Hey guys,
I have been starting to trace some voltage issues I have been with having my HID's kick on but have all the numbers at home. Im basically thinking my contacts in headlight switch are burnt and HIDs take such high current to light that it will ever only light one of them. On the wiring diagrams it looks like a straight circuit with no headlight relays, only one prior to the switch. If you unplug one headlight harness, the other one will light, obviously, and likewise with the other side. But if both harnesses are plugged in, typically only the right light will light up, and sometimes neither light if you try to turn the headlights on too soon after starting the car. What i said above is with the car off and not trying to start yet.
NOW! to the real question. What is everybody running for voltage in the summertime? I have tried putting a set of jumper cables from my alternator straight to the battery and my DIC wont go any higher than 13.2. The other day I had my a/c on full blast, it was hot out, i was in traffic, i had my running lights and fog lights on (non-HID) and my wipers going on intermittent, and my DIC would fluctuate between 12.7 and 13.2. After I got home, i shut off all the accessories and at that point put the jumper cables on from alternator to battery to see if it was the wire jumping to the starter, and had no luck with voltage improving. Once the car cooled down, start back up, charging goes back up to around 14.1 on the DIC.

I have upgraded grounds when i bought the car (4 ga) from the battery to the ground location below it, and also another one to the engine block like below plug 8 trying to fix a different problem.

Ideas? Alternator almost toast? I just took it apart and painted it flat black

 

An update to this, I just checked this morning after starting the car...The DIC is wayyyy off. DIC said 13.7 and I went and grabbed a meter and put it on the battery and it was at 14.7. I know the 14.7 may sound high to some, but my battery may have been partially discharged from running low the other day.

 

I looked into this while my son took a whopping 20 minute nap yesterday. The maxi fuses while its running were sitting at 14.1 volts at the fusebox in the engine bay next to the battery. HOWEVER, the mini fuses, fuel pump and ecu fuses specifically as those were the ones i tested sit at 13.5 volts on both sides of the fuse. Being that they are seperate relays, im wondering where this .6 volt drop is coming from. I guess ill read through more schematics unless someone chimes in. I know its Memorial day weekend and everybody is probably on vaca and thats why I havent gotten responses

 

Ok, update. I feel like im talking to myself here but maybe this will help someone else. The maxi fuses in the underhood fusebox read full voltage, but they are .6 lower at the mini's. The only thing inbetween say the BCM fuse and the maxi fuse is the ignition switch. My ignition switch must be partially bad, I will have to pull it and do the ignition switch repair. Now, my 2nd question. When I had a 14.7 at the battery but 13.7 on the DIC, is there a possibility the datalink reference to the alternator is showing the 13.7 and getting the alternator to try to put out more than need be? I show on the schematic it uses power from the igntion switch to a datalink, and that goes back to the alternator possibly telling it when to adjust the charging level? I will do some more testing tomorrow if i get time....Lucky and BC, i know if youve seen my post, help me out here!

 

I think you are on the right path with regards to inspecting the ignition switch contacts. I have a concern with the painted alternator. All contact points must be bare aluminum, so if this assembly is completely painted, sand the contact points where appropriate. I also do not trust the jumper cables. I would favor a single copper stranded 10 gauge wire, when testing from the alternator to the battery.

 

I taped off the alternator completely when I painted it. the inside is not painted, nor are any of the contacts. You suggest the 10 ga over the 6 ga jumper cables even for testing purposes? The wire thats at the alternator now is alot bigger than 10, it almost looks to be around 6. I think alot of my problem is the voltage drops in the ignitions switch as far as my DIC reading being off, and I think for my headlights having issues, I think the contacts in that may have the exact same problem, as I see no relays between the switch and the actual lamp, unelss i missed a page on my schematic. Kinda scary actually...

 

My comments about the jumper cables are just about condition. I have seen few jumper cables that are not corroded, just from lying around. If yours are pristine, then rock on.

 

They're pretty new, my sis in law had a habit of leaving the lights on all the time. I suppose the dinging means nothing when kids are screaming . I'll let you knowif I get any further on this I may have to finish the boat instead...

 

Since you stated it that way, I'll just make sure we are on the same page. When I say "contact points", I'm referring to the surface area that contacts the engine block and bracket. These provide grounding for the case, and should be bare aluminum.

 

if you are getting a voltage drop at the switch you should also be able to measure a resistance there.....anything more than next to nothing would indicate arcing has occurred and you have carbon built up on the contacts, time to replace or repair. Good luck.

 

I dont think I taped off that area, so were not on the same page. But, woudlnt the threads and the head of the bolt to the bracket be a main grounding point as well? Maybe there was nasty build up on the bracket as well? I guess I would have to check the resistance to ground from the case to see what it was. I beleive the resistance check to the terminals of the switch will work, however, in another instance it is limited in being correct. As the current demands go up, so will the resistance, it may read 0 or very close to, but as the current demands go up, the amount of good contact area will limit the current flow. I just had all that stuff apart too over the winter, I knew i shoudl have just taken the switch apart. Anybody had any problems with the same problem on the headlight stalk having bad contacts? Im fairly surprised with the complexity of the c5 that there is still a standard ignition switch in it and not a bunch of engine compartment large relays. Alot faster to just replace a relay with burnt contacts, but then I guess how do you make money on parts?

 

Guess you'll just have to do what you think is best.....my suggestion stands.

 

Im taking the alternator out tonight to clean up that area of the case and the see what the mating surface of the bracket looks like as well, its quick and easy. The hardest part about it is seeing if my 5 month old son will let me out in the garage that long

 

That's a good problem to have...

 

Ok, i was spared some time, hes sleeping. Took the alternator out and cleaned everything up. All mating edges which yes had black paint on them. I took my straight file and filed all 4 mounting points. I then filed the corresponding bracket points, all 4, well technically 2 and 2 bronze bushings. I did not disconnect the battery as i did not want to lose any settings, and there is a large rubber boot so i shoved the power ring terminal far inside and set it by the air tube. Started the car. 13.7 on the DIC, 14.71 at the alternator and 14.47 on the battery. Kind of a strike out there. Not quite sure about the .3 volt drop between alternator and battery. 0 ohms resistance on the cable from the alternator to the battery cable. I dont really feel like tearing my dash apart tonight as I may drive the car tomorrow. This really starting to point towards the ignition switch?

 

Like I said before, I think you are on the right path, with regards to investigating the ignition switch. I just didn't want you to have an additional issue with the alternator body being painted at the contact points. If you are concerned about the drop from the alternator to the battery, you can do the jumper cable thing, and they should read the same. Would not hurt to inspect the connection at the starter....just to cover the bases.

 

Well, hmmm maybe ill pull the ignition switch tonight. I need to finsih putting the interior in the boat, but I cant go boating for another month (supposedly you cant put sunscreen on until infants are 6 months) but the LT1 wants to run too I will keep you posted. Lucky, how far are you from Madison, WI? Or at least to the state line? Do you guys down there have any kind of meets if you are in northern IL? There was a Madison area Vette club but I havent seen them meet since about the time I bought mine.

 

I'm about 2 hours from Madison. There is a cruise night everyday of the week around here....literally 7 days.

 

Maybe some day ill have to come down and check it out down there if there is that much goiing on. I live in a college town, which is basically good for driving around looking at the scenery Alot better before school lets out. Well, back to the subject. Switch is out, i tested it prior to me taking it apart, i have 0 ohms on all of the ignition lines, I didnt test accessory (brown) because i simply forgot. Not sure if I will get to pull it apart yet tonight. But I was really hoping to see something like 40 ohms or something high so when i get inside i wont be disappointed. Time will tell...

 

I think you will be very surprised at the improvement you will see after you clean and service that ignition switch. Give that a try. Make sure that you re arc the contact arms to provide more spring pressure on the contacts!!



BC