Lou99Vette

I added a post to the "IMPORTANT ELECTRICAL INFORMATION (Long!)" sticky thread since there was another user with the same exact problems. But it seems that thread really isn't for troubleshooting. So I figured I'd post my own thread with hope of getting some feedback.

Here's the quote from C5Joe559 and my initial reply from the other thread:

I have this exact same problem. Does anyone have any ideas on what it could be? It happened the day after a lot of rain, so I suspect something is wet somewhere... but cant find it.

Here's a list of the following things I did so far:
1) checked both connectors on each door. The ones that go through the accordion tubes. No wetness. No lose pins. Made all the female contacts tighter for the hell of it, cleaned and put dielectric grease on them.

2) checked BCM. Took it apart, checked PCB for wetness or build up. Cleaned all the connectors that plug into the BCM. Put dielectric grease on them.

3) checked battery terminals.

4) baked out the interior with the heat at max temp for over an hour with windows closed.

5) cleared all codes. took it for a ride. Only codes that return are B2578 and B2583 (front turn signal relays).

6) checked the individual relays. both work fine.

6a) If only #40 is unplugged (front left), the interior dash lights stop pulsing, and only one directional light lights (instead of both at once). If parking lights are on, only that directional light on the dash will be solidly lit.

6b) if only #38 is unplugged (front right), the interior dash pulse, both directionals on dash light up. Both front directionals turn on.If parking lights are on, both directional lights on the dash will be solidly lit.

Rear turning signals always work as they should.

Lou99Vette

Troubleshooting day 2:

well I followed the service manual troubleshooting steps for the B2578 and B2583 codes, and everything checks out until I get to step 9 which wants you to check for "voltage shorts" at those relay connections. Not sure what if it means shorts to ground or to 12V, but I checked for ground shorts.

I get shorts to ground on CKT 1314 and 1315, which go to the front turning lamps.... but those circuits go to the bulbs, and then to ground.. I'm not sure what kind of resistance the bulbs should have.

I also get shorts to ground (continuity on my DVM) for CKT 14 & 15, which go to the turn signal switches, and the hazard switch. So the short could be in either. I believe the hazard also contains the flasher as well.. so that is a good chance where my problem might be.

when both relays #38 and #40 are taken out, everything works perfectly. No pulsing dash lights, no constant clicking relays, I can arm my alarm with the fob. So the problem has to be either of the above mentioned things, or from the BCM (since it appears to control the relays going on and off by switching ground to them).

Anyone have any experience with these exact problems and can give me a clue on the best thing to check next?

Edit: Actually looking at the schematic again it looks like I made a mistake. I should find ground on CKT 14 and 15.

Edit2: I'm pretty sure it's the multifunction switch. It's not the flasher/hazards since my back directionals work just fine. It's not the bulbs, took them all out yesterday. It's not the relays. I ordered a multifunction switch from amazon for $165... hope this is it. It's an expensive educated guess...

NVR_L8

This started happening yesterday. All my exterior bulbs are LED's. I thought this might be my problem with the low resistant's of the bulbs.

Lou99Vette

The new multifunction switch came today. Just plugged it in without taking out old one. same problems.... waste of $200.

Anyone have an clues as what the problem can be? It would be greatly appreciated!!

lespaulr0cker

Sorry the $200 guess didn't work, and I'll throw in a disclaimer that I have zero experience with this issue.

However, I do know that in the summer when it gets hot, folks start using the A/C alot in the car and condensation from the adjacent vent causes trouble with the hazard switch, which also provides functionality for the turn signals. The usual symtom is "no turn signals" and sometimes just repeatedly cycling the hazard switch can relieve the symptom, at least temporarily.

I have a 99 and had the no turn signal issue last year, replaced the hazard switch ($35?) by taking out the center console, HVAC ctrl, and radio, and having my little handed beautifull wife work with me to replace it.

Lou99Vette

At first I thought it might be the hazard switch (since the flasher is built into it), but then I read that if any of your turn signals work, that the flasher is working. I bought a generic flasher for like $4 that I'll just temporarily hook up (without hacking the harness) just to prove to myself that it isn't the flasher.

I'm hoping it's not related to the BCM since they are expensive.

lespaulr0cker

Uuuuuh...I don't think you are going to be able to use a "generic flasher", the hazard siwtch is a miniature module with circuitry inside of it.

Just get the proper part if thats what you think it is, disconnect if it first and see if the problem goes away before spending the money.

Lou99Vette

Yeah, I know it is different. There are plenty of posts by people using separate generic flashers, and bypassing the hazards switch flasher. I don't intend to do that permanently, just to as a troubleshooting test. But I don't think my problem is related to the flasher/hazard switch.

Rick Perkins

I'm having the exact same issue as you. Tonight I went out and took out both front bulbs and checked the sockets. ( I changed the drivers side socket out about 6 months ago) all seemed ok. I then pulled the two front running light relays. They were a pain to get out. There was some oxide build up on the blades. I cleaned the blades on the relays, and put them back in but i swapped positions with them. I started the car, tried both blinkers, hazard lights, headlights off and on multiple times and turned the a/c on full blast. Everything worked as it should. I'm diving it to work in the morning and we'll see what happens. I'll keep you posted.

Well I just thought I was going to drive it to work today. After the work last night, I got up this morning went out to the garage to leave and found the battery deader than a door nail. Now I'm really confused. I'm going to pull the alternator and have it checked out first. I know it had a little current draw so it may have went ahead and crapped out. I'm sort of getting the bad feeling that the bcm may be my problem....
Rick

Lou99Vette

I still haven't fixed my problem, but I haven't really had much time to do more troubleshooting.

I'm a little confused how the lights are supposed to work now that they don't work right. Does anyone care to clarify how they should work using my crude MS Paint picture?



Which lights are supposed to be the daytime running lights? B right?

B are also the turning signals I think. And A are just sidemarkers that are on when the headlights are on?

right now with the headlights off, no lights are lit under normal conditions. If I use a directional, B and A both blink (both sides), very dimly...

can someone reference my crude drawing and explain which lights are what, and under what conditions they should be doing stuff?

thanks in advance

Rick Perkins

Today I took the battery out and re-cleaned the grounds under the battery box. I found a hole in my ignition relay so I replaced it just to prevent a future problem. I took my alternator off and had it tested. It failed. (it failed at autozon and 2 different O'reilley's) I replaced my alternator and everything works fine. Blinkers work fine, running lights are fine, no more panic alarm when the doors lock, no more dash lights flickering. I had an idea there was an upcoming issue with the alternator. I had already pulled to field wire off a couple of weeks ago and checked the amp draw between the wire and the alternator housing. I was getting about 1 amp of draw and there is supposed to be none at all. Maybe your alternator is following the same path as mine..
Rick

lucky131969

What?? Which relay exactly? Post a pic...

Lou99Vette

So can anyone answer this for me? Everyone here has a corvette, most of them with non-crazy lights

johnpowe

I had the same problem on a 03 Z06. I had been slowly changing all the lights to LED's. I had installed a LED turn signal flasher when I put LED's in the rear turn signals and rear marker lights. So hyper flash was never a problem. I had also installed LED's in all inside lights except the dash lights.
The problem started as soon as I replaced the DRL's and front markers with LED's. (DRLs are the same as the front turn signals)
And I do mean it was the exact same sympthons that you experienced.
I never did find out why the problem happen.
What I did was remove the DRL LEDs and reinstalled the stock bulbs (they were brighter anyway) and that solved the problem.
During troubleshooting, anytime I reinstalled the LEDs into the DRL's the problem came back. Changing any of the other LED's did not change the problem as long as the DRLs had LEDs installed. My conclusion was that the DRL LEDs were causing the problem. I suspect that the reduced load of all the LEDs together were somehow causing the problem, and the DRL LEDs were the tipping point. The LEDs I used were set up for 12v use and had the resistors needed for 12v use. I am NOT a electrician so I do not have a good answer for why the DRLs would cause this, but then I talked to a couple of auto electricians and they didn't either. I no longer have the Z06, I now have a 01 vert and have not changed any lights to LED yet. I will eventually and I will either change the DRLs first and see if I have the same problem. If I do, I will go the same route and NOT put LEDs in the DRLs just all the other light will be LEDs. As I said the stock lights are really brighter than LEDs. I know this info isn't much help, just thought you would benefit from my experience. If you solve the mystery I would be really interested the fix. I did not try switchbacks in the DRLs and do not know if they would change/effect the problem in any way.

On the subject of the turn signal/hazard flasher. If you have LEDs for turn signals you will get hyperflash unless you change or bypass the stock flasher with a LED compatiable flasher. The easier way to do this is to buy a LED bypass flasher kit and install it in the wiring harness. You just drop the driver knee panel and install the flasher into the wiring harness. The kit will have very simple directions for doing this. It will not affect the hazards they will still work using the hazard dash switch.

98Artic

Lights "A" according to your diagram are only side-marker lights that go on when the main headlights are on. "B" has all blinker functionality and are also the daytime running lamps.

Rick Perkins

I'm curious as to what you found if anything. I thought my car was fixed but was recently proven wrong. I ordered a new blinker assembly and changed it out. No help. Still the same issue. I had a spare hazard switch so I changed it too while I was in there. No help. Unless the spare was bad. I'm wondering now if I may have an issue in my bcm.
Symptoms are: Front running lights and blinkers don't work. The rears hyperflash. The dash lights flash when the brake is pressed during the day. The hazard lights work properly when the button is pressed. If the key fob is in the passive position and I let the car lock itself the alarm goes off.
I'm not going to drive my car again until I figure this out. If you find out anything please post.
Thanks
Rick

Lou99Vette

Well I think I have isolated my problem. It seems to be in the hardness/connectors for all those lights at the front of the car. There is one big plug that plugs into a harness that runs towards the firewall of the car. It's located on the passenger side, down in the nose of the car, to the side of the head light. That harness on the opposite end splits off into a few different bundle of wires that go to the lights on both the right side and left side of the cars front bulbs.

I was wiggling all those harnesses around and the problem has gone away. I've had it go away for short periods in the past, but it usually comes back. My guess is when I hit bumps ect. So now I have to wait for it to mess up again, and try to isolate exactly which wires/connector the problem lies.

dgrant3830

Hoping for the best on your issue and looking forward to hearing if you really found it. I'm a bit concerned that you use dialectric grease on the pins of the BCM though. I'm thinking it could cause you some issues now or in the future with some of the small current items flowing through there and the serial data buss communications.

Lou99Vette

@ Rick Perkins,

I was worried it was my BCM too. But I'm pretty sure I narrowed down the problem (at least for me) to the harness that goes to all the lights in the front of the car.

If you get a chance, as a test, unplug the connector for this harness, and see if your car functions normally. It won't have front blinkers, or marker lights. And will hyper flash (since the fronts are disabled), but your dash lights should stop pulsing, and your alarm should stop going off when arming the car (it is doing that because there is a short somewhere, and it is draining current. the alarm senses that and goes off).

If unplugging that harness makes most of your problems go away, then you know the problem lies in that wiring after that plug (the connector it self, or the wires going to all the lights).

Rick Perkins

Well I think I found it. Taking a hint from Lou, I pulled the blinkers and side marker lights out the front of the car and began checking all the wires and bulbs. All were fine. I unplugged the harness behind the front bumper, pulled the plug and the splice pack out and let it hang out the front of the car. I turned the passive feature back on and walked away from the car. No alarm.. I plugged the harness back in, walked away from the car and the alarm went off again when the car locked. I unplugged the harness again and tested again and no alarm again. I then pulled the splice pack apart to check for corosion and it was clean. Just before I put it back together i noticed one of the sockets where one of the blades plug in to the splice pack was open. I took a small bladed srewdriver and closed the gap on the what I call a spade clamp. I then plugged the harness back in and low and behold everthing works as it should. Blinkers work, running lights work, no flashing dash lights and the alarm doesn't go off when the passive locks the car. I think I'm going to take this spice pack out and find a better way to connect these grounds.