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Intermittent full electrical power outage
#1
Well it seems the old girl is "powering down" on me occasionally now. Has happened 3x now while driving. At low-speed or idle, but in-gear. Car is C4 auto trans.

Symptom is complete power outage. Engine immediately quits, radio, lights, other internal electrical also go out. In all cases, after a few mins (usually including several shifts of the gear selector trying to get it restarted), everything comes back and behaves normally.

I'm wondering if this could be NSS related? Car is known to have occasional issue where shifter needs to be pushed full fwd to get NSS lockout to allow starting.

Q's:
1) Can NSS this be the issue? Situation occcurs in Drive most frequently
2) What else can cause a fully recoverable power outage like that?

Thanks in advance for some guidance/help here...

Jay

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#2
If wired correctly the NSS provides an electrical path from the ignition switch start position to the "S" terminal on the starter solenoid when the transmission is in neutral or park and that is the only time it has any electricity in it. The backup light section of it has a hot lead connected to it, but only runs to the backup lights when the transmission is in reverse.

You most likely have a loose connection someplace, and I would check the ignition switch and the battery/starter solenoid connections first.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#3
Don C;286104 Wrote:If wired correctly the NSS provides an electrical path from the ignition switch start position to the "S" terminal on the starter solenoid when the transmission is in neutral or park and that is the only time it has any electricity in it. The backup light section of it has a hot lead connected to it, but only runs to the backup lights when the transmission is in reverse.

You most likely have a loose connection someplace, and I would check the ignition switch and the battery/starter solenoid connections first.
+1. I'd also closely check the main grounds: battery to engine block, along with the battery post connector.

Let me check your shorts!
http://midlifeharness.com

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#4
Battery cables are a good place to check. Turn on the lights and tug on the battery cables and see what happens.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

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#5
Thanks. Copy that. I'll follow up when I get more info...

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#6
Justin,

I think you either have a loose power connection to your ignition coil or you have a short (i.e. 12V hitting a ground) somewhere in your system.

The power connection to the coil is a fun one because it comes from 2 sources depending if you are cranking or running, but that would be my main guess.

Ken

-Former 70 & 72 Mustang Owner.
-69 Torino GT, Formal Roof, 351W, Edelbrock 600 cfm, Edelbrock 351W Performer RPM intake, headers, AOD trans, dual flowmasters w/H pipe, Pertronix II Billet, 3.5 TRACLOC g/r, 15" Magnum 500s, 100A alt, aluminum radiator, electric fan, Pro-car seats, mini-starter...owned since Dec 13.
-70 Mach 1, 351W, Edelbrock E-Street EFI, VHX instrument cluster, Hooker headers, dual flowmasters, Pertronix II, 15" Magnum 500s, 150A alt, aluminum radiator, dual electric fans, Pro-car seats, mini-starter
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#7
I was having similar issues where mine would not want to start and I'd noticed that nothing else seemed to work - then it would randomly start working again for no apparent reason. It never shut itself off when it was running, though, but the accessories would or wouldn't be working.

I solved my issue by insuring the starter solenoid had good ground contact (where the backing plate and bolts meet the apron mounting point). Haven't had an issue since. I also cleaned the contacts on all the cables as well.

Eric

[Image: mach1sig2.gif]
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#8
Maybe a grounding strap between the motor and the car body if you haven't got one already.

-john
(jbojo)
351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,
C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

Some Mod pictures can be seen at:

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#9
Thanks for the help guys. No more evidence yet as I keep experimenting. These problems that pop up randomly are slow to troubleshoot!

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#10
I had the same problem with a Mach 1 I had long ago. It turned out I was missing the ground strap between the engine and body (as previously suggested). The electrical system was grounding through the drivetrain, and when I developed a bad u-joint, power would intermittently drop out completely if the internals of the u-joint broke contact. Moral of the story is, check your battery to engine and engine to body grounds, then check your u-joints. thumb

Steve
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