I tryin to help a buddy of mine he has a 2001 S10 Blazer with the Vortec V6. The truck has always had problems startin but now it won't do anything. Before he might have to giggle the keys a little the next day he might have to slam the door. He just did differnt tricks to get it started he has takin it to dealerships but everytimeit starts right up. Well now it won't even crank You turn the ignition and all lights come on, but when you turn the key to crank it over no sound and all the lights go out. I was thinkin it might be the ignition switch wire harness. The starter tested good at a local shop. He doesn't want to end up buying a new harness if it doesn't fix it. Question is there a way to bypass the harness to tell if this is the problem. And could there be something I might be overlookin. All fuses and relay's are good and grounds are tight.

Thanks, Brian

 

Tight , clean connections at the battery?

 

Yes, I'd have a look at the battery as well. If it is the original AC Delco battery, they are known to have corrosion issues on the inside of the battery that affects the connection of the positive post. Sometimes you can't see it until you pull the positive cable off and the attaching lug inside the battery comes off with it. If it is the original battery, then I'd say its time for a replacement anyway.

 

I've cleaned the positive side and made sure the negative side was tight and the battery is reading 11.58 volts. I just can't figure this out. I forgot earlier that when I try to turn it over all lights go out except check engine and battery light. I even tried jump startin it thinkin a bad cell in battery before I got out the voltmeter.

 

The light thing sounds EXACTLY like when my positive terminal was corroded on the inside. Is it an AC Delco battery? Do you know how old it is?

You could always take it out and have it load tested. It may read good on a DMM, but you really need to see how it reacts to a load. Put the DMM on the terminals and have someone else turn the key to start it and see what the voltage does. If it drops a bunch, you've got a bad battery.

 

I would start looking at these:

starter relay(would lean towards this due to the needing to bang things)
ignition control module
Ignition wires from colum (also this due to the needing to bang things)
Ignition wire at starter

When you volt test a battery it should show up over 12volt (avg 12.40), not saying its the cause, but saying that it could use a boost/charge. If you can find the ignition wire in the harnesunder the colum, you can tap it with the volt meter and see if it goes from 0 to 12. If it does then the signal is getting out. Then you would need to check your relays. Hold to start, feel for warming relay, tap each one. But don't hold it til you start to smell smoke no more then 20 to 30 sec per try to keep it fromsmoking a wire or two.These relays are like signal flasher fuses. They have a metal tab that conects and disconects (for engage and disengage) when power is added to them.

 

I had the battery load tested it was low on voltage but tested fine. When Itry to crank it over you can feel the starter relay clicking over. Does anyone know the color of the starter wires near the underhood relay center and maybe where the come into the box at?