El Camino Central Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1
On '85 Elky:
--has new battery, starter/solenoid, hot battery cable.

Very recently, I noticed that, when I put the car in reverse or hit the brake pedal, the instant either of those lights is activated, I see a very quick blink in the headlights. Just one blink...no extended period of dimming of the headlights. There is no 'reverse' blink when exiting reverse and/or releasing the brake.

Last night, I noticed that the volt gauge was reading well below normal for a period, but after a few miles, seemed to get back in normal range. (While I was driving, I had the headlights on and the heater blower on low...nothing else).

Prior to a week or so ago, there was no evidence of this situation at all.

Is it possible this is a first sign of a diode in the alternator about to let go??

Any clues or recommended places to start looking??

Thanks in advance...this has always been a great source of info...from the 'been there, done that' crowd!!

Taj
 

·
Banned
Joined
·
881 Posts
Sounds like the alternator. My 86 MCSS did the same thing but I ignored it for one day too many. :-( The low voltage usually indicates that the alternator output is too low and the engine and accessories are running off of the battery voltage.

Some may disagree with this test but it works for me so use your discression. Start your Elky, then remove the negative battery cable from the battery. If the engine shuts off then your alternator is probably bad.

My $.02

:mrgreen:
 

·
Registered
Joined
·
276 Posts
Please don't disconnect your battery cable while the engine is running! You can spike your alternator and/or your ECM. A spike can burn a diode in the alternator, of worse yet, blow your ECM out. $$$$$$ If you don't have a volt/ohm meter to check alternator out-put, a simple test can be done to see if your alternator is charging at all. Take a hack saw blade, a feeler guage, or any thin piece of metal and touch the back of the alternator on the bearing cap. If you feel a slight pull of magnetism, your alternator is probably charging. Of course it won't tell you how much, but it is a less risky way of checking it. Lights blinking can also be attributed to poor grounds. Check the ground cables from the battery to the engine, from the engine to the firewall, and if it has one, from the body to the frame. If you've recently painted your engine or engine compartment and didn't clean the contact area when you reconnected your ground cables, you're probably causing momentary loss of the ground paths. A poor connection of the large wire on the back of your alternator can also create the problem you have. I've found the wire actually broken at the terminal with the insulation jacket still holding it together. Good luck, and let us know what you found.

Orfunauto
82 SS
 

·
Registered
Joined
·
48 Posts
Discussion Starter #4
Thanks

Thanks for the tips, guys!!

I think I'll pass on the neg wire disconnect trick...sounds like I could do more harm than good.

I'll try the metal-on the-rear-bearing-cap trick and see what it does...and I will check all the grounds mentioned, as well as the battery and starter connections.

I do have a volt-ohmmeter...so if there are suggestions on how to test the alternator while running (not driving, of course...LOL), I'll try that too.

Tonight, I drove about 20 miles. When I started, there was no blink in the headlights when I put in reverse or hit the brake...and the volt gauge was looking just fine at just above 13 volts. By the time I got home, it was doing the 'blink thing' again'. It appears there is some 'leakage' somewhere while driving such that the alt is not charging the battery as much as it should. Could even be failing brushes in the alt...I have never had them replaced...original owner; Elky has 152k miles.

It appears to be a problem that is exhibited or magnified only after running a while...which tells me heat (and maybe vibration too) may have a role in this.

If I recall, diodes either work or don't...no in between. Am I right??

Lisle makes a nice inexpensive on-car alternator tester (similar to the J-tool that appears in the GM service manual) which I will try to get and use.

I'll report back as to what I find from the tests above...but would appreciate volt/ohmmeter test procedures so I can do that too.

As we have threat of snow and ice here, it may be a coule of days before I can do this.

Thanks again.

Taj
 

·
Registered
Joined
·
276 Posts
To check for charging rate using a volt/ohm meter, attach the positive lead to the battery positive post and the negative lead to the engine. Set your meter to read volts in the 20 volt range. The meter should read in the 13 to 14.2 volt range if the alternator is charging properly.
You said everything works fine until the car has been driven a while. This indicates that you may have a heat related failure. Loose conections show up more frequently when heat is involved. Failure is usually from high resistance - LOOSE OR POOR CONNECTIONS - (hint-hint) are usually the culprit. Good luck, and let us know what you find.
 

·
Registered
Joined
·
2,921 Posts
I had a problem with my 93 pickup once that was close to the same. I could hit the brake and it would trigger the interior light circuit. So for the next minute the interior lights would be on. My alarm has a timer for the interior lights. Anyway it drove me crazy. Finally one day I was going fishing and noticed the trailer light harness was bare in places. I replaced that and never once had the lights come on inside the truck again.

My guess was that somehow the wiring in the trailer harness was creating a bad ground or shorting just the right way which spiked the electrical circuit triggering the interior lights.

Just a thought.
 

·
Registered
Joined
·
1,325 Posts
Since you have a multimeter, simple diode check is to read AC voltage at the alternator output terminal. That's "ripple" voltage and should be less than 1V.

Generally the diodes, voltage regulator and brushes are all in one assembly (in a one-wire alternator) that can be replaced without getting a whole new alternator.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #8
The Final Verdict

First, I want to thank all who replied to my initial post.

The fix was as easy as it gets: very slightly losse connection of ground wire at battery post.

It needed maybe a 1/4 turn of the bolt.

There has been no blinking of the lights since then.

For good measure, I tightened the hot lead at battery and solenoid as well as the ground lead at the battery and alternator bracket.

All is well with the world now.

Again, thanks to all!!

Taj
 
1 - 8 of 8 Posts
Top