hemidann

I would appreciate some assistance in tracking down an electrical issue with my 2000 Vette, when I turn on the turn signals or e flasher all the lights dim in unison, I didn't notice this until my ABS quit working and then I could see the ABS lights dimming in unison to the flasher it is more obvious when the headlights are on, I have checked inspected and cleaned every single ground on the car including taking apart the splice packs and checking them and am pretty certain all grounds are good, the e flasher was installed new when I purchased the car due to no brake or turn signals so I don't believe its the e flasher, where should I go from here I don't want to start installing new parts in hopes something gets fixed any advice would be great, the battery and alternator are new as well. Its possible I've had this problem all along since I haven't driven the car at night I just didn't notice, it seems odd that this problem and the ABS happened at the same time, there are no LED's anywhere. This seems to be a ground problem but I'm stumped, probably be something stupid simple and it hasn't been a problem that left me stranded but I'm afraid to trust it too far from the home port, the only codes are C1255 which will not clear due to ABS not working and LDCM history but not current. The replacement is the correct GM alternator and shows no code. All the grounds were actually perfectly clean but I still inspected all pins and cleaned and used contact washers then sprayed with terminal protector.

C5 Diag

If you have a wiring diagram and know where the ground is for that circuit no need to check EVERY ground…the ground for hazards is at the left kick panel…was this one checked ??…black and white OE wiring also below.

hemidann

Yes done this one twice just to make sure, it’s not easy to get at that 10mm bolt even tested the back of the backside of the pins to ground all good, I remember now that none of this had happened until right after I did the LMC5 install not sure why that would have changed unless maybe didn’t get something plugged in good enough going back there next there is also a splice pack up under and on the right side of the dash SP208 I think. Thanks for the reply tho
i do now have all wiring diagrams for the car

C5 Diag

That would be Pin K on the splice pack…how exactly did you check it ????

hemidann

I have taken that splice pack at the kick panel off twice thinking maybe I missed something so the second time I also used a contact washer, with the splice pack bolted to the kick panel I use my ohm meter and test from the back of the pack where the wires and female pins go into the plug to ground just in case the pin itself is broken or not making contact for some reason and they all ohmed out 0 but that doesn't mean that the wire from the plug to the switch is good, all grounds I have checked so far have been clean and no corrosion or discoloration at all I pull the end cover (male end) of all the packs to make sure the inside of the female side was closed up so that when the male pin was inserted it made contact with the female pin, I found this was an issue on the left door plugs just inside the left hand door piller due to a LDCM issue when I first got the car windows wouldn't work I made those repairs as well as found a broken wire and repaired that as well, I still have a LDCM code that will not clear but shows history not current and the passenger side remote mirror does not work something about +5 volt not sure what that is but not concerned with that mirror at this time, I cant drive at night due to all my lights dimming to the flashers (just barely noticeable but I do) plus I don't like things if they are not right if I can possibly help it, I was the lead mechanic and teacher at the last company I worked for for 15 years as well has having my own shop for 19 years and 5 years at a Corvette/Muscle car restoration shop for 5 years and this little issue is driving me crazy, maybe the best thing to do is go fishing for a couple of days and forget about it. I'll be will to bet money it will end up being something really really simple, sometimes you just get too focused on something and can't see what's right in front of your face so others input helps break the spell. Sorry its so long but just getting all info

C5 Diag

Using an ohmeter to check grounds is not the best way to do it…find yourself an old headlight bulb (pic below) and hook one end up to B+ and then probe the ground your checking…if ground is good the bulb will be bright…I use different bulbs depending on how many amps is on that circuit…something like a fuel pump I’ll use an old high beam or a few smaller bulbs in series.

hemidann

Ok so now I am embarrassed I knew that and why it escaped me escapes me. I'm going to use heat exhaustion as my excuse, I guess too much focus is a bad thing sometimes, thanks for breaking me out of it.

C5 Diag

I wouldn’t feel bad !!…even the GM Engineers needed some schooling too as you can see in this diagnostic “tree”…check using resistance !!

Got uid0

Hate to ask but how old is the battery and water levels in this texas heat. Any checks on alternator output and battery with load? Sounds like a bad battery cell or alternator to me.

hemidann

Ok so I have without a doubt checked all grounds are good, the battery is 2 months old and I have load tested as well as O Reilly Auto tested, also tested the alternator as well as O Reilly's tested, all good, I remember putting new aftermarket visors on that were LED so I removed them no change, installed a new flasher today, no change, radio removed as well as A/C to remove anything electrical from the system that can cause an issue, both doors have been unplugged, when the e flasher or turn signal is engaged all lights dim in unison to the flasher, its not like strobe light flashing but noticeable slight dimming. Where from here, I have a feeling its in the instrument cluster so I guess its next, any other ideas are welcome.

Got uid0

I had an issue on a c5 where it was the Head Lamp switch assembly https://www.rockauto.com/en/catalog/...mp+switch,4472

Had to force it to high beams low beams off on high beams before the low beam would work. You can temporarily repair it by taking ti apart and cleaning bending the contacts but it wont stay fixed if this is the culprit. Common failure on c5's tho if you search.

PlanoLeMans

Ok the reason the lights dim is that the voltage drop across the light decreased. So we need to understand why this is happening. Do you have scope capability with your scan tool? If not you maybe able to see this with a fast enough dvm. Let start with the battery and then move to the signal lights. You are trying to find where the voltage drop is. Ideally the drop across the two terminal of the light should be that across the battery. If not measure from + battery terminal to + terminal of the light to see if there is a voltage drop. Repeat across - terminal of light to ground, and ground point to negative battery. For the path you find the voltage drop, repeatedly making the path smaller and smaller, using the wiring diagram, until you find the point causing the drop and fix it.
The first step is to see if the voltage drop across your battery follow your flasher. Is there a difference with or without the turn signal on.... you are trying to start with isolating the circuit before you begin isolating the paths in the circuit.