Faulty starter

[ackland3]

On my 84 k10 i keep having shorts or at least i think i am. i'll turn the key and get a click but no start (it's a brand new starter) i've found and fixed a couple shorts and then it'll start and run by the key until i drive it then i have to jump across the solenoid for it to start and sometimes it'll start with the key after doing this sometimes not. any ideas?

[Shifty]

Sounds "switch-ey" to me....are you getting a solid (at least) 12v at the starter when it fails?

[ackland3]

yep everything appears fine i've replaced the switch once already unless my short is somewhere in the mess of a wire bundle for the dash

[bd]

It doesn't "ring" of a short - more like low voltage due to a discharged or weak battery, or voltage loss from a poor connection or compromised appliance.  Have the battery properly load checked.

The starter circuit consists of the battery, starter, ignition switch, and interconnecting wiring.  Begin your diagnosis by narrowing down which part of the circuit is presenting problems starting with the battery.  Don't make any assumptions.  Make sure the cable connections to the battery, engine block and stater solenoid are clean and tight.  Check the battery cables for any signs of corrosion or swollen insulation, especially in the vicinity of the battery terminals.  Use your voltmeter to measure voltage drops while attempting to crank the engine.  Measure between the battery negative terminal post and the starter case while attempting to crank.  Measure between the battery positive post and the solenoid 3/8" B+ post while attempting to crank.  Measure between the battery positive post and the solenoid "S" terminal while attempting to crank.  Post your results.

[ackland3]

did the voltage reading and i got 12.4 on all except to the starter case i got 0

[bd]

If you measured 12.4 volt drops across the wiring, either the wiring is toast or you connected your meter incorrectly.  Did you take the measurements while cranking the engine?

[ackland3]

Sorry no I measured 12.4 both while cranking and not and got 0 volts on body of starter

[bd]

Referring to the diagram, below, where did you connect the meter leads when you measured the voltage drop between the battery positive post and the solenoid 3/8" B+ post while attempting to crank?

With the engine off connect your voltmeter between the battery's positive and negative posts.  What is the reading?

[ackland3]

I think I found it! a break in the wire from the firewall to the starter s terminal.

[Chevygold]

Hi there hope you're right, sounds as if the damaged wire was allowing some voltage through to make the solenoid click but not enough to pull it all the way in to engage the starter and make contact with the contacts inside to send 12v to spin the starter.
Graham