Hamboned.

Would you please do the quick ,Guaranteed to answer what is going on ?

Step 1. do the back up,lamps come on with the key on and lever shifted to reverse ? If they do, then no sense playing around because we just proved power is getting to the trans sw...They either come on or they don't, which is it ?

Step2 run that jumper wire from the relay terminal 86 touching the battery positive post. You are right there and you can hear the starter relay work when you do that
Do you hear the start relay work, ?
If yes and the starter solenoid still doesn't engage the starter , we have by passed everything up to and including the start relay.
Since you were able to get the starter solenoid to operate bringing power to the wire coming off terminal 87 , we know that part works.
Up to this point we know the start relay itself is OK and works and we know the output wire from 87 works, all you need to do now is find out why power is not getting sent through from terminal 30 on the starter relay to 87when the relay is energized. This is all very basic stuff and for the life of me cannot understand why these simple things were not performed..

 

While doing the bench test again, just do a resistance check on the relay as well.
1) energize the relay: 85 to ground, 86 to 12v
2) 30 to ohmmeter red, 87 to ohmmeter black
how many ohm you get (50-150)?

So basically when the relay energizes there should be continuity between 30 and 87, doesn't matter if there is a 12v feed to terminal 30, it can be a ground feed as well.

Yes this is basic stuff but not everyone has the experience and knowledge to troubleshoot the problem, and then not everyone has the right tool/equipment to perform the test correctly. This thread has already reached 92 posts, there is no reason for 3 of us to give up at this point.
Worst case I would just bypass the starter relay by running a wire (same or heavy gauge than what's currently attached to the S terminal of the starter solenoid) from pin 12 of the range sensor directly to the S terminal, then remove the starter relay and call it done. Don't even need to add any inline 40A fuse since this new circuit is protected by the Fuse 3, the BN/PK wire.



S terminal shown above.

 

Ok I did bench test on relay itself and it does click and getting a resistance of 73 ohms , and reverse lamps for come on with key on and shift in reverse, when I put jumper wire to 86 from positive post it does click and stater turns over

 

Yes Reverse lamps do come on

 

Did you try putting power to the starter relay terminal 86 to get the starter relay to operate? Let us know if it operates or not.

You have narrowed down the problem to be between the starter relay and the starter solenoid on the starter.

 

Yes when I put power to relay 86 by itself and it clicks and when I put relay back in with power to 86 terminal it turns over starter

 

You didn't mention a jumper wire from battery 12v post to terminal 30, just jumped from battery 12v post to terminal 86 from underneath, that means the TN/RD wire coming from pin 12 of range sensor is not making good contact to your terminal 86. You tested from the bottom it works, you tested from the top (really means the relay is plugged in), it didn't work.

Without the relay socket extension it's just more difficult to isolate the issue.

1) Remove the relay, voltmeter red to terminal 86 from the top of relay box, voltmeter black to chassis ground, turn the key to START, any voltage?
2) Plug the relay back in, voltmeter red to terminal 86 from the bottom of relay box, voltmeter black to chassis ground, turn the key to START, any voltage?
3) Plug the relay back in, jumper wire from pin 12 of range sensor to terminal 86 from the bottom of the relay, make sure it's the SAME SPOT (that you got it to work from battery 12v to terminal 86), turn the key to START. This is to assume your TN/RD wire is not making good contact to terminal 86 from top to bottom and from bottom to top.

 

No start when i turn key to start with jump wire from pin 12 on range sensor to terminal 86 on bottom or top

 

0.18V really means you are not getting any voltage from the TN/RD wire, you will need to find out why that wire is almost broken at terminal 86. You tested this wire so many times previously and you got pretty good voltage and this is the first time you are getting next to zero volt.
Since you jumped directly to 86 (from underneath) and it works, jumped directly to 87 (from the top) with relay removed and it works, every other terminal 85 (ground) and terminal 30 (12v feed) are good too as well as the fuse 3 and 34.

1) You should also test the resistance and continuity from the top of 86 to the bottom, test at multiple spots on the bottom and see where the break is, 5 ohm or less is good, find out which spot gives you higher resistance and start from there. Additionally, test resistance from pin 12 of range sensor to bottom of 86 and top of 86.
2) Without removing the range sensor, carefully insert a jumper pin into Pin 10 (BN/PK), then connect this to the voltmeter red, voltmeter black to chassis ground, you should get voltage at pin 10 when key in START. Just like how you tested the pin 12 previously but pin 10 this time. Pin 12 is the output, 10 is the input.

 

What if Hamboned was right when he suspected the ign sw back in August ?