peelsSC300

iTrader: (1)

When ever I hit the breaks, turn on a/c, move the seats, use turn singles or anything that uses any sort of power., all my lights flicker, radio cuts off and the car acts like it wants to die. This has been going on for months. The problems have started about two hours after I put some subs in after a good bass note. So I double check all the wires, all was good. Had the battery tested, it was only showing 40%. So I replaced the battery and alt with new parts. That seemed to work for about 3 days. So I just completely took out the entire sub setup and pulled the out the fuse for the amp wire. Now, the problem seems to getting worse. Whenever I am at idle, all my dash back lite lights flicker like crazy, idle bouncing all over the place. Ever now and then my VCS, ABS light will come on, but, I replaced the unit last year with a known working one. Could I be having ECU problems? I don't have any check engine lights that come one. How can I get the ECU tested? This is my wifes car, so I would like to get this fix ASAP before she makes up her mind and wants to trade it in. (car is paid for, don't want any payments)

Bhubb18

I would check the alt again, even though said you replaced it

wbmx1981

brush the battery wires with a wire brush.

peelsSC300

iTrader: (1)

Yea, I was going to pull it off this weekend and have it check

Both conections are new as well. But I'll double check em.

CleanSC

Classic bad ground or corroded battery cable. Symptoms indicate very low system voltage.

Look hard in this area. You may have left a larger cable loose.

Recheck alternator connectors, battery cables, and main battery ground. Load test the battery and alternator.

Is this a nothern car with corrosion issues?

peelsSC300

iTrader: (1)

As far as I know, this car has never "lived" pasted South Carolina, I'm currently in Georgia. Both battery cables seem fine, I did replace the connectors when we first got the car as they seem to be a little rusted. I'll replace the cables and recheck everything just for safe messure. I did a load test a few days and think it read 14.3 volts. It's just a little mind blowing that non of this was happening, until that first big bass note drop. (damn you lil john!!!)

CleanSC

The issues starting after a Lil John "WHAT??" would indicate that a large current draw caused this problem. A hard bass drop would pull maximum amps. This may have been the last straw for any weak ground or corroded connection as the resistance caused by a poor connection would heat up to the point of failure.

Check the alternator fuse or fusible link. It may be half melted. Google what voltage drop testing is and start testing key connection points like alt. to batt. on both positive and negative sides. Do the same for grounds as such battery to main ground point, batt to chassis, and batt to engine.

My money is on a bad/loose ground or a ground you forgot to reconnect.

How does the car start? Nice and strong? Or weak with dimming lights/radio?

What's the system voltage read at the battery when the car shows the symptom?

peelsSC300

iTrader: (1)

Nah, it started after a BIA BIA!! The car starts perfectly fine. The DRL's and headlights are very dim. At night, they don't even look like they are on sometimes. I'll play around with her ground wires this Saturday and report back. Thanks for the tips. I hope it's something as simple as a ground.

CleanSC

If the car is starting ok then your battery, battery cables, alternator, and battery ground to starter are ok. The starter places the single heaviest load on your system than anything else in the car.

So if it handles a huge current draw like a starter motor and struggles to light a DRL, this is further evidence that you have a bad ground somewhere in the secondary circuits.

I've had a customer car with a badly corroded ground due to front end accident. It basically rusted thru and was completely disconnected. The ground was up front by the headlight. The car came in because every time she activated the turn signal on that side, the car would shut off. Like clockwork. Same would happen if she turned on the air. Bad ground on an unrelated circuit would shut the ECU down and poof. Car was dead. It would start right up after.

Moral is, if your grounds are not doing their jobs, WEIRD ISH happens.

For this entire time, (a few months, correct) you have never had to charge the battery, correct? And it's always started just fine? Just making sure the charging system and related high current cables are good.

If you really want to tackle this issue yourself, get a digital volt meter and the electrical diagram for the car. Do the voltage drop tests I spoke of eariler. Also with the car running, check the voltages of each main circuit in the car at the fuse box. Just touch the probe to the top of the fuse at the exposed metal portion.

Write down all circuits (while they are running/turned on) that are lower than system voltage. See where each of these is grounded. Chances are they are all share the same ground. If so, bingo. Check that ground. And not just the connection to the body. Check the entire wire. This is done with voltage drop testing (again, while the circuits are on).

peelsSC300

iTrader: (1)

Man, I wish you were here in GA. Yes, during all this mess, I've never had to have the battery re-charged and car start with no problems. Except for one time, the wife said the car cut off on her once on the way to way. Of course, she didn't tell me this until almost a week later and couldn't remember what she was doing to cause that. I have yet to be able to duplicated the problem.

Hopefully, I should be able to tackle this problem with a buddy. Thanks for all tips again.

adolfsonzp

It's just a little mind blowing that non of this was happening, until that first big bass note drop.

peelsSC300

iTrader: (1)

Ok, wasn't able to get any volt readings done today. Buddy with the tool, wasn't able to come out. However, I did replace the neg cable coming from the battery to the block and replace a few fuses that were the wrong size. The fuse for the alt had a 100a instead of a 120a. A few small bus fuses were 10's in stead of 15's. To no surprise, problem still exist. I'm just going to take the car to a shop tomorrow and see if the can diagnose it.

Question: Does the neg cable from the battery need to be grounded to the chassis and block? The old cable was ground to the chassis and block. The new cable does not split off for a connection to the chassis. Will I be ok with it just being ground to the block?

CleanSC

LOL you're kidding right? No, that's not okay. I've said to check that EXACT ground a bunch of times.

You NEED a main battery ground and you removed it. Of course you're having these issues. You're trying to ground the entire car's secondary circuits thru motor mounts made of rubber. Not gonna happen.

Install a large gauge negative cable from the battery's negative post to the chassis factory ground point. Problem solved.

peelsSC300

iTrader: (1)

I just changed the neg cable yesterday, the problems I had before, are still there. I was just asking if it was ok to only have it grounded to the block(no rubber is there), instead of the chassis and block. If need be, I can splice the new ground wire to the chassis and block.

CleanSC

Like I said above, you have to have both. Without the chassis ground, all the car's electricals are trying to ground thru the battery thru the engine. The engine is connected to the car with rubber engine mounts. Rubber sucks at conducting electricity.

The electricals should be ground directly to the battery with a main battery to chassis ground. Without this cable in place, you will have these problems you are describing.

The one ground you do have right is for the starter and alternator, that are placed ON the engine and isolated from the rest of the car. This is why they are working perfectly.