Ok, so the contacts were badly burnt...amazed they had 0 ohms...wtf. Its cleaned and im about to pop this switch back together, but I think if i start my car right now my wife would KILL me. B&B bullets plus nighttime for the kids, yeah, not good. I probably wont get to start the car until tomorrow night as I leave for work at 6:30am.

 

I said screw it and went and threw it in. Key definetely feels different starting it up...its tighter. So, crank her up, 13.9 on the DIC, and 14.52 at the battery, sigh. The fuse for the fuel pump was at 14.19 volts, so at least were getting closer!!

 

The wire run into the car and back out to fuses will never read the same voltage as the wire coming from the alternator. Every wire and every connection has some resistance and some voltage drop.

The best would be to make sure you have good wiring from the alternator to the battery and then power the HID's via a relay from the battery. Part of the common cheap HID kit installation is replacing the 10A headlight fuses with 20A fuses so that by itself is an immediate indicator that the HID's overload the headlight circuit.

I put in Euro headlights with 90W/100W bulbs and relays and they certainly light up the road. Some day, I might try good quality bulbs to see what the difference is. I got a H4 HID kit with the headlights but the beam pattern of HID's in a Halogen housing always suck and blind all the oncoming cars.

Peter

 

Don't get distracted by the disparity between the DIC and actual reading at the battery. Now that you have repaired the ignition switch, you can move on the the lights.

 

I have yet to swap any fuses for the headlights. I considered relay isolating my headlights, but id rather not have un-necessary wiring cluttering things up, I would rather just fix the problem. Yes I understand there will be a voltage drop between all wiring and connectors, but the drop im getting is very large in my opinion. You shouldnt have 14.7 at the alternator and 14.45 or whatever it was at the battery. I will be checking my connections at the starter first, as it may not be the wire thats bad to the starter, it may be from the starter to the battery that is partially bad. There should never be a voltage drop of over a 1/2 volt in a matter of a few feet. There is either a few relays that have bad contacts inside, or some wires that have seen better days. The fuel pump relay is new as I had a problem with that 2 years ago, and i think that is why my fuel pump output is higher than the rest. I will dig deeper and do the same repair on the headlight switch and take some photos to see what the contacts look like on that.

 

BTW, is there any way to correct what the DIC says? I just worry about the other day when it was dipping down into the mid 12's, it had me fairly worried.

 

well to anybody that has been watching this I have come to a conclusion. I have not fixed the gauge cluster/DIC voltage differentation to the battery and it is unlikely I will have the time to investiage that portion of it. But after following some threads on here, it seemed as if the symtoms I am having with my headlights are much different than the other users on the board. Some in this post have stated I am drawing too much current and recommend to replace fuses, while others recommend to relay isolate my headlights. While both of those may work, has anybody ever just taken their car to have the battery load tested? I checked my battery voltage today and it was at 12.05. I dropped the lower dash panel and checked the red feed wire for the headlight circuit, it was at 12.00. I checked the white wire which is the feed for the headlight switch and i was at 12.00 So the relay inbetween the headlight switch and the battery is not my culprit, im guessing this relay will allow the bcm to turn off the headlights if needed. I turn on my headlights and i get 11.65, which was not enough voltage to fire the HIDs, i believe the voltage dropped to this due to the tail/parking/sidemarker lights being on along with all interior bulbs. I then checked the red feed wire to be sure, and it was at 11.70 so .05 drop between all of this. I will find out tomorrow if the battery is junk. It was the "premium" at the local farm and fleet, and conveniently it has a 36 month free replacment and the sticker on the side is 3/07. F me.

I will keep all posted as hopefully this will help someone.

 

Okay, speaking as an electrical engineer here, I have to tell you that to fix the problem, you HAVE to put in the relays. Doing anything else is the actual jerry rigging, as the headlight circuit on these vehicles was just not designed to power headlights that pull that much juice.

If anyone says you have to increase the size of a fuse or circuit breaker on ANYTHING, and you don't also increase the gauge of ALL associated wiring, that person is setting you up for a fire or at least a low power condition in the future. Installing the relays and running your HIDs straight from the battery is the only *correct* solution.

 

True. The reality is, the current spike is only on start up (especially with the cheaper ballasts). The more expensive ballasts only have a start up current draw of 6-8 amps, while the cheaper ones are up to 15 amps on start up. Since you are an electrical engineer, I'm sure you know the ballast current draw drops off quickly after start up, and stabilizes, which falls well within the current capacity of the circuit.....and why there are not droves of burned up C5s.

 

First off you're chasing problems that aren't real. Isn't a car on the road that reads the same voltage at all locations. Sunday I spent 5 hours trying to figure out why my Vette decided not to start saturday. My main two diagnostic tools were a fluke meter and a test light. The fluke had me running in circles from the various voltages I was reading. For the record the problem turned out to be a bad battery ground terminal inside the battery. The battery has top posts and side posts which complicated my search because the top posts were reading correct while the side terminals were flaky. After the new Optima the voltage on the dic is 14.02 but the fluke is reading 13.98 at the battery.

Anyways as far as your problem I'm going to guess that changing the fuse will do nothing and adding the relay harness will also not solve the problem. Why? Been there, done that. What solved it was another set of better quality HID's. I did cure a flutter I developed by cleaning the grounds and headlight connectors. That may or may not be your case. Bad grounds will also affect your voltage readings as well.

Good luck and try not to over think these electrical problems.

 

So you claim that these may be cheaper HID's, however, i can put them in my wife's CRX and they light up without the car even being turned on? Im with Lucky on this one, and I understand you are an electrical engineer, they draw major current on startup, which is why only one will light up without the car running. Why is this? most likely because there is also alot of juice being used to power the headlight motors and taillights, etc. I guess I have never seen an actual comparison on different brands of HID's and what their startup vs running currents are, but once again, a 90 Honda can light them without the car running but a c5 cant? And also, How would determining the voltage that is going to the headlights and figuring out a current issue to run HID's and trying to fix/isolate a problem be Jerry rigging? I understand the relay bypass harness' work, which is what I intend to do as it appears to be the last option, as then it will not be such a strain on everything else, but if you ask most anybody, they would consider that jerry rigging.

 

I have checked and cleaned all grounds on the car, and added 2 4 ga grounds as seen in the first post. Even after all of this, im still getting a voltage reading that is far off from the battery. It will take more time reading through schematics and testing, I was tired and groggy last night looking at schematics, but it appears there is a BCM relay, which would feed the cluster, and if there are burnt contacts in that relay, it will cause the voltage drop in which the cluster reads as well...

 

It's like I posted before. All the wiring and connections and switches have resistance. You have a circuit which runs around under the hood into the interior and through the light switch and then back out to the lights. You install these HID ballasts that have a high current draw when they are turned on and that higher current draw will cause a higher voltage drop when first turned on.

The relay harness will connect the ballasts directly to the battery which will provide lots of power without the voltage drop the stock harness has.

My lights will draw about 14A (100W = about 7A each) on high beams. I ran relays and 12 gauge wire. I could have just used the stock wiring since I believe it has 10A fuse for each headlight. But, the relays will keep the headlight switch from failing and do better to provide 14V to the headlights which keeps them brighter. The wiring harness is neatly done so I don't see how it is a hack.

You can try using a quality meter with a high/low recording to capture the voltage dip. If that's not quick enough then a scope is required.

Chasing something like the cluster power relay will not fix your headlgiht problem. But then, I don't know if you're trying to fix the headlight problem or your DIC reading anymore.

Peter

 

Well, the headlight thing im thinking may be an actual bad battery..I still have yet to take it in. The headlights work totally fine once the car has been running for at least 10 seconds. The voltages all match everywhere within a few tenths of a volt so there is no major drop anywhere. If the battery is bad and cannot keep a stable voltage, i checked it last night and it is at 11.9 which is not very cool IMO. If when starting, and it dips to say 10.5, and you try to turn on the headlights, the voltage is lower in which the current draw will go up and really not allow the headlights to light up. I am not arguing your point of relay isolating the headlights, id just rather not have to do that, but apparently with HID's it would be required on a c5. I guess I am just surprised that a car that is as equiped with electronics, relays, bcm's, etc as the c5, doesnt have external relays for everything. Like any new GM, you look at the back of the ignition switch and everything is like a 18-20 ga wire, and external relays for all ignition components. I would guess that would be the end of failing ignition switches. Same with the headlights. I have to get my battery load tested and/or replaced if found to be bad. The DIC is a whole differnet ball game, i was just throwing it in there to see if anybody had recommendations while we were going through the ignition switch and what not. I have been actually busy at work for once surprsingly so i cannot sit and read schematics online all day to see what needs to be tested.

 

Man I wish I had your problem of 12.7v and 13.2 etc. etc. I been running about 11.8 and sometimes down to 11.2 volts on the DIC and on the head unit of my JVC, aftermarket unit with a voltage meter display, which shows about 12.2. My battery is in good shape, had it tested and had alternator checked. If alternator is putting out 13 plus volts to your battery then alternator should be fine. Battery should sit with no connection to car at about 12.3 or there abouts. My next step is to go through the ground connections like Bill Curlee had in his sticky post on the front page of the forum. Hope you get yours solved.

 

You would have to read the beginning of the post, all that has been done. Your JVC is getting its voltage reading straight from the lines powering it. I would do the ignition switch cleanup which is in 10 million other posts, as mine proved to be pretty darn burnt. I know the other guys are smarter than me, but im not dummy when it comes to electrical schematics, etc. There has to be a logical reason why the DIC cannot read nearly close, and hopefully I have the time and ambition to find out why. There has to be something with the relay that feeds the PCM and the DIC, etc.

 

Well, I'm no expert with schematics either, but I sure do not see any relay feeding the IPC.

 

Run a single 10 ga wire from the positive battery terminal to the BATT terminal on the back of the alternator (under the black boot) If the alternator is capable of charging the battery, that will prove it. If you resolve your issue, you have a bad connection at the starter.

Find the fuse/s for the IPC. Measure the voltage at those fuses to ground with the key ON engine running. Each fuse MUST be reading full battery voltage. Theres NO relay for the IPC.

Bill

 

Exactly. It's basically a parallel circuit, with the exceptions in series being maxifuse #47(IGN 1), minifuse #19(IPC), and the ignition switch. Like Bill said, theoretically, the voltage measured across any of the parallel legs should be battery voltage. If you are experiencing a voltage drop, then you need to start at the closest leg to source voltage, and work your way toward the ignition switch.

 

Thanks for the info. I did do that when I came across the post quite some time ago. And I did find the contacts in need of sanding as they were pretty bad. But you make me think that maybe I should look again at the ignition contacts. I am watching this post and the progress here pretty close. Hope we all find out what is going on. I agree with you. Why can't the DIC read the same as other test points given maybe 2 to 4 tenths off for a crummy connection, etc. Thanks again.