Del sol - headunit cuts off then turns right back on and headlights dim
 

93 del sol, d16y7, 5 speed all original. Lately, ill be driving, and my headunit will cut off then turn right back. Ill be driving, and for no reason, it just cuts off and immediately comes back on. Ive had the alternator, starter, and battery all tested and it passed. I then checked the alternator belt and it was "slightly" loose. So I tightened it a bit drove on it and had no issues. However, when I came home last night I let the car idle in my driveway with everything on(running lights, headlights, etc.). After a few minutes of idle the headlights dim, and the car dropped idle but goes back to normal. Im kinda stumped here. Early warning sign of the alternator going bad?

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

What are the voltages across the two battery posts with the warm engine idling under no electrical load versus high electrical load (high beams, A/C max, rear window defogger)?

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

yeah or you have a wire that is causing you to short out. Ex-gf has an issue like this but the car would just shutoff after 5 mins of idle/drive, It was a loose wire...:S

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

I will check and let you know. Theres no issue when its during the day. Before I tightened the belt id shift from 1st to 2nd and as im accelerating I could feel the car losing power
. Now, it hasnt done it lately. At night even when I had the headunit off, I was letting the car idle with the headlights on and youd see them dim then come right back.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Going to use the volt meter tomorrow. What should the voltages read on the battery while the car is under no load vrs a load?

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

14 under no load. 13 under a load. High beams, blower motor, etc.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Give decimal values. 14 point what? 13 point what?

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Why would that matter? It stayed a solid 13 and 14. Between 12 to 15
so that says its not the batt.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

The decimal values are important. For example, if your reading was 13.0V under load, then the alternator is shot. If on the other hand your reading was 13.8V under load, then the alternator is fine.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Ok. Makes sense. Ill check again. Keep in mind that it doesnt do this all the time. Just occasionally.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

14.1 no load under a heavy load 13.1-13.5

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

12.8. Slowly decreasing.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

13.1V in this test is too low. Suggests alternator problem.

Heavy load?

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Yes, under no load it stayed a consistant 14.1. Under a heavy load(blower motor all the way on, headlights/high beams, radio, etc.) it started at 13.6 then slowly decreased 13.4, 13.2, 13.1, etc. Then made it all the way down to 12.6. I'm replacing the alternator right now...

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Easier alternator test:

Unhook your battery cables while the car is running
If it dies or dims pretty quick, it's definitely the alternator on the way out
If there's no difference in lights dimming, might be a wire loose somewhere
^^;

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

I totally forgot to do that. I put the alternator on and it seems to be doing ok. I will keep you up to date if anything persists. I really appreciate the help, Ron. Thanks.

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Yea sounds like an issue with the alternator which is causing you to loose power...Should look into a new one...GOOD Luck

Re: Del sol - headunit cuts off then turns right back on and headlights dim
 

Never do this test. It risks damaging sensitive electrical components.