Isolating the starting circuit

[Doug Krebs]

So my blazer has issues with starting/running at completely random times. I'd like to make the start/run seperate from accesories, etc... I've got the the the electrical diagrams at home, but I'm sure fred, flem, john cox, etc... might have some input.

Obviously one switch would have all the accesories. The other I'm guessing would turn on the computer, associated relays, and make the starter trigger hot. I'm assuming there are more or I'm already wrong.

I'll probably look at this more over spring break.

I figured out the problem lies somewhere by the fusible link. I pulled the blazer onto the lawn to wash it off a couple days ago. Last night I was pulling it off the lawn and back onto the driveway. I must have had to jump the solenoid 15 times. It died 2-3 times in the street and an old woman almost ran into it.

[robertf03]

What do you mean jump the solenoid? Is this how you get it to fire up when the truck dies? I don't think I completely understand whats going on. When it dies, does it act like the battery is unhooked, or does some stuff still work? If nothing works, and you are jumping the starter solenoid how wouldn't the ignition and fuel injection still not be getting the 12v it needs to operate?

[agjohn02]

jumping across the terminals on the solenoid with a screwdriver/wrench to get it to engage.


put the solenoid on a relay across those two poles, switched with the ignition switch. see if that stops the problems. ill have to think about the run circuit some more.

[Doug Krebs]

Ok, I'll explain the on going problem thats been happening for a few years. The engine shuts off randomly for no reason. At first I thought it had something to do with the ignition switch, so I ghetto wired it as many of you have seen. Right now it has a toggle switch and a push button. This didn't help or solve the problem, so I kind of just dealt with it. For some reason time always solved the problem. It usually lasted between 5-15 minutes. I suspected something was heating up and the time let it cool.

Also, no gauges worked or anything dash related worked. The cigarette lighter still worked though.

This has happened twice on trails now. Thankfully they we're all on the way out or acutally on the road. Fred has gotten the privledge of pulling my dead vehicle both times:flipoff2:

I'm almost certain it's by the fusible link on the firewall, although I think it's a corroded wire and not the link itself.

I also think the solenoid died on sunday. So jumping the solenoid isn't related to this problem. At least I don't think so.

Mind you I use a ford solenoid on the fender to keep it out of the water.

Edit: Even if the I could fix the fusible link situation, I still would like to seperate the duties for KISS purposes.

[Doug Krebs]

Here's a crappy diagram...
(http://www.autozone.com/images/cds/gif/large/0900823d801156ca.gif)

[robertf03]

Theres a bunch of diagrams in Evan's on the 3rd floor.

The efi harness is about as seperated from the main harness as possible.

Have you gone probing when it dies to narrow it down to the junction on the firewall?

[DRAGOONRANCH]

painless or 12vguy. :flipoff2:

[Doug Krebs]

Theres a bunch of diagrams in Evan's on the 3rd floor.

The efi harness is about as seperated from the main harness as possible.

Have you gone probing when it dies to narrow it down to the junction on the firewall?

The efi harness is seperated, but not the couple of ignition wires.

I think I'm going to try and find a new fuse block, lights, and interior harness. Mine is pretty nasty due to nig.

[Sharpe]

A new harness is due for pigpen too. After the battery grounding incident my starting circuit is fawked, I have a jumper wire to my solenoid right now.