72 Cutlass Supreme - 350 4bbl - TH350

Did not come with courtesy lights, so I bought the American Autowire courtesy light harness, connected it and started to route it behind the dash.

So, like a complete idiot I forgot to disconnect the battery (first time I've ever forgot to do that) and of course, while snaking it over the steering column, one of the hot leads (lamp connector probably) arced against something and blew the 'Clock, Ltr, Courtesy' 25 amp fuse.

Figured I’d better check and see if anything else happened, so I disconnected the battery, removed the courtesy harness, replaced the 25 amp fuse, reconnected the battery, and sure enough now nothing happens when I turn the key to the crank position.

Thought maybe either the Ignition or Neutral switch was the culprit, so like Joe P. suggested here, I unhooked the 2 purple wire connector to the NSS and ran a hot wire directly from the battery to test those connector leads.

As Joe said, one of the purple leads (lead from the ign switch) did nothing, so I touched it to the other purple lead (lead to the solenoid) and it caused the solenoid to click once, then nothing after that.

If I remove the jumper and re-test it right away, nothing happens, however if I disconnect everything, wait a while, and hook the jumper up again and test, it does the same thing, clicks once, then nothing.

Figured I’d replace the Starter/Solenoid since I had a new one already, same thing happens.

Then replaced the Ignition and Neutral switches to no avail, same thing happens.

All other key switch positions work correctly.
All dash items work correctly: lights, gauges, turns, radio, wipers, fan, etc.
Back up lights work correctly.

What have I done? Where should I go from here?

 

Sounds like a connection that goes open with high current flow. I had that happen with a loose battery clamp and also with battery clamps that had corrosion buildup between the clamp and battery post.

 

Like Kenneth stated clean your battery cables and terminals, they do occasionally get a thin layer of corrosion built up on them preventing the starter to engage. Do your headlights work? Also check your battery voltage, it needs to be around 12.7v, the .7 is very important.

 

Headlights do work.
Battery voltage is 12.4-ish. Too low?
Searching this site further, it looks like I may have a ‘resistive circuit’?
Have new battery cables coming, and will probably get a new battery as well.

Fun times indeed.

 

12.4 should still start the car, however I'd charge it.. Did you clean the cable ends and battery terminals? Don't start throwing parts at it yet. Since the headlights work, its not the fusable link.

 

I was reading through your problem description again and noticed this:It sounds as if there is a loss of power during a high current demand (engaging the starter) that recovers after time. That may be due to a bad battery instead of a poor connection I mentioned above. Can you measure the battery voltage at the battery terminals (not the cable ends) when engaging the starter? If it drops significantly, the battery is suspect. If it stays up, that points to a poor connection somewhere in the circuit.

 

A new battery, new (correct for car) cables, heat shield tubes, and the like were on my to-do list anyway, so might as well do them now. I assume a little dielectric grease on all the new connections would be advisable as well?

 

No the connections should be clean and dry. Again, why are you spending money when your problem started with you blowing a fuse while toying under the dash? Charge the battery and do a load test.

 

Ok, understood. Clean everything up and test before spending money. Thx.

 

Nothing wrong with spiffing things up under the hood but it is best to find and resolve the problem before you put the new parts on. Since your problems began after the arcing incident it sounds like you may have overtaxed a weak connection somewhere in your electrical system. Make sure you have good grounds between the battery and the engine block as well as the engine to firewall, Loose or weak grounds are just as bad as weak positive leads.

 

10-4. Thank you. Should be able to get to this today. Will post results.

 

Ok, cured one problem by cleaning up all contact points and charging the battery. Now it will crank if I jumper the purple wires going to the NSS. Thanks for all the help there.

However, the original problem remains: it does nothing when turned to the crank position with the purple wires hooked back up to the NSS.

Guess I'll start testing the purple wires backwards from the NSS: continuity, voltage, etc.?

 

If you have to jumper the NSS, there is a small possibility the switch is bad, the wiring and all else is good. However I'd be willing to bet you knocked out of adjustment. Connect an ohmmeter to the purple wire contacts (remove on of the purple wires, and see if you get continuity across the switch in any of the forward gears, reverse, or neutral. Adjust or replace the switch as needed.