which caused a short. I unplugged the crankshaft sensor and the no bus went away and all gauges are working. So in my case pay attention to the wires when installing a engine or anything else for that matter. Thanks for the feed back on here very much appreciated.

Did u figure this out ? I have a 2002 spectra. I replaced tranny with another used one. It was doing almost same thing but worked a little better. I then replaced the tranny brain and the prndl on the tranny. Now it only starts if I turn it over then shift into reverse. What's the deal???? Did I get sold a bad tranny or is something else wrong?

Did u figure this out ? I have a 2002 spectra. I replaced tranny with another used one. It was doing almost same thing but worked a little better. I then replaced the tranny brain and the prndl on the tranny. Now it only starts if I turn it over then shift into reverse. What's the deal???? Did I get sold a bad tranny or is something else wrong? raynewells@aol.com