Ongoing Electrical quirks

I first picked up the truck in January, 160k, 3.4L XtraCab etc...

On the drive home, the battery light would come on and the headlights would dim. Get on the gas a bit and both would fix themselves. A friend and I tested both the battery and the alternator and found no problems. Battery appeared to be fine and the truck would run on just the alternator after pulling the battery. After a month, the issues hadn't gotten any better, but no worse either, every so often the light would come on, but it wasn't something I could voluntarily replicate.

I installed an amplifier and woofer, nothing huge, just a 500W peak/350W RMS. It worked fine for a few months up til now. Recently the sub would cut out while driving and then come back on. The light on the amp remains on. Its not the remote wire for the amp, i've jumped the battery lead with the remote to test that. All wiring hasn't changed and sometime works and sometimes doesn't. Yesterday, it just started now working at all. The light on the amp is still on and the fuses are fine.

I've got no other auxiliary lights/winch/gps type devices drawing any extra power.

Friend mentioned that it could be either a bad battery, or maybe a grounding issue for the battery. I've got two questions:

1. I know there are multiple locations for the battery to be grounded to the body/frame/engine block, but where are they?
2. Are there any other possible problems?

 

Thread similar to this not long ago.

First off get a step by step plan. I'd not worry about the audio until you have the electrical system nailed down.

Make sure all connections to the battery are clean and tight. Ensure the grounds are clean also. Check your power connection at the alternator (with the battery disconnected first) to ensure it is clean and tight. Don't twist it off though. Once you have verified all is good connection wise then have the system tested.

Do not test by yanking the cable off while the truck is running. Go down to your local Autozone/OReilly etc and have them hook up their tester. They will test the battery first. If the battery comes up bad then have it retested by itself unhooked from the truck. Still bad then buy a battery.

Now, if the battery was good or you've just installed the new battery because the old one was bad, you will want to have the truck retested. They will connect the tester up and have you start the truck. The test will be of the charging SYSTEM.

If they tell you that the alternator is not charging after doing this test don't immediately go out and buy one. The test they are doing is of the system not just the alternator. So, if you have a connection or wiring problem this can cause you not to get the charge needed at the battery also and will show a fault (bad charge rate) with the on vehicle test.

Verify all plug connections, belt okay etc. If all looks good then I'd suggest taking the alternator off (battery disconnected first) and have the alternator bench tested inside the store. Make sure to watch how it is supposed to be connected on the tester from the schematic they follow. Only say this as saw a guy ages ago who would leave off the ground connection so that he'd sell a part.

Alternator tests good then you have a wiring/connection problem. Tests bad then replace the alternator.

Once you have the electrical on the truck ironed out and working as it should then you can start looking at the audio. Do the big three upgrade (all over the web on how to). Make sure to have your wires fused at the battery and have the correct gauge needed as per amp specs. Run the wires away from any sharp edges and grommet where it passes through any bulkhead etc. Ensure good clean ground. Verify all wiring, specs on amp, load you've wired the sub to and ensure your gains are set correctly.

As long as your stock charging system can keep up with the demand needed for the added audio you should be good to go. Just remember Safety! on any installation.

 

Thanks for the replies. I'll have to follow that procedure when I get a chance.

I'm sure the audio stuff is fine, I had this exact setup in previous vehicles. It was just to aid the diagnosis of the overall issues.

 

Just wondered what you found? Any update?

 

I took it to VIP and had them hook up their tester. Came back all systems go. Battery is putting out better then the rated amperage. Alternator is working both at idle and under load (high beams, fans at high, speakers going minus the woofer). He asked why I brought it in so i told him and he said it could be the regulator. I'd pull the alternator to test it but I don't have another ride other then a pedal bike and I don't have that much time.

 

Thanks for the update.

Okay, fresh perspective. I'll go two ways here. Audio system. You could have an amp problem or signal problem. Power light could still be on, but internal issue to the amp where it does not put out or it isn't getting signal to amplify. I assume it does not work at all now from your post correct?

Verify main fuse on the power wire to it and ensure the amp has a good solid clean ground ground. Might want to disconnect the power wire both ends and use a meter to check for continuity to ground on the wire to make sure no issue with shorting.

Hook everything up again and remove the sub wires from the amp (label where they go first to make sure you get them back in the same spot). Place the meter on voltage and put the +, - probe ends in where the speaker wires go on the amp. Turn on your audio system playing a 50 hz tone (can download online and burn to disc if needed as loads out there) and see if you get voltage output. Theoretically, if gains set correctly and amp is rated accurately, then at 350 watts at a 4 ohm load rating you should show 37 volts or so. If that is a 2 ohm rating then it should be more like 26 volts. Voltages are at full unclipped power. Again, if amp over rated then will not put out as much. Point is, if you measure say 19 volts, to pick a number, you still know your amp is putting out power.

So, power and ground wires good to amp. Amp tested on speaker wire outputs with system playing and you have no output voltage from the amp. Next thing I'd check is the RCA input cables. Turn everything off, pull the rca cable off of the amp and connect the - to the outer ring on the rca and the + to the centre pin. Make sure not to arch them together! Set to voltage again with a range that covers 1-4 volts. Turn the system on and see if you have voltage on the rca as you turn the volume up.

No voltage then do the same test, but test the plug in for the rca to the sub on the back of the head unit.

No voltage, then issue with the head unit or the sub output is turned off or gained down on the head unit.

Has voltage (many are still 2 volts max output so even a measure in the 1.xx volt range is output needed), then rca cable is probably bad.

If on the speaker wire test at the amp you did get voltage output then something is wrong with the wiring to the sub or the sub itself has a problem.

Second direction, alternator.

Alternator could be testing okay with stock stuff and load including the load of standard speakers.

Is the battery light still flickering on with the sub amp not operational?

Charge could be within range. BUT, depending on alternator actual output/rating, when load of the sub is put on it the current draw added is too much for the alternator to keep up with. The alternator is supposed to run the load draw under normal operation while also replenishing the charge to the battery to replace the amount used from starting the vehicle. If the total draw on the system is higher than the alternator can produce then power will be drawn from the battery. If this continues then your battery/charge light will flicker on.

Hope that all makes sense and helps.

Reminds me of my first system ages ago. Had two punch 150's (yes that old) running 4 15's. All on a '75 Camaro with stock alternator etc. Driving at night, come to a light and the headlamps would dim and the charge light would flick on with the bass.

 

The amp does still work, sometimes. Sometimes when I hit a bump, or sometimes cruising on the highway. It's not regular and I can't make it work not can I make it stop working. Seems completely random. It works maybe 5-10% of the time.

Yesterday, it worked coming off an exit ramp, then it shut off, then the battery light came on.

For a short time, before it got bad, when I would crank the system, it would come on. I'd turn it back down to normal volume and it would shut off again. Crank it, on. Lower it, off. That doesn't work anymore.

I had a friend tell me it could be a bad ground on the battery. Apparently the battery is grounded to multiple points, fenders, frame, engine etc. he said if any one of those is bad, it could effect whatever is also grounded to those points. If the ground to the body is bad, the ground for the amp to the floor could essentially be worthless.

Not sure where those ground locations are but I'd check em if I knew.

 

sounds like bad ground, where did you ground the amp?

 

drivers seat rear passenger bolt. The light on the amp stays lit the whole time.

 

The sub ended up being bad. Replaced that and the audio works very well. I still have the occasional battery light and dim to bright headlight symptoms. I'll wait for more issues to arise before swapping out any parts or checking further.

 

I have a similar issue with dim lights. Have you found your solution? My batt light doesn't come on though.

 

http://youtu.be/FTGz0PKIl84

 

I had taken the truck to VIP to have the electrical system checked. Everything checked out according to their test. They asked why I wanted it checked so I told them the symptoms. They said it could be that the regulator in the alternator could be going or gone. I didn't do anything after that. Got a new subwoofer to replace the bad one as mentioned in a previous post and haven't experienced any issues since. Not even the dim lights.

 

You've got either a poor connection at one of the battery cables, a poor connection between the alternator and the battery, a poor ground or a bad alternator. Given that folks have repeatedly checked the wiring, my money is on the alternator.

One thing that comes to mind that might be intermittent (that I've personally seen on other vehicles) is the possibility that the positive cable running to the starter motor could be ever-so-slightly shorting to ground as the vehicle goes over bumps in the road because it's routed against a sharp edge somewhere. Ford diesels had this problem and it was the subject of a recall. I saw a Chevy truck that had just undergone a tranny overhaul get the positive cable pinched between the tranny and the motor. Check the cables from end to end and everywhere in between.

 

You can remove the alternator and have Advance Auto bench test it, I prefer this than have them test it in the vehicle. I'm taking one to get tested today from our Cummings diesel.

 

Yeah, but an alternator with an intermittent problem (regulator?) will test normal whenever the problem is not happening.

 

I believe if it has a internal regulator a benchtest would show it, I'm not certain on this just going by what my dad has explained to me. Advance Auto could not test my 160amp Cummings alternator You need to put a load on it to test it properly though.

 

Pulling it and taking it in was never an option as the truck was my only transportation. I picked up a cheap car to help on gas to my new job so once that's on the road I'll be able to pull it to finalize the problem. I haven't noticed any symptoms in a couple months now. I had even forgotten there was a problem.