Re: Ignition switch failures.
 

After my adventures I would recommend adding crmpers, female spade connectors, some Super 33, and a good sharp knife (to carve away the melted plastic connector) to your glove box supplies.

Re: Ignition switch failures.
 

I don't recall where I saw it, but IIRC the "Start" circuit can draw up to 70A. A relay should be sixed for that current, if I am correct.

Re: Ignition switch failures.
 

I found my stock system pegged at maximum amps for the alternator when running all the stock accessories.

A local electrical shop confirmed my suspicions by doing the same current draw check on the wiring harness. He snickered in a comment to me, " Why did GM do that?"

I am thinking the AC relay circuit would also solve some of the problems as it takes the high fan current load away from the dash harness I believe.

Re: Ignition switch failures.
 

GM didn't have a monopoly on that kind of electrical engineering. :lol:
With my 70 Javelin if it is driven daily, in traffic, during the winter, with the heater, lights, using the brakes frequently, with the wipers on, the battery will be too drained to start the engine in 4 to 5 days unless I take it for a 10 mile run on the freeway at least once.
The factory 35 amp Motorola alternator doesn't charge at idle and they really are optimistically rated. After testing several alternators and regulators I never saw one that made more than 30 amps.
When these vehicles were designed stop and go, bumper to bumper traffic wasn't a problem to consider. They only work with enough run time on the highway.

Most definitely adding the A/C circuit can reduce the dash harness load since you can pick where the blower power is being supplied from.

Re: Ignition switch failures.
 

My wife has a '14 Kia Soul that the system draws about 6A for up to 1/2 hour after the vehicle is shut off. I thought something was wrong with it after it had a dead battery and I was checking the system out. I went up to the dealership to talk to them about it. We walked over to a new Soul (2016) and checked it (I had an inductive ammeter that can be placed against the wires to check for current) and it was drawing 10A! These new cars also have to be driven every few days for at least 15 minutes to keep the battery up, and rust off the brake rotors. That information we got direct from Kia, as people's cars are parked for long times due to staying at home to work, so they're getting dead batteries and squeaky brakes.

My truck can and has sat for months without these kinds of issues.

Re: Ignition switch failures.
 

Any updates on your electrical gremlins? Would be nice to hear what you have found.

Re: Ignition switch failures.
 

I'm sorry to say nothing new at the moment. Between spring time tasks around the house and having to work extra days at work my opportunities for continuing the trouble shooting have gotten pushed off to the first or second week in May.
Thank you for the reminder.

Re: Ignition switch failures.
 

Okay I got some time to dig deeper into amperage loads. I checked the fan amperage at the firewall, at the fan speed switch, and at the ignition switch. The results were that on my truck the fan amp draw is about 5 to 6 amps constant and never more than 8.5 amps on fan start up.
I looked into what a starter solenoid should draw and I found some GM documentation that said that solenoid pull in amps should be 42 to 48 amps and the maintaining circuit amp are 7 to 8 amps. My pull in amps are less than 10 and the maintaining circuit is about 4 amps. I have a later model GM gear drive starter which appears to draw less amperage to operate the solenoid.
Nowhere in the system have I found any component that is drawing amperage that is out of specification which leads me to believe the currently available starter switches are not able to survive the loads that a factory switch can.

Re: Ignition switch failures.
 

Made cheaper and cheaper, that's for sure. I had to put a new ignition switch in mine a couple years ago. Bought it at NAPA, FWIW. I bet there's guys on here in the older truck forum with the original stomp starter pedal and it's still working.

Re: Ignition switch failures.
 

I'm having the same issue with my 70 C10. It is a 350 with sniper EFI, dual electric fans and HEI distributor. Wiring is all new (American Autowire) and done by a professional shop.
First time we started it to program the EFI started fine and shut off fine. The second time we started it, guess what it still ran with the key off- unplugging the fuel pump shut it off. During this test run the electric fans would not come on (Derale).
Here is what I have checked and fixed so far:
1. The red wire going into the fan relay was not crimped very good and had worked its way loose. Corrected this and it still was blowing the 30 amp inline fuse. Replaced 25 amp relay and it no longer blew the inline fuse. However the fan control module adjustment does nothing- even at the lowest setting fans do not come on. I'm thinking the control module is shot.
2.The white wire going to the HEI has power when the ignition switch is on and does not when it is turned off.
3. The control module is wired as per directions: red wires to the battery. Module harness: negative wires to the 30 amp fuse/yellow wire to ignition/black wire to battery negative post and green wire to override.
4. I have tried two different and the same results will not shut off when the key is turned off.
5. The only other thing I discovered is that the 30 amp inline fuse on the control module for the fans was blow again. It wasn't when I started it. So it either had to happen when I was trying to adjust the fans or turning the switch off.
6. Installed a 40 amp relay today and the 30 amp fuse is still blowing either when I try to adjust the fans coming on or when trying to shut off the engine (which still runs). In checking the wiring harness on the module- in the 30 amp fuse, the terminal with the negative wires coming from the fan light up a test light whether the ignition is on or not. This confuses me.

Could a bad control module be causing this? The module came with a 25 amp relay, yet the instructions call for a 40/60 amp (so I'm a little confused here- why send a 25 amp-when the instructions call for a 40/60).

Any thought here before I load it up and haul it 50 miles back to the person who did all the wiring?? Sorry this is a long read.
Thanks
Larry

Re: Ignition switch failures.
 

If you're trying to run more than one fan from a 30A fuse that's your problem.

Re: Ignition switch failures.
 

We need more information to help. What control module are you referring to in statement #3. Please post the information on the fan controller and it's associated wiring. Is the fan controller starting both fans simultaneously or is it a dual fan controller with multiple temperature set points?

I believe the first thing to correct is the power to the ignition. You need to get it working correctly to start. It is possible that an ignition switch problem is tied into the fan controller problem.

Once that is done the wiring for the fan control circuit needs to be verified from fuse box through all wiring and components.

Personally your narrative brings several items to light that makes me question the quality of work done. The bad connection at the fan relay, the ignition power issue, the failure of the fan controller to operate, and the number of blown fues you have experienced.

When I do a complete or complex wiring job I always do resistance testing before applying 12 volts. Do you know if this was done?

Do you have a DC ampmeter? What kind of multimeter are you using? How much troubleshooting are you willing to do? Do you expect the installer to warranty their work?

Re: Ignition switch failures.
 

Are you referring to the purple wire between IGN switch and solenoid? If so, that seems awfully high considering GM used only 12 gauge wire with a 16 gauge fusible link from the battery to the fuse panel BAT bus, to the ignition switch, and then to the solenoid.

Conventional wisdom is 12 gauge stranded wire is good for 25 DC amps continuous. But, heck, it's easy to draw that much or more with coil, hi-beams, heater fan, and radio. Add in brake lights and miscellaneous stuff, and I don't see how those factory wiring harnesses lasted even 1 year, much less 30+ years like mine did. I worked in electronics for nearly 20 years, and I just don't get it.

Re: Ignition switch failures.
 

Yes the purple wires to from the ST terminal on the ignition switch through the neutral safety switch, through the firewall connector, and to the solenoid. It's no wonder GM vehicles of the era have hot start problems.

There actually are two coils in the starter solenoid. One to pull the contacts and the bendex in which is where the 42 to 48 amps comes in. Once the contacts and the Bendex are pulled in a different coil maintains the contacts and Bendix as long as the engine is cranking. I believe the hold coil amperage is 7 to 8 amps.

So the solenoid wiring will only see the 40 plus amps momentarily. (Unless there's a failure somewhere) With the exception of the headlights & brake lights the rest of the circuits in the truck are de-energized when the key is moved to the start position.

The thing to remember is GM is in the business of making money. So what might be unacceptable in one industry may be good enough for GM, if it saves a couple pennies per vehicle.

Re: Ignition switch failures.
 

One problem solved- spoke to Derale on the fan control module and vendor packaged the wrong control module with the dual electric fans. New fan control module on the way. We'll see if changing out the fan control module solves the issue of still running with the switch off.
Talked to the shop that did the wiring and he is going to drive over and got through the wiring to fix the issue with the starter switch.
Thanks for all the advise.

Re: Ignition switch failures.
 

WOW! That piece is fried!

Re: Ignition switch failures.
 

Motors can sometimes turn into generators. I worked on a car that would run for 4-5 seconds after the ignition was turned off. The fix was to install a diode between the trans cooler fan and an ignition voltage source. In this specific case, we were powering the fan from an aux fuse panel fed by the main fuse panel ignition bus.

I also had a similar problem with an alternator, where I had to use a diode in series with the exciter wire.