Is it my alternator? Voltage Regulator? Other?

[Mr Dark]

It's still a month or so until I bring my '85 out from its long winter nap, but I'll then have to deal with a problem that's been plaguing it since last year. Here's the scoop - When the car is idling, in gear, all of the lights seem to "fluctuate" in intensity. It's especially noticeable when the headlights are on. As you speed up, the problem goes away. The battery is good - it's less than a year old. The alternator reads between 14.2 and 14.5 amps. Is it the voltage regulator? I've seen the prices for alternators for an '85, so I'm hoping it's something cheaper. Thanks to all for any ideas you may have

 

[vigman]

That's somewhat normal... BUT

You need to clean/ check your ground's

Espically the frame grounds to engine grounds near the battery...

Check my post

"getting grounded" in the C-4 section.


Vig!

 

[Mr Dark]

I did a search on "Getting" connected with "and" to "Grounded" in the c4 section
(titles) and found nothing. Am I looking in the wrong place? Thanks for your input!

 

[c4ever]

I get the same slight flicker at idle with lights on. The readings you are getting are in line. If you're idling at 500-550rpm you'll experience a real drop in voltage reading with lights , wipers, etc running , somewhere below 12. When I did a complete idle, TPS adjustment to 550-600rpm at idle it cured this condition.
Always a good idea to do a check of all connections and grounds also.
Hope it helps some.

Carlo

 

[vigman]

Getting Grounded ( Whoops)

Gettin grounded C-4 1988

FRAME GROUND POINTS


G-401
Pass side door behind seat, behind plastic trim
About where the top of door line is.. ON THE BODY
10 mm bolt into frame metal, single wire.
This goes to the splice for grounding the entire ASS end of the car.

G-320
Left side of cargo compartment about where 401 lives on opposite side. ABS ground (total system)
& left side hatch strut for rear window defogger.

G-201
Is the ground for the entire cabin area. Behind instrument panel, left hand side, near steering column.

G-125
Pass side by toe kick panel,Dash grounds etc.

G-109
The Frame ground point for the AC Blower motor sensors & relays, spark ESC module, Washer pump.
On the frame rail, pass side, below the hi pressure
A/C cutout switches.


G-104 MAS IMPORTANTE'******************
The big gorilla from the Neg side of the battery
to the drivers side of the engine block with the ground braid & other Grounds!!!!
ECM,Fuel pump relay, Mass sensor & relays, tranny position Etc.

And

G-101
The little wire off the neg side of the
battery to frame rail & to Ground braid.This is the the ground strap.. the braided chunk of wire connects FRAME to ENGINE!!!!

G-115
Drivers side, foward frame rail, By horn.
Ground for headlight, horn, evap cansiter, turn & marker lights.

G-116
Mirror of G-115

G-117
Ground for Fan(s) & fan relays
By fan on frame rail twds pass side
on the cross member between the left & right frame rail on top.

This should be very similar for all c-4's but it's out of the 88 book.

Vig~

 

[vigman]

Some nice snaps too!

http://scotfab.tripod.com/old_proj7/old_proj7.html

Some good pictures of the frame ground strap & fixes. ( Forget the SIR part)

Vig!

 

[Robertwav1]

Yea...just may be that alternator. Had a car that did that one time constantly, changed the alt and all was well. Of course it had a built in reg. Check the grounds, replace reg and finally alternator. If it gets to replacement of the alt you already have a new reg which you would put in with a new alt anyway. My opinion.

 

[SPANISHVETTS]

Vig,
Thanks for reposting the ground info. I saved it to hard disk and printed a copy this time. 90% of all Vette electrical problems are due to bad grounds. My Alternator problem turned out to be a ground issue after all.

Mr Dark,
It’s easy to test your Alternator;
Start engine
Turn everything on. Radio, windshield wipers, AC, lights, etc.
Run engine up to and maintain 1500 rpm
Check the output at the +Alternator post. +/-14 volts OK less than 12.6 volts really dead.
Now put the voltmeter on the lowest VAC scale and check for AC voltage on the +Alternator post. Any AC voltage here is not good.

If the alternator is bad please try to wait a few days, I am looking at the Iceberg modification kit. If it proves to be as good as it looks it just might be a solution to our
C-4 alternator problems. As soon as possible I will post some facts about this kit.

 

[Mr Dark]

Thanks to all for the replies! It gives me some things to check. Spanishvetts - it'll be more than a few days before I can fix the problem; the car won't come out of storage for another 6 weeks or so (Minnesota winters are sooooooo long).

Do let me know what you find out about the Iceberg kit. I've never heard of it.

Vigman - thanks for the info and picture links!