Starter with no power

[jheiderscheit48]

I recently got a 78 k-10 and it had no mechanical issues or electrical issues interfering with it running. After about a month it would not start consistently then eventually it would not start. It basically acts like you are trying to start it in drive or reverse. The gauges move when you turn the key but the small wire on the solenoid gets no power at all. It is a new starter because the old one died on me and this starter has started the truck once or twice before it got no power. There is a new neutral safety switch in it and starter module relay and it is fully activating when the key turns, yet the solenoid is getting no power and I'm clueless on what to do.

Sent from my VS985 4G using Tapatalk

[gunrac]

i had an issue w/a 76' yrs. ago. Cab mounts were shot, making the rear of the cab sag, putting a bind on my shifter linkage not letting it go all the way into park. Might try popping off linkage, manually pop shifter on tranny up into park. It could be that simple.

[Irish_Alley]

can you try to start it in neutral? when you say it acts like youre trying to start it in rev or in gear do you mean that the key wont turn very far

[jheiderscheit48]

Like the key turns all the way yet nothing happens. You can turn the key one click and the gagues come on for battery and temp, then when you turn the key all the way the temp gauge turns all the way to red line with nothing else happening

Sent from my VS985 4G using Tapatalk

[bd]

Is power reaching the neutral safety switch during crank?  What were you referring to when you posted, "starter module relay...is fully activating when the key turns?"

[jheiderscheit48]

My bad, I meant to say ignition switch, always call that the wrong name, and not 100 percent sure How to test if  neutral safety switch has power, I have a test light and multimeter, but I don't have a lot of experience in using them because I'm 17 and this is my first fixer upper truck.

Sent from my VS985 4G using Tapatalk

[bd]

Five wires should connect to the neutral safety switch: two green, a dark blue, a white with purple stripe, and a solid purple.  Ignore the green and blue wires.  The white/purple is the "crank" wire from the ignition switch.  Solid purple connects to the starter solenoid. 

Set the e-brake and make sure the gear selector is in Park or Neutral.  Clip your test light to a bare metal ground and switch the ignition ON, but do not crank.  Probe a couple of fuses to prove that the test light is properly grounded and actually illuminates; relocate the ground clip if the test light doesn't illuminate.

Probe the white/purple wire at the neutral safety switch and turn the key to Start.  The test light should illuminate each time you attempt to crank.  If the test light does not illuminate, probe the white/purple wire where it connects to the ignition switch and turn the key to crank.  If white/purple remains dead, verify that both red wires feeding the ignition switch are constant battery voltage.  If both red wires are hot, but white/purple never energizes, either the ignition switch is out of adjustment, or it is faulty, or the wires are not making good connections with the switch.

If the white/purple wire at the neutral safety switch energizes with the key, probe the solid purple wire and retest.  If purple remains dead, the neutral safety is out of adjustment, or faulty, or the wires are not properly connected to the switch.  If the purple wire energizes, but the starter doesn't crank, recheck the purple wire at the starter solenoid - make sure it is connected to the "S" terminal.  If purple remains dead at the solenoid while attempting to crank, there is an open in the purple wire between the neutral safety switch and the solenoid.  Simply follow the wire to locate and repair the open.  If the purple wire energizes at the solenoid, but doesn't crank the starter, recheck the starter.

[jheiderscheit48]

The white/purple wire energized but the solid purple did not, so how would you go about adjusting that?

Sent from my VS985 4G using Tapatalk

[jheiderscheit48]

And I do not have a dark blue wire if that makes any difference

Sent from my VS985 4G using Tapatalk

[bd]

A missing blue wire is not significant.  Set the e-brake and shift the gear selector into neutral.  Loosen (do not remove) the two neutral safety switch retaining screws and rotate the switch back and forth around the column until the engine cranks.  The switch won't rotate in either direction very far before reaching its adjustment limits.  Tighten down the retaining screws and then verify that the backup lights illuminate ONLY in reverse and the engine cranks ONLY in park and neutral.  If the purple wire never energizes, replace the switch.

New switches generally have an internal shear pin that locks the switch in the neutral position during installation.  When installing a new switch, shift the gear selector to neutral, install the switch and tighten it down.  When the gear selector is rotated out of neutral, the shear pin will snap and the switch will be properly adjusted.

[jheiderscheit48]

The engine will not crank at all, I even took off the neutral safety switch and tried sliding it by hand, and the solid purple wire get its power from the white/purple wire through the switch correct?

Sent from my VS985 4G using Tapatalk

[bd]

White/purple changes to purple through the neutral switch.  Set the e-brake, shift into park and momentarily jump wht/ppl to ppl to see if it will crank.  If it cranks, make sure the wires are properly connected to the switch.  If they are, replace the switch.  Whatever you do, DO NOT leave the neutral safety switch bypassed!

[jheiderscheit48]

I pulled both wires from the plug connector and had them pressed together and tried to crank and nothing, does this mean I need to hunt for a broken wire somewhere?

Sent from my VS985 4G using Tapatalk

[bd]

Well, if you supply power to the purple wire (Ckt 6) at the neutral safety switch and it never reaches the starter solenoid, then you need to start tracing the purple from the switch all the way out to the starter.  Start by checking for power on Ckt 6 where it exits the bulkhead connector.  That should narrow it down to which side of the firewall has the problem.  Look at the 1978 Wiring Manual for an illustration of which cavity is occupied by the purple solenoid wire.

Edit:  established hyperlink

[jheiderscheit48]

I'm trying to access the link to the manual and I believe the link is broken

Sent from my VS985 4G using Tapatalk