# '67 GTO lights flickering



## pjw1967 (Mar 10, 2014)

https://www.youtube.com/watch?v=0ijp8l4siE4

Within the first 3 to 5 seconds after starting, the lights flicker. Every light. Headlights, dash lights, everything. You can see in the video that it takes a few seconds for it to start. Bringing up the rpm's smooth's it out but it is still discernable. I put on a new voltage reg and a new quality rebuilt alt. No change. Only electrical change to the car has been the addition of a column-mounted tach.

Has anyone ever ran a car with the voltage regulator disconnected? I don't think the ignition circuit crosses paths with it.

I intend to disconnect the tach, then the voltage regulator to see if it stops. If it doesn't then I will pull the fuses one at a time.

However, if any of you have experienced this, maybe you could point me in another direction first. Thanks as always.


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## rexs73gto (Nov 25, 2012)

Sounds like you have a loose ground in the system & the shaking of the engine is causing it to flicker.


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## geeteeohguy (Feb 2, 2008)

X2. Verify all 3 engine grounds, plus the dash grounds and light grounds. No such thing as too many ground wires. Add as needed!!


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## pjw1967 (Mar 10, 2014)

A grounding we will go, a grounding we will go, hi ho the derio....sorry, couldn't help myself. Thanks.


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## geeteeohguy (Feb 2, 2008)

LOL. I'm the same way....borderline Asbergers or Tourettes, etc. I 'lock in' on a song or a noise and go nuts. It's a lot of fun, though!! This morning, I have the song "Jam up and Jelly Tight", that bubblegum ditty from 1969, running thru my brain. AAAAAKKKK!!


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## pjw1967 (Mar 10, 2014)

geeteeohguy said:


> X2. Verify all 3 engine grounds, plus the dash grounds and light grounds. No such thing as too many ground wires. Add as needed!!


Which are the 3 engine grounds?


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## geeteeohguy (Feb 2, 2008)

There's a ground strap from the coil mount on the passenger side cylinder head to the firewall, anothe on the driver's side head to the firewall, and another that ties the frame and passenger side wheel house together. That, and the negative batt. cable to the cylinder head.


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## jmt455 (Mar 26, 2012)

There should be braided ground straps from the back of the cylinder heads to the firewall (one on each head), the large, black primary ground cable from the driver's side head to the battery and a braided strap from coil bracket to firewall.










Also, make certain the voltage regulator is well grounded to the firewall and the headlight switch is tightly secured, with the dash grounding straps (metal stampings behind the gauges) are in place and tightly secured.

Poor ground connections will cause ALL KINDS of weird behavior; have fun!


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## pjw1967 (Mar 10, 2014)

I will own this car 20 years in July and I have never laid eyes on any of these. Doesn't mean they are not there. Thank you all so much. Never too old to learn. Will report.


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## pjw1967 (Mar 10, 2014)

UPDATE. Fired up my Swann USB camera wand to go check for the engine grounds. Decided first to remove and inspect connection of Voltage reg to firewall. As I worked the 4 pin connector off, I hear "clunk", which was the sound of the capacitor landing on the cyl head. I Googled capacitor https://answers.yahoo.com/question/index?qid=20130519144051AAo4INM\
and it seems that this may be the cause of the flickering. Jeez, it gave out after 47 years. Will order a new one and see what happens.


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## pjw1967 (Mar 10, 2014)

Unfortunately, the hopefully quick fix of a new capacitor did not solve the problem. After seeing other threads about voltage regulators, I am going out to the parts bin to see if I can find an old one to install as a check. Meantime got the new Ames catalogue which advertises a solid state VR that looks like a mechanical one on the outside. They claim it is "excellent". Anyone have any experience with this? Thanks.


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## pjw1967 (Mar 10, 2014)

UPDATE: Haven't gotten to the parts bin yet. But I did remove each fuse, one at a time, to see if I could isolate a balky circuit. No change. 5 seconds after starting, the lights would start flickering no matter which fuse was removed. I found the ground from the coil bracket to the firewall, but I could not see the ones from the heads. Doesn't mean they're not there. So I took a heavy duty jumper cable, attached the negative wire to the neg batt term, and attached the other end to the underside of the dash. No change. It still could be the dash ground. I expect to pull the car out of the garage early this week to get at the parts bins. I also will pull the driver's seat out so I can lie on my back to get a good look at the dash grounds. PIA....


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## pjw1967 (Mar 10, 2014)

UPDATE: Don't get old. It's not for sissies. Did what I should have done at the outset. Unplugged the voltage reg and started the car. No flickering. Relatively new Duralast is bad. Just got off the phone with Ames. Ordered their $29 plus shipping solid state reg. Be here in a week. Will update again.


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## pjw1967 (Mar 10, 2014)

UPDATE: Got back from vacation and installed the inexpensive electronic regulator from Ames. No more flickering. However, the 4 plug assembly won't lock onto the reg. The second plug from the top has a little riser that slips under the flat ledge of the reg. It is supposed to pop up and lock the plug in. I can't seem to push it far enough in to get the riser to pop up. No big deal but I'll have to keep an eye on it to be sure it doesn't vibrate loose. If it ain't one thing it's another.....


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## jmt455 (Mar 26, 2012)

If the raised lock rib is too long to lock into the latch, just whittle a little off until it locks in place.

Glad the new VR solved the problem!


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## gr868 (Jul 29, 2013)

Just want to say thanks guys. My '68 gauges and headlights have been pulsating dim to bright. I just unplugged my regulator and it stops. I have a VR on order.
Thanks for the solution.


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## pjw1967 (Mar 10, 2014)

jmt455 said:


> If the raised lock rib is too long to lock into the latch, just whittle a little off until it locks in place.
> 
> Glad the new VR solved the problem!


Thanks. I took the VR off and "whittled" as you suggested. Not a lot of "meat" to whittle. Had to be very careful. Material was some sort of synthetic, not true plastic. Took a chunk out and the plugged snapped in.


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