Ignition switch failures.
 

I am wondering if anyone else has had more than one ignition switch fail? I lost one in August of 2018 and one just yesterday. The truck has been driven just over 25k miles between the failures. Both switches failed at the solenoid connection tab. The SOL tab and the ACC tab become shorted together.
The truck has had a new under dash harness installed prior to the first failure. The charging system has been converted from the stock system to a CS130 system and the starter has been converted to a late model GM gear drive starter after the first switch failed. It has been more than a year since both of those modifications were completed.
Photos of both failed units. 1st and 2nd pictures are of the first failure. Third photo is from yesterday's failure.
Thanks in advance for any input.

Re: Ignition switch failures.
 

Just replaced mine a month ago, it appeared to be the original. My problem was it wouldn't automatically pop back from the crank position to the run position it would hit a dead spot and after the motor fired it would die, if I turned it back manually to the run or on position quick enough it would run no issues.

I replaced it with a Standard Motor Products P/N US84T
I also purchased just in case the pigtail plug-in ACDelco P/N PT1964 but mine had no issues so I stashed that in spare parts.

Re: Ignition switch failures.
 

you said you replaced the harness check the connector with it on the switch to see if those two are loose at all . i have had new female pins that were just enough loose to arc and heat the connection . being they got that hot it might be good to replace atleast those two female pins anyway

Re: Ignition switch failures.
 

Had to replace my original after 49 years. Put in a standard brand and it has failed to start 2 times lately. I was wondering if an AC would be better - heard they were mage in Mexico.

Re: Ignition switch failures.
 

The one that just failed was a Standard brand switch. I replaced it with an Echlind brand switch. I disassembled the switch and here is what I found.

Re: Ignition switch failures.
 

Go to post 761 in the link for my post on troubleshooting the failure.

http://67-72chevytrucks.com/vboard/s...698377&page=31

Re: Ignition switch failures.
 

wow i had not seen the other post before or those pics . i wonder if you might benefit from a remote solenoid to take some load off the switch . it seems with all you have checked and changed i wouldnt think wiring i would think the quality of the switches has gone down . i hope you keep a fire extinguisher handy

Re: Ignition switch failures.
 

Following up with this. BigBird05 was kind enough to send me a factory switch to disassemble and compare.
There is a difference in the design of the contacts and how they are operated. But there were some differences I noticed between the two that may lead to the contact failures
New aftermarket switch contacts are cone shaped compared to the factory's dome shape. Which seems to me the factory contacts definitely have more surface area conducting current. In addtion the higher amperage factory contacts are copper. (The 2nd photo doesn't show the difference contact materials very well.)
The other difference that was noticeable is the springs behind the contacts on the factory switch are at least 30 percent stronger.
In the 1st photo the arrow indicates the contact for the solenoid. The contact has a wider wear pattern with little indication of arcing. From the metal shavings it appears this switch failed mechanically not electrically.
In the 2nd photo notice the amount of arcing. It's easy to believe that would be enough to cause the wiring to overheat. The smaller contact area has some got to be a contributing factor. I also believe that stronger springs would help the contacts to clean themselves of arc damage when they pass over each other.
All comments are welcomed.

Thanks to BigBird05 for the switch!

Re: Ignition switch failures.
 

im thinking the factory one started out more pointed . the stronger spring and copper and 50 years made it into a dome shape but that spring probably kept them connected better so it didnt arc so much

Re: Ignition switch failures.
 

Mine would occasionally keep running when I turned the truck off :confused:

Then one bright sunny day when the birds were singing and the breeze was gently blowing, I started the truck and the starter kept going after the engine started then smoke started coming out from under the dash. :m3:

I flew out of the door and opened the hood ... luckily one of the battery terminals was loose enough to pull off with my teeth! :hc:

It only melted the main ignition wire slightly but the switch was pretty much toast .... even if it wasn't toast, it was going to be replaced. Summit Racing had some perfect plug and play switches, so I bought that one and then installed a fuseable link for the next time it decides to tries to self destruct!

Re: Ignition switch failures.
 

I would guess the issue is w/ lower quality aftermarket replacement parts in this case the switch.
The OP could run a relay for the solenoid, but I've run the solenoid off a 16G wire w/o an issue. The inevitable Ford solenoid suggestion is as always nonsense (IMHO).

Re: Ignition switch failures.
 

We've both had the same kind of excitement. :lol:
Where in the circuit did you install the fusible link? What guage fusible link did you use?

Re: Ignition switch failures.
 

I too am assuming the switches are the culprit and was hoping to confirm that with my post. Although it may not become evident unless the truck is a daily/weekly driver.
I have considered wiring a relay in to drop the load on the switch down below a couple amps. If I go that direction I'll be using a 40 amp Bosch style relay no need for a big ole starter solenoid relay here. :lol:

Re: Ignition switch failures.
 

After looking at your photos of the inside of the switch I am starting to see the merits of using a relay in the starter circuit. Do you have a part # for the Bosh 40 amp relay that you talked about? Also which contacts are the ignition on ones. Are they burnt just as bad? With todays increased load on ignition on voltage should we start thinking about more relays instead of just starter and head lamps.

Re: Ignition switch failures.
 

I think a relay would suffer from the same problem and self-weld the contacts together or contacts get burnt so bad they don't make contact any more. So, instead of relay, suppress the arcing by putting a flyback diode from the solenoid purple wire connector and ground.

Re: Ignition switch failures.
 

If you want the best, pick up an NOS Delco Remy switch from EBAY or other sources, preferably in a pull string can.

Part numbers to search for '67-'72:

1116683
1116688
1116695
1116704
1116709
1116711
1116712

Re: Ignition switch failures.
 

I couldn't find the 40amp I had, but here is the 50 amp version Bosch # 0 332 209 137


http://www.texasindustrialelectric.c...0332209137.asp

Re: Ignition switch failures.
 

Thanks I will do some research into flyback diodes.

Re: Ignition switch failures.
 

Thanks for the part numbers. I would rather have an OE switch than have to rework the system.

Re: Ignition switch failures.
 

I have had that happen many times over the past 15 years until I figured out the main culprit.

The heater fan. Turns on when keyed to ACC ON position. Are we correct so far?

Re: Ignition switch failures.
 

Had this happen also!

Re: Ignition switch failures.
 

I don't believe I specifically checked the inrush current of the fan during the previous testing. I will look into that.

Re: Ignition switch failures.
 

Test it on the high setting, you will find that those things draw as many as 40 amps or more depending on what is feeding them.

Higher output alternator is not helping also.

Since completely redoing the underdash wiring harness I do not run the fan on high. Have tried with a 10,15 amp fuse and I keep blowing them so..............

All the fan motors are coming from 2 sources now, and they are rated for both AC and non AC applications. Problem is the non AC truck wiring is only good for a 10 amp motor. Do not know about the aftermarket wiring so it sounds like you have to update that to accept the higher amp motors.

Re: Ignition switch failures.
 

I kept having ignition switch failure so I keep a spare in the glove box at all times. Son, Drew, re-wired The Rocket with a Painless Performance kit so I don't think wiring is the problem. Drew is meticulous with his work and understands electrical systems.

These switches aren't expensive and a spare makes for an easy roadside repair.

Re: Ignition switch failures.
 

The alternator is not an issue here as the engine is not running or hasn't been running long enough to start charging by the time the key is released from the start position. Actually wen the engine is running the newer alternator should provide better voltage control when amp demand is high thus reducing amperage draw across the board. It's that Ohms law thing, when voltage drops, amperage increases.

Heater fan amp draw doesn't vary much from low speed to high speed as the fan speed resistors add to the amperage drawn when they are energized.

Running the AC fan motor with up sized conductors will only lead to heater switch failure. (A lesson I learned the hard way many years ago on my GTO) That's why GM spent so much money designing and installing a A/C fan control relay in A/C equipped vehicles. Instead of up sizing the conductors to run the A/C motor is is much better to install an A/C fan control harness. Something that I am actually considering doing to my Burban. A Suburban has the same heater as a pickup but 4 times the interior volume to heat. I get plenty of heat but not much circulation. Which leads to whining from the back seats. An A/C blower fan may help me with that, but I digress.

I believe I may end to look into getting a different amp meter to troubleshoot this further. Flyback diodes may be a good addition to the circuit but I would like to have more accurate information on the circuit amperage before investing the time in adding them.

Yet another rabbit hole opens .:lol:

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.