ignition switch question:

[edpdx]

Read applicable threads already; but no help so far.

I have been chasing a "No Crank" problem for the past 48 hours. Ran wiring down as per TM. The situation is: Turn the key. All the requisite dash lights come on and cycle. All I hear is a click. Batteries checked, starter checked. Reminds me of an ignition switch I just changed on my Daughter's El Camino.

Q: If I am getting dash lights, could the ignition switch still be the problem? I pulled it; but did not know how to test it. Cleaned the contacts, but still no go. Anyone know of a way to test this component?

 

[Jtspendy]

when you say batteries check did you test voltage or amps? A battery can have a bad cell which will allow voltage to look good but you loose all your cranking amps

 

[edpdx]

I am not sure how to test amps... Is this what a "Load Test" does?

I checked voltage at the purple wire at the starter solenoid per TM -20's Malfunction test #42. I got a reading of 19.5Volts. Is this too low to crank the engine?... even a little?

 

[ralbelt]

TM 9-2320-289-34
Chapter 2
Page 1

C. When troubleshooting a electrical malfuction

1 Ensure that both batteries are fully charged.

 

[edpdx]

ralbelt, I read that already. In my OP I state that the batteries were checked- I didn't mean I checked them and they were dead. They each showed 12.55 volts. That seems like enough to crank the engine over, yet I am only getting 19.5 volts at the purple wire at the starter solenoid. I am looking in the forums now to find out if 19.5v is enough to crank the starter.

 

[mistaken1]

If each battery is 12.55V then the purple wire should have something close to 25.1V.

A bad connection (high resistance) can cause a voltage drop when current flows.

Bad batteries will do that (need to be load tested to know for sure).

I have seen others with a bad cable that links the batteries together. When a load is applied that link has a high resistance and the truck will not start. The terminals look good but the cable itself is corroded.

 

[mistaken1]

Also the purple wire energizes the starter solenoid (on the starter). 19.5V may not be enough voltage to fully actuate the solenoid.