Alternator Light, Electrical Frustration!

techguy · 08-01-2004, 06:52 AM

Hey guys, I have been trying to get some electrical issues ironed out in the car. It all started last year on a fun run when the car died. At first it looked like the points so I cleaned them, no luck. I then followed the problem to the Bosch Capacitive Discharge Unit and swapped it with a Permatune and matching coil from a guy in the PCA club with no luck. I then went back to the points and changed to new ones and she worked great. Only new issue was a bit more bouncing in the tach. That was last year....

This year I noticed the turn signal lights both coming on at low RPMs when turning.....well had this issue when I bought the car...solution...I cleaned the grounds, replaced the bulbs and the turn signal switch since it was falling apart. No more problem.

Continuing this year... the tach continues to bounce a bit and recently the turn signal indicators act up again. If I give the car a little gas the problem is gone. So I figure maybe the alt must be bad. I took the Marshall Alt in and found the bearings were fried and a few diodes were cooked so I had it rebuilt. The car has an external VR so I bought a new one as well.

Problem...indicator signals still flash at same time on occasion while turning and yes a bit of gas to bring the rpms up and the problem goes away. EVEN more important as of yesterday I notice that when I start the car the alt light comes on and only goes away if I give it a really good shot of gas and hold it for a sec...the alt light problem just started, the light has always been fine and for the last 2 weeks no problem since the rebuilt alt was installed. I thought maybe the VR was flakey so this morning I put in the old one and same problems.

Here is the voltage at the battery or the lighter, both the same.

battery with car off: 12.2 volts
battery with car running at 2000 RPM: 14.0 volts
battery at aprox 900 rpm idle with fogs, radio, headlights on: 11.90 volts

I can recreate the alt light easily by starting the car without a good kick of gas..eliminate the prob by starting and giving it a real kick of gas.

Do I pull the alt again and have it tested???? My grounds look pretty clean, mint at the alt and the fuse panel at the back. I might even try installing the old Bosch CDU again.

HELP!

scottb · 08-01-2004, 07:25 AM

Quote:

Originally posted by techguy
battery with car off: 12.2 volts
battery with car running at 2000 RPM: 14.0 volts
battery at aprox 900 rpm idle with fogs, radio, headlights on: 11.90 volts

That doesn't look right. Even with the load of the lights and radio, it should be putting out in excess of 12 volts...closer to 13. I'd double-check the quality of each ground, and then start trouble shooting the alternator....AGAIN.

Electrical gremlins are the worst.

Good luck!

RoninLB · 08-01-2004, 10:42 AM

Quote:

Originally posted by techguy

Do I pull the alt again and have it tested???? !

The field needs better excitement.. Early_S_Man and john_cramer will be able to give you a clearer answer and solution. Contact them if another pelicanhead doesn't jump in.

relax

techguy · 08-01-2004, 11:52 AM

Well, I decided to change the Permatune back to the Bosch and am happy to report nothing different. Good news is that last year when the car died it looks like it was the points for sure, I also know the old coil was a bit flakey but the one that came with the Permatune works great. I put the Permatune back in since I do notice a bit better performance with it...at least I have a spare CD box now. While back there I cleaned and taped the wires up a bit more, I do think the tach is a bit happier.

More info on the last post regarding," Exciting the field a bit more" would be great! It does make sense since the VR and alt are working great with the car runing down the road..its just a fresh start in the morning it needs that extra kick to iron itself out. I also wonder about the battery, it does sit for 2-3 days at a time, it was replaced last year.

ASD · ASD's Garage

I had the jumping tach syndrome, changed the vr it went away...for awhile. When it came back intermittently I tightened the belt, moved the shims,etc...it was gone again for a few weeks, then all of a sudden it started jumping again. Alternator? When it jumps its overcharging as much as 17 volts. All other times its reading 14 or so. Would bad diodes = overcharge? I was thinking bad alt would be undercharging instead. Oh yeah, when it jumps the gen light will blink on for a second or two.

lateapex911 · 08-01-2004, 07:54 PM

bump

Wil Ferch · 08-02-2004, 06:06 AM

Understand something....

"Battery off....12.2 V "....

your battery is at half charge.

Here's the profile:
100% charged....12.6 V
75% charged... 12.4 V
50 % charged...12.2 volts
25% charged....12.0 (-) volts
0% charged...10-11+ volt range.

---Wil

ASD · ASD's Garage

and from what I understand if it hits under 12v it will lose at least half its life expectancy , unless it is an Optima or similiar type.

RoninLB · 08-03-2004, 05:11 AM

Quote:

Originally posted by ASD
and from what I understand if it hits under 12v it will lose at least half its life expectancy , unless it is an Optima or similiar type.

really.. I'll have to look for hard info on that one. nice tip.

techguy · 08-03-2004, 06:58 AM

Good news, I do believe the theory regarding the battery voltage...more importantly its also the amperage available. I am willing to bet many of my short trips have been draining the battery so starting the car the alt light kicks in until the charge comes up. I have the battery on a trickle charge and its over 13V this morning and no alt lamp after startup. Of course this has all seemed to happen since the new alt and VR have been installed, always suspect the electronics after a rebuild. Tach is also working a bit better after reinstalling the Permatune and polishing up and re-taping the wires to the unit.