You made me think of another possibility George.

Is it possible to have the relay wired backwards?

The three posts on the relay have the numbers 87, 85 and 15 if I remember correctly. (It's 10 degrees and dark outside so I'm not going to look now!)

From what I could decipher from the Haynes manual, I think the wires should go from;

1. solenoid to 4th gear lockout contact;

2. 4th gear lockout contact to relay post with pigtail to pilot light;

3. 12v to another relay post;

4. one side of "on"-"off" switch to ground and the other to the third relay post.

The Haynes manual doesn't say which numbered post goes to which wire, so I guessed! What do those numbers on the relay represent anyway?
--
'86 745T, '72 144E, '70 145S, '68 122S Estate, '60 544