Neutral Safety Switch Failure? - Team Camaro Tech
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post #1 of 21 (permalink) Old Aug 27th, 17, 08:46 PM Thread Starter
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Neutral Safety Switch Failure?

Hello everyone. I have a '69 convertible with a hot start problem. When the engine has been sitting and is cold, it starts fine. Drive it around a bit and all bets are off. If it doesn't start, it clicks. I've already read a lot of threads here on this issue. I've replaced the purple lead from the bulkhead connector with a fresh run of #12 stranded wire. I have also moved the main ground from the aluminum head to the engine block. Some voltage measurements are as follows: Battery 12.97 volts. Purple (solenoid) wire not attached 12.89 volts. Solenoid wire attached; purple and white stripe wire (in) on pigtail for neutral safety switch 11.20 volts. Purple solid wire (out) 10.60 volts. Is a 0.6 volt drop across the NSS normal?

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post #2 of 21 (permalink) Old Aug 28th, 17, 08:00 AM
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Re: Neutral Safety Switch Failure?

From the points you measured, 1.6 volt drop - a lot of loss.
Think of the current as watts, i.e., Watts = volts X current.
Solenoid needs X watts in pulling closed.
If volts available drop, then current must increase for keeping the same number of watts.
Any connection with more than 0.4 volt drop across it is excessive.

You might do one of two things for troubleshooting, 1) use a remote starter button, 2) install a male-to-male coupler between the two purple wires on NSS.
If either one works, then too much drop of power, either at a connection, or too small gauge of wire.

You should measure the total drop of applied power from BAT pos post and S terminal post, not the terminal, but the post, in START position.
You be amazed of the drop. Separate the connections and wire brush them.
And do the same from motor case to BAT neg post.

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post #3 of 21 (permalink) Old Aug 28th, 17, 10:54 AM Thread Starter
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Re: Neutral Safety Switch Failure?

I'm pretty sure the NSS needs to be replaced. It's the best part of 50 years old and pretty dusty/dirty up there. As far as I know, they cant be taken apart and cleaned so I will grab one at NPD on the way home. What I'm not sure about is the ignition switch or even how it is removed. I made sure there was no paint on the block where the starter mounts.

69’ Camaro convt. Metallic grey, Blueprint Engines roller 383 stroker 445hp/465tq. Edelbrock Air Gap intake. Holley Terminator EFI. Hooker stainless headers. Tremec TKO-600 5 speed, 3.55 posi rear, Vintage Air, March Performance, TMI Interiors
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post #4 of 21 (permalink) Old Aug 28th, 17, 03:48 PM
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Re: Neutral Safety Switch Failure?

You may be correct on the 48 year old switch, how many times has it gone through neutral?
Ign switch on top of column and held in place with two screws and the actuator rod from the tumbler.

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post #5 of 21 (permalink) Old Aug 28th, 17, 04:39 PM
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Re: Neutral Safety Switch Failure?

Quote:
Originally Posted by JohnnyD View Post
What I'm not sure about is the ignition switch or even how it is removed.
The switch is held on with two small screws and after you unplug the wiring connectors, you remove the two bolts (I think they are 5/16" maybe ?) and the switch will lift up and off of the activation rod and then allow it to be removed from that area.





Years ago I wondered what was inside of the column switch so I took one apart from one of my 74's and this is what is inside of it:







There are short brass bars that have a rounded face and these are pressed downward with springs to make contact with the connections molded into the switches housing and I don't remember it being hard to take apart, you will spend more time cleaning the contacts and reassembling it AND if the contacts molded into the housing have too deep of grooves worn into them you may not get proper contact from the bars to connect to different points in the switch.

Be aware that there may be two different ignition switches available for your car. One with a tilt column and one without a tilt column. One switch has the activation rod off of the key tumbler going one way while the tilt column switch goes the other way.

Once you get the new switch in, the switch has slotted holes on it that the bolts go through and this allows for fine tuning adjustments.

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post #6 of 21 (permalink) Old Aug 28th, 17, 05:32 PM
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Re: Neutral Safety Switch Failure?

The ignition switch is wayyyyy more likely to be source of your trouble than the neutral safety switch. The NSS is almost always closed when current is running through it, hence no arc to carbon up the contacts. The ignition switch is always going from open to closed and back open with current running through it. Over time this arc will deteriorate the contacts, which increases resistance and drops voltage.

Do a voltage check on the purple wire to the solenoid when it's hot and won't start - you might see less than half of batt voltage.

Or the problem could be elsewhere.


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post #7 of 21 (permalink) Old Aug 28th, 17, 07:29 PM Thread Starter
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Re: Neutral Safety Switch Failure?

Wow! Thanks for all the great feedback and pics as well guys. My thinking on the NSS is because I can measure a voltage drop across the switch itself. Also, its in a dirty area. Don’t get me wrong, Im pretty sure the ignition switch is defective as well because the voltage coming into the NSS is substantially lower than the battery. Also, for every time the car is started and taken fir a ride, the NSS is triggered a few dozen times? Maybe 50? Maybe 100? Who knows. But for sure, it gets its far share of use and wear and tear.

Were the pics of the inside of the ignition switch? So if I replace it, cleaning or worn contacts wont be an issue? Thinking I should just replace it if thats the case.

69’ Camaro convt. Metallic grey, Blueprint Engines roller 383 stroker 445hp/465tq. Edelbrock Air Gap intake. Holley Terminator EFI. Hooker stainless headers. Tremec TKO-600 5 speed, 3.55 posi rear, Vintage Air, March Performance, TMI Interiors

Last edited by JohnnyD; Aug 28th, 17 at 07:43 PM. Reason: added info
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post #8 of 21 (permalink) Old Aug 29th, 17, 05:04 AM
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Re: Neutral Safety Switch Failure?

If the switch/contacts are the issue, why does it start fine when cold? Have you looked at the usual heat related starting problems, headers close to starter, bad solenoid, adding heat shield to solenoid etc.
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post #9 of 21 (permalink) Old Aug 29th, 17, 05:16 AM
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Re: Neutral Safety Switch Failure?

Well the simple test as to if it is the switch or heat soak is to do as Everett suggested, bypass the switch and test cold and hot.

Brian


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post #10 of 21 (permalink) Old Aug 29th, 17, 07:03 AM Thread Starter
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Re: Neutral Safety Switch Failure?

Some more info... The starter is made by Powermaster. I have talked with their tech department on the issue and they state heat soak is not an issue at all with their XS line. In fact, they claim that as far as reliability goes, this is one, model #9540 is one of their best. Also, they do not want insulating wraps/shields used as they tend to not allow heat to dissipate from the starter itself, or they tend to trap reflected heat from adjacent heat producing structures (headers etc). The headers are not super close to the starter. I did replace the run (purple wire) from the bulkhead connector to the starter and this may in fact have fixed the problem. I don’t know because I haven’t driven the car yet. But even so, if it did fix it, I think its going be a “band aid” fix because the voltage still appears marginal at the S terminal. Hence why I am looking elsewhere and was thinking at least the NSS because of the drop across it, and perhaps the ignition switch also because of the marginal voltage to the NSS. Not ever seeing an ignition switch, I don’t know if the wiring runs to it or if the key mechanism moves the copper contacts shown in those pics when the key is turned and the wiring runs to that. Im unclear if thats the case and if is this a replaceable item or something that at best can be cleaned with something like CRC contact cleaner. All those small parts and springs look like they just want to get lost. If I understand Everett’s suggestion for testing, it seems like a great idea; run a lead direct from the battery to the S term with a push button switch in line and measure the voltage drop. This would give an actual expected value.

69’ Camaro convt. Metallic grey, Blueprint Engines roller 383 stroker 445hp/465tq. Edelbrock Air Gap intake. Holley Terminator EFI. Hooker stainless headers. Tremec TKO-600 5 speed, 3.55 posi rear, Vintage Air, March Performance, TMI Interiors
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post #11 of 21 (permalink) Old Aug 29th, 17, 08:05 AM
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Re: Neutral Safety Switch Failure?

Quote:
Originally Posted by JohnnyD View Post
Also, for every time the car is started and taken fir a ride, the NSS is triggered a few dozen times? Maybe 50? Maybe 100? Who knows. But for sure, it gets its far share of use and wear and tear.
The point I was trying to make is that under normal operation the NSS isn't passing current. The only time current flows through that switch is during cranking. Think of the NSS and IGN as 2 switches on 1 wire. Both have to be closed to pass current. If one or both are open the circuit is electrically dead. When you shift gears you are operating an electrically dead switch.

Assuming you push the clutch pedal before you start the engine, the switch is closed. Once the engine starts and you release the key current quits flowing through that switch.

Opening and closing a switch with current flowing is what wears out the contacts. This happens to the ignition swich every time you start the engine and virtually never with the NSS.

Edit - While you're at it, clean the terminal block connection just in front of the battery and the two screw terminal connections on the horn relay bus. Those are both part of the same circuit and are prone to getting cruddy and increasing resistance/voltage drop.


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post #12 of 21 (permalink) Old Aug 29th, 17, 09:07 AM
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Re: Neutral Safety Switch Failure?

Quote:
Originally Posted by Grinder67 View Post
If the switch/contacts are the issue, why does it start fine when cold? Have you looked at the usual heat related starting problems, headers close to starter, bad solenoid, adding heat shield to solenoid etc.
Because when the windings in the starter solenoid get hot resistance increases. This is perfectly normal. An iffy switch (or other connection) can pass enough current to trigger a cold solenoid with "low" resistance, but not enough to trigger a hot solenoid with increased resistance. When you shut of a hot engine the starter is more likely to "soak" up heat from the hot engine block to which it is bolted than from a nearby header tube.

The entire circuit needs to be looked at, and this starts at the battery and every connection between there and the S terminal on the solenoid, including grounds.

Consider this - with the engine off and the key in the run position every single circuit in the car is fed through that little wire that runs from the positive battery post to the junction block just in front of the battery.


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post #13 of 21 (permalink) Old Aug 29th, 17, 05:09 PM Thread Starter
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Re: Neutral Safety Switch Failure?

Update: At some point I redid some of the wiring and one of the improvements I made was putting in a distribution block and routing all the high amperage items like the alternator, the run to the horn relay, sub amp, cooling fans; all with a minimum 10 gauge wire and from the distribution block to the battery with 6 ga. The starter motor and main engine ground are 2/0 ga. Yeah I know its total overkill. Anyway, I took some more measurements today: Current battery voltage no load - 12.98v Key on, starter motor disconnected, only power to the ignition side of the starter - 9.82v. NSS bypassed with a jumper - 10.46v. Momentary push switch direct from battery to the ignition side of the starter - 12.02 v. So, with the Powermaster starter, about a 1 volt drop is normal. Unless Im missing something, there is definitely subnormal voltage to the NSS and about a 0.6v drop across it. Cant see how the switch doesn’t need replacing. As far as the subnormal voltage to it, Im not sure if the key switch needs to be replaced or if all those copper contacts and springs are beyond it? Feedback please and thanks!

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post #14 of 21 (permalink) Old Aug 29th, 17, 07:49 PM
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Re: Neutral Safety Switch Failure?

The NSS is after ignition switch in the circuit. Even with the NSS bypassed you're losing 2.5V somewhere, and that I assume is when the solenoid is cold. When it's hot it's likely to be (quite a bit) more. Measure voltage at the 12ga red wire going into the ign switch and the purple/white coming out of it to see if you're getting significant voltage drop across it.

If you have low voltage into the ign switch, the next logical place to check is at the bulkhead connector, but it's a pain in the *** to check there. Check at the horn relay bus. If you have good voltage there, check at the junction on the core support ahead of the battery. If you go about it logically you'll find it - it could be a combination of dirty switches/cruddy connections. If your wiring in the car is still the original harnesses who knows what a p/o might have hacked with crimp connector (ugh!) and then covered back up with black tape. By checking at each connection you can narrow it down.

It would be interesting to disconnect the plug connector to the NSS and put an ohmmeter on it. If it's reasonably close to 0, clean the connectors while you're there and plug it back in.

As mentioned - the ign switch is NOT inside the column near the lock cylinder - it's on top of the column close to the firewall. The lock cylinder just operates a rod that goes down there to operate the actual switch. You need to drop the column down to access it - two 9/16 nuts after you remove the plactic trim piece. All those copper contacts and springs are inside the switch! I wouldn't even consider taking it apart and cleaning it, Id just replace it. A new switch isn't very expensive - about 20 bucks. I would trust NAPA Echlin for that part, not their cheapo brand. Just tell them whether or not you have a tilt column. I doubt a clutch switch is much either


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post #15 of 21 (permalink) Old Aug 30th, 17, 11:22 AM Thread Starter
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Re: Neutral Safety Switch Failure?

I been working since reading the last post. I did measure the resistance across the NSS a couple days ago and came up with zero which was a bit confusing considering the 0.6 v drop across it. Since I already replaced the run from the junction block to the horn relay, my $ is on the 12 ga. run from the horn relay to the bulkhead connector. I've already had that apart and have cleaned all the contacts on both sides of it. Unfortunately I used the last male terminal (engine side of bulkhead connector) and am gonna have to locate some. But before I replace the run from the horn relay to the bulkhead connector, I will check the voltage to the ignition switch. If voltage is normal there, the problem must be the ignition switch. All my connections are crimped and soldered. Hopefully no hacky connections elsewhere.

69’ Camaro convt. Metallic grey, Blueprint Engines roller 383 stroker 445hp/465tq. Edelbrock Air Gap intake. Holley Terminator EFI. Hooker stainless headers. Tremec TKO-600 5 speed, 3.55 posi rear, Vintage Air, March Performance, TMI Interiors
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