Fusible link on the load side.

Yes, that is correct, which is confusing.

The red wire goes through the multi-pin block connector first, so by jumpering it I have by-passed it, of course there are other wires that also my require jumpering.

Thanks for the tip on checking the output of the yellow wire while jumpering.

I still have to check the grounds and all the fusible links under load. I now have the schematic, which may help fault find.

I guess it still might be the new neutral safety switch is at fault, doesn't explain the 0v on the supply to the ignition switch, but maybe I have more than one fault going on here.

 

Sounds like you have more than one problem. First it sounds like always hot fusible link/red wire to the ignition switch is not always hot. Since you have 12v to the terminal block the fusible link must have blown with all the ignition switch/rewiring work. Second since providing temporary voltage to the ignition switch doesn't fix the problem then you have to check the operation of the new switch. It may be faulty out of the box or you may not have aligned the gear teeth correctly. Again that check is to see if 12v appears on the yellow output wire with the switch on start with temporary 12v to the switch. If you have output at the yellow wire then it's time to check the next thing down the line which would be the purple wire at the output of the crank fuse on the way to the neutral safety switch. If there is no output at the switch then there is still a switch problem. Either way the power to the switch needs to be corrected by either replacing the fusible link or by running a new fuse protected red wire from the terminal block to the switch.

 

After digging around I found that the 12v feed to the ignition switched has been spliced together in the past, and was not good, re-made it and soldered it - it has fixed the 'no 12v' at the ignition switch issue, so that is one mystery solved.

I have a switched 12v (when trying to start car) on the yellow wire after the ignition switch, but 0v on the yellow wire on the starter relay.

So, its pointing to either the wiring to the starter relay or the new safety neutral switch. I'm fairly confident that the neutral safety switch was installed correctly, it comes with a clip to keep the position locked when you are installing it, and I aligned it, it can only go on a certain way. I have to say though, the connectors were a PITA to get off, so maybe the wiring or connectors there are bad.

I made a simple diagram to help me.

 

You need to keep moving methodically through the circuit path. Your diagram is incomplete, pls refer to my most recent circuit flow. Now that you have good power to the ignition switch and 12v output from the switch during start let's move on to the next component. That yellow output wire from the ignition switch goes first through the d1 connector and then continues as a yellow wire to the crank fuse. The output from the crank fuse is a purple wire on its way to the neutral switch. When cranking, what is the voltage at the output of the crank fuse/purple wire?

 

I'll check that, what I have found is if I jumper 12v to the where the switched 12v (yellow wire) goes into the starter relay the car starts and runs fine.

So the yellow wire that goes into the relay is either faulty, or further back from there.

My friend came over and suggested a troubleshooting tip, I manually released the shift safety interlock, so I could than run the shift lever up and down, while I was running the shift lever up and down he held the ignition key in the start position, as soon as the shifter hit reverse the car briefly attempted to start, so he said it is highly likely that you need to adjust your safety neutral switch, increase the tension on the linkage.

I think this may have been suggested earlier, but with the 0v on the red ignition wire throwing me off, and the new starter relay being fried, it confused me a little.

 

Well then if you have 12v going into the neutral switch during start then it's the neutral switch. If you don't then it's the crank fuse. On any of these it can be the associated wiring since we now know that the truck wiring has been hacked poorly at least once before. Your almost there.

 

Ok, I think I've got this.

With the new neutral safety switch installed, what I have now discovered is this.

I move the shifter to the park position, I then went under the car and gave the lever which attaches to the transmission a good push, and it goes when more click forward, so this is true park, and the car starts, move the shift lever to drive and then back to park and it's out by one stop again.

The switch is aligned correctly, the shaft and switch are shaped so as you can only put on one way around, I have tried every using adjust on the switch mounting bracket (2 bolts) but it is to far out for it to compensate. I then attempted adjusting at the cable, underneath the car, there is white clip on the shift lever cable which you pry apart slightly, you can then adjust the tension, I have tried every adjust I can think of, increased tension, backed-off tension, what ever I do the cable does not have enough rigidity to give the shifter the nudge to the last stop (park), which is also the furthest distance it needs to travel.

So, I'm assuming the cable is worn out, and I have no reason to believe it might be the original one, so 20 years old. How easy is it to replace? Maybe I should start a new thread?

 

Sounds like you have the electrical part under control. Here is proceedure for adjustment of the switch and linkage. If this does not help, I would start a new thread.

George

 

Ok, finally got this fixed, it was the shift cable, once it was removed you can see where it has worn and failed, the outer sheath was worn away and the inner sheath and cable and creased up, so got a new one and all is working great!

One lingering issue is the rear brake lights don't work, but unusually the high level brake light does. Rear taillights work, reverse etc.

Got the rear brake lights sort fixed for now, if I jam a piece of cardboard and press down on the hazard light switch the brake lights then work, so need to replace the hazard light switch.

Thank you for you help George, much appreciated.

 

My pleasure.

The high center brake light circuit does not pass through the hazard assembly like the lower rear brake lights do.

George