Dimming Headlights?

[mac911]

I am currently outside the US and unable to get to the car for more info, but the last time I was home I took the car out at night for the first time.

Cruising down the highway I noticed the headlights would dim periodically and then return to “full power”. Not sure if this is common for these cars, or if perhaps it can be attributed to bad wiring or the alternator… (I suspect it is not the alternator simply because the wife starts the car once a month while I’m gone and it fires right up.) Also seemed to coincide with the fan comming on.

No hesitation in the throttle, so I’m leaning more towards an electrical issue than anything to do with the motor… but have been known to be wrong before!

Car has Twilight Sentinel (T82) if it makes a difference and was in the off position.

Any idea what could be causing this?

Brian

 

[novaderrik]

if it happens when the fan comes on, then it's just the load from the fans dragging down the electrical system until the blades get spinning.. could also be a bad voltage regulator inside the alternator and a weak connection on a ground wire or something silly like that.

 

[longball]

Cruising down the highway I noticed the headlights would dim periodically and then return to “full power”. Brian

Had my alternator 'cleaned up and rewound' to 180A. No more dimming headlights no matter what I turn on.

 

[mac911]

So it may be worth a try with a 140 amp alt?

I'll also make a note to check an clean the ground connections.

On a somewhat related note, would a frayed positive battery cable coming off the battery terminal have anything effect on the alternator producing enough amps for the electrical system? I have new cable (pos and neg) to change out when I get home anyway. Just a thought...

Thanks for the help guys.

 

[longball]

So it may be worth a try with a 140 amp alt?

140 amp should be plenty.

I'll also make a note to check an clean the ground connections. On a somewhat related note, would a frayed positive battery cable coming off the battery terminal have anything effect on the alternator producing enough amps for the electrical system? Thanks for the help guys.

seems like anything is posible with the 'electrical gremlins'. be sure everything is clean, grounded correctly, and nothing should be frayed.

 

[mac911]

Thanks longball....

I have noticed the "Gremlins" seem to be out in force recently from the topics on the forum... just hadn't run across my particular breed yet.

Thanks again,

Brian

 

[Chuck Leeper]

So it may be worth a try with a 140 amp alt?

I'll also make a note to check an clean the ground connections.

On a somewhat related note, would a frayed positive battery cable coming off the battery terminal have anything effect on the alternator producing enough amps for the electrical system?

Thanks for the help guys.

The frayed wires will impose more load on the wires that are still connected at the terminal. If it's in that bad shape, what does the charging wire look like?
Appears that it is time for you to do the install, clean all grounds, and do a system voltage drop test.
have you noticed the + cable hitting the down pipe? That'll do it.
The ground cable under the turbo HAS to be tite...Another ground point to check.

 

[mac911]

good info chuck...

I will make a note of the ground under the turbo. I'll have to check when I return in the next couple months....

The only frayed wire I saw was the positive wire on the battery terminal itself. was not touching the downpipe though. actually not touching anything.

With a primarily stock car, running not additional elecronic equipment should there be any type of drop from the alternator?

I'm thinkin' no!

 

[Red C5]

The frayed wires will impose more load on the wires that are still connected at the terminal. If it's in that bad shape, what does the charging wire look like?
Appears that it is time for you to do the install, clean all grounds, and do a system voltage drop test.

That's what I was thinking too.

Peter

 

[davelostmissing]

Measuring the voltage during these "dims" would let you know if its system wide or maybe just headlight wiring/connections.

 

[mac911]

All good info, I have plenty of time to worry about it!

Thanks all.