no backup lights after AW4 swap - tried all listed fixes.

I have just replaced a BA10 with a AW4.
Mine is an 89 the AW4 and engine wiring harness are from a 90.
Everything is working except the backup lights.
Need to get it inspected and with my luck they will check the backup lights.

I've searched and check the items listed in other posts about backup lights not working.
The bulbs are good.
I've clean the NSS and when in reverse there is continuity between pins A & E.
The Trans fuse is good.
The Comfort/Power switch lights up when presses.

Is there any other connection or wiring that has given anyone problems with backup lights.
Or can anyone point me to another possible problem?

Do you have voltage at pins A&E with the tranny in reverse? I had this problem at one point and it was a very corroded fuse. I'd have +12 at the NSS until I put it in reverse and all the voltage was getting dropped across the fuse.

The fuse is not corroded but is has been there for over a decade and had some discoloration on the blades. I did use electrical cleaner on the fuse because I did not have a spare. (picking that up tonight)

I'll check the voltage and try a new fuse too.

I used the strap on the firewall for a ground. Engine running.

Pins A & E have .4 volts when in reverse.

Tranny gets enough volts to operate. Did I have a bad ground?

Do I have a bad connection somewhere else in the harness?

What voltage should I get on the pins?
Would it change if the key was in the ON position vs engine running?
Which pin(s) carries the power to the NSS or does it matter?
Asking so I can check volts with the connector is unplugged?

I hate electrical problem :tear: