GVR-4 Intermittent no start, I'm stumped

[NHerron]

Have you wiggled the battery cables. Please tell me you have the utmost confidence in your battery connection. I do not care how new the battery is.

 

[Nate355RS]

I have, and checked the voltage at the posts and connectors, they have a solid connection to the battery.

I was checking voltage at the ignition switch to double check there and I noticed visible spark coming from inside the plastic piece at the back of the ignition switch. Is that normal?

 

[NHerron]

With someone holding key in start position:

Can you check voltage between the +12V post on starter and the +12V on POST of battery (not clamp around post)

Then check voltage between neg post on battery and the starter case

It shouldn't read ANY voltage on either test unless engine is actually cranking, in which case shouldn't be over .5V on either cable.


It's just very similar to what a loose battery cable can do. All lights will work, voltage will indicate good, UNTIL you go to crank and that's when problems show up

 

[Nate355RS]

When I did that I was getting between 2v and .1v between the + starter post and the + battery post. The voltage would change everytime we tried to start it. The ground test was between 0v and .1v. Does that mean the grounds are good and something is causing electrical resistance in the circuit?

I saw the ignition switch arcing yesterday so I took it apart and found some char marks... and some cut/spliced wires.

http://imgur.com/MPjkfCT
http://imgur.com/iU2NXlB
http://imgur.com/zGAJG1I
http://imgur.com/cQLpcws

One of the copper contacts was burnt pretty bad. That might be part of the problem. I'll probably be getting a new switch today.

 

[NHerron]

Positive cable not good. .1V is okay, however 2V is not... that means the connection between battery post and terminal is dropping 2V, loose connection. I say loose because corrosion in the cable wouldn't cause intermittent. But I'm not so sure, maybe you accidentally touched ground for a split second and the meter was on it's way to 12V.

I bet you'll have luck with changing the ignition switch

 

[Nate355RS]

That's probably true about grounding the lead, it was hard to see what's what down there. The switch wasn't in stock at Advance so I ordered one, but in the meantime I cleaned the connections and reinstalled the old switch. It's working so far, so I think I might have found the problem. Thank you all for your help, this was a headache to say the least.