Just replaced the Auto Trans

fleming.a.j.s, Aug 29, 7:29am
on my 1990 Bluebird 1800 with a unit from a (apparently) 1800 Primera.
Had to swap a few externals from the old to the new, but nothing major,Wiring plugs lined up, but when I try to start the Engine, I find it has no spark when turning over. Neutral start is good, but puzzled about what I may have done wrong, Can any Mechanic here with Nissan experience offer any advice please!

mechnificent, Aug 29, 8:05am
It is fairly common in a lot of makes to have neutral input to the computer to set the idle speed and things differently when they are in gear, but it doesn't kill the engine ever.
I'd kinda suspect that it is a coincidence. perhaps something you accidentaly bumped doing the work.
I'd just start diagnosing the no spark and see what i found.

franc123, Aug 29, 8:26am
You didn't leave off any earth cables that were connected to the trans! A lot of Jap cars have one or more smaller cables as well as the starter ground cable that go between the engine/trans and bodywork, or straight back to the battery. Leaving these off can cause all sorts of weird problems.

cowlover, Aug 29, 8:35am
Don't supose the inhibit switch interupts the ignition circuit as well as the starter by any chance!

fleming.a.j.s, Aug 29, 8:59am
I dont think so "cowlover", it will only turn over in Neutral or Park.
sadly I'm not so familiar with electronic ignition, though there is one live lead to the distributor and the coil when the ignition is on. I tried a spare coil that I have but made no difference

budgel, Aug 29, 11:21pm
Can you re fit the wiring from the old unit!

You could ask here: http://www.npoc.co.uk/forum/registration_rules.asp!FID=0

fleming.a.j.s, Aug 30, 5:48am
Yes budgel, thats what I have done, real puzzle !
Will report back when I get to the bottom of it.

mm12345, Aug 30, 9:05am
Just an off-chance.
Did either or both bellhousings have a crank angle sensor (usually near the top somewhere - slots in to read crank position from ring gear).
These are easily damaged - best removed when lining up trans to engine, then replaced when it's bolted up as they can be damaged by accidentally contacting the ring gear.If it had one - and it's now broken, or if there's a spare connector because the new trans didn't have the sensor, then the engine won't go, probably no spark.
For some reason, some basic (non-VVT) Nissan engines have them, and some don't.
Some of the bellhousings on car models without the sensor still seem to have the hole cut out, and threaded hole to bolt the sensors in.

petermcg, Aug 30, 9:16am
Sounds a bit like inhibiter switch is some how wired incorrectly,if its affecting the spark but not the starter