Dash lights and acceleration

[Jeff Erwin]

Weird one. I was on my way home last night, everything running smoothly. There is a stretch of road that I like to let my Charger 'stretch' it's legs a bit. I jump on it, all three carbs open up, car does what a 440 6-pack should do at WOT then BLINK, all the dash lights go out. Turn signal indicators and high beam indicator work, interior lights work, nothing else amiss except ALL the dash lights are out.

I know, probably a fuse, which I will check this morning, but why would WOT cause the dash light fuse to blow (assuming that's the issue)??? As far as I know (and I rewired the entire car last year) there isn't a lot of connection between the dash lights and high RPM. Pulse from the alternator maybe?

 

[RemCharger]

Hook up a volt gauge, that will tell you if your VR is shot.

 

[Jerry Hall]

The only thing I can see is that the additional vibration upon acceleration caused something in the wiring to short or lose connection. I haven't looked at that particular circuit in the wiring diagram but lots of electrical issues are found in the bulkhead connections.

 

[Jeff Erwin]

Thanks. Checking there first.

 

[F4R/T]

Dash light dimmer old and has poor contact internally?

 

[dadsbee]

Tail lights out too? Same fuse... done on purpose so you know you have no tail lights.

 

[Jeff Erwin]

I checked the fuse for dash lights, it was blown, but replacing it has no affect. My gas gauge has also become intermittent, so I am starting to suspect the 12v regulator on the back of the dash.

I will check the tail lights.

 

[Nacho-RT74]

the cluster voltage limiter has nothing to do with the dash lights HOWEVER a missing ground could be affecting both. ALTHOUGHT 3rd gens gets a wired ground. Could be loosen while chassis ground is not being good enough. Rallye clusters gets a wired ground straight to the voltage limiter then the housing throught the voltage limiter attaching screw while is tight, while Standard clusters gets the wired ground to the PCB feeding everything

 

[Jeff Erwin]

Whelp, so far I have solved the problem, just not sure yet what caused it. The dash light fuse was blown. I replaced it with a chinese cheap fuse which lasted a while but somehow caused the taillight etc fuse to go. Replaced it, nothing changed. Realized I was using those cheap Chinese fuses with no back. Went to the auto parts store and bought a bunch of the expensive ones from Mexico with the fuse capacity on the back. Replaced both fuses and everything works.

Just not sure what caused the original blown fuse. I will wait and see if it happens again. So far only thing I can think of is either vibration or twisting from the acceleration caused something to short. Keeping an eye on it.

 

[Sinitro]

When pushing the engine the alternator/regulator had a high output voltage spike..

Just my $0.02..

 

[Rusty 72]

I had issues with my 72 and the dash light fuse popping. It was the cigarette lighter, wiring was cracked and bumping the metal dash, grounding it and blowing the fuse.
Follow the dash wiring and look for worn areas.