Fresh perspective please.

[edpdx]

If by key on you mean in the 'start' position then you should have 12V on the purple/white stripe wire. Vmeter reads 10.46

If by key on you mean in the 'run' position then you should NOT have 12V on the purple/white stripe wire. Vmeter reads 0.36 It read 0.06 in the OFF position.

What happens when you apply 12V to the starter relay terminal that has the purple/white stripe wire? If the relay, the black ground wire and the associated 24V wiring are all good then the starter will engage. Applied 12v from the fuse block to the terminal with the Purple w/white wire ATTACHED. No start.

If applying 12V to the starter relay terminal that has the purple/white stripe wire does nothing then run a new known good ground to the terminal that has the black wire and reapply 12V to starter relay terminal that has the purple/white stripe wire. Added a good ground to the Black ground terminal on the starter Relay- Applied 12v from the fuse block to the terminal with the Purple w/white wire ATTACHED. No start.

If you do this and the starter engages then try the key while leaving your new ground wire in place. If no go then trace the purple/white stripe wire. It should only get voltage when the key is in the 'start' position.

Perhaps your ignition switch is bad.

I don't know if they can be tested. I'll put a new one in tomorrow.

 

[mistaken1]

You should get full battery 1 voltage at the purple/w stripe. What is the battery 1 voltage right now?

If you applied 12V to the purple/w stripe wire and have a good ground you should here the relay energize and since you have 24V on the red wire if the relay energizes you should have 24V on the purple wire.

Your relay sounds like it is bad if a full 12V did not actuate it.

Relay coils are designed to operate at a certain voltage. When the coil is energized at a the correct voltage there is a rush of current as the magnetic field builds. Once the field is built it limits the current flow through the coil. The when you remove the voltage there is rush of reverse current as the magnetic field collapses. There is also a drop out voltage where the coil will 'drop out' if the coil voltage decrease below this value.

If you have been sending 10.46V to a new, good coil you are not going to get the full magnetic field which can either prevent the power contacts from closing or not pull them in firmly causing arcing on the power contacts which destroys the relay's ability to switch the high power side.

If you have poor connections leading from the 13.2V battery 1 voltage to the purple/w stripe wire on the relay coil then that 10.46V many not be high enough to pull in the relay or it may pull it in but not hold the contacts tight leading to relay damage.

What relay are you using (manufacturer and model number), perhaps we can find the spec's on it to see what the coil pull in and drop out voltages are.

Your batteries are both fully charged right? You cannot troubleshoot electrical issues with batteries that are not fully charged.

This site has a nice description of a relay.

Relays

 

[edpdx]

I GOT IT STARTED! after scanning the TMs for glow plug ideas. I decided it was time to pull the card and clean the terminals and connection points. I also pulled the wink wire from the IP. I followed the test procedures: Pull the Pink IP wire, Pull the card and follow the protocol for testing the module. I did not understand if I was supposed to test with the card pulled or replaced. After writing down my findings, I replaced the card and p[ink wire to the IP. Turned the key to see if I made any headway. Fires right up and the voltage meter is well into the green.

It was getting late and I thought that if things continue the way they have been, that I will start it 2-3 more time then get just a click. Sooooo, I stopped while I was ahead. I could not take the suspense, so i ran out and tried it again just now. so far so good.

Thanks to all who are following and contributing their take on this matter. I will follow up in the next few days to track this if I indeed have licked the problem.

I ordered a new GP card from antennaclimber- not knowing if my card was good or bad- it is marked as 6/86 so even if it is still good; 25 years in service? might be a good idea to have a spare in the garage.

 

[edpdx]

So I have started my Blazer another 6 or so times, then click. I was unhappy; but I know I alone have to fix it, so no crying.

I tapped the relay- still hanging from the dash. Turn the key- starts right up another 6 times so far. What the heck?

 

[mistaken1]

If you are tapping your under-dash starter relay to get it to work then it sounds like that is the problem.

What voltage do you get on the coil when it starts versus the voltage showing when it does not start? Perhaps there is still an issue with insufficient voltage at the relay coil to pull in the contacts until you tap it and help it along.

 

[WARWAG]

So I have started my Blazer another 6 or so times, then click. I was unhappy; but I know I alone have to fix it, so no crying.

I tapped the relay- still hanging from the dash. Turn the key- starts right up another 6 times so far. What the heck?

Sounds like a defective relay to me.

 

[edpdx]

That's what I was thinking, the relay is getting stuck. I remember reading about the relay terminals slamming back under big loads and how some members were promoting the idea of soldering in a diode to absorb the kickback. I have some left over from when my horn diode blew, so I got nothing to lose by adding it in. I'll be out at the Blazer if you need me.