I have a 70 GS that the tail lights and headlights dont work. I have checked all the obvious stuff like fuses and light bulbs. The wire harnesses were in very good condition....a few of the shorter ones were new. I am stumped. When you open the door, the courtesy lights work, but no other lights do. Please help Rob :rant:
no lights Rob, you didn't say if you'd checked power to the light switch behind the dash, but I'd check the fuse links (there's 2 of 'em) that run up from the starter. One of them may be broken/worn thru/cracked. A busted circuit here will cause this problem; it's the first thing I'd check, before replacing the headlight switch.
reply Dave, Im not sure what you mean by that...can you explain more... Also my switch is broken where the crappy plastic bezel holds it in the dash.....I dont think there is any other wires from the switch other than the harness.... rob
no lights OK; I'll presume that the round bezel that screws into the light switch from the front of the dash is broken/stripped, but that shouldn't cause any electrical problems. There's a connector that plugs into the light switch behind the plastic bezel. There is several 'prongs' on this connector, one of them will (or should) be carrying power from the forward harness for the headlights. If you hook up a test light (grounding it out to a metal part under the dash) touching one of these 'prongs' should 'light' the test light. If this occurs, replace the light switch, it's defective. Make sure you disconnect the battery before replacing the light switch! If there's no power at the switch, there's a break in the circuit; this is usually caused by a broken fuse link (again, 1 of the 2) that come up from the starter. (it's possible the circuit could be the result of the wire(s) being broken somewhere else, firewall connector, etc. but I'd check the easy stuff first!) There is power to headlight switch at all times; the knob opens and closes the this circuit. This is why a failed fuse link shuts down headlights...no power is coming back up thru the harness. I forgot to mention in last post that the dimmer switch (on the floor) could also be defective, but I don't think this would affect your tailights. Check it with the test light to see it has power reaching it as well. Good luck!
reply dave.... you are right about that plastic bezel. Also there are a few black wires haging down that I think are ground wires from a few locations. I will test the prongs on the harness that plug into the switch and get back to you on that. I have a tilton super starter, and the engine wiring harness is brand new from M & M electrical. I dont remember any fusable links going from the starter. I just checked the fuse panel under the dash. There is a fused pink wire by the voltage regulator on the firewall that has a brand new fuse in it. Other than tahat I dont know. I can try to get some pics of my setup if you think that it will help. Also the interior lights dont work. Im assuming that thats part of the same problem, but why would the courtessy lights work ( the lights that illluminate when you open the door)? I redid my dash with all autometer gauges and am ready to tie the white wires in so that they light up, and i was told the best place to do this is the cigarette lighter wire, but that light doesnt work. Please keep all the good advice coming....... ROb
no lights The 'fuse links' I'm referring to running up from the starter are not 'fuses', per se; (although they can be) but a smaller gauge of wire than the rest of the circuit. To put it another way, the 'fuse links' are thinner wires (and consequently won't carry as much current) than the wires they join into, in this case; to and from the starter solenoid. The idea here is to protect the rest of the circuit from a sudden surge in voltage for whatever reason; because the thinner gauge wiring -or 'fusible link'- placed between the starter solenoid and the main engine wiring harness could not handle the sudden increase in current, it would 'burn out' and stop any further damage at that point. Sorry I wasn't clearer on this point earlier, the first time this happened to me I got so frustrated that I finally wired the headlights direct off the battery and opened (and closed) the hood to disconnect 'em everytime I parked the car...couldn't find a fuse anywhere in the forward harness, so I know what you're going thru! Anyway, here's what I would do: 1) Check all the ground wires from the headlights to the rad support, make sure they're tight and against the metal. 2) As you state your tailights aren't working, repeat this procedure in the trunk. 3)I should have stated both of the above much earlier! To be sure of a good ground, you can scrape a tiny area of paint away so the washer contacts 'metal to metal'. Thick paint/undercoating can prevent a circuit from grounding. 4) I'm assuming all 4 headlights are in working order and good bulbs in the tailights-if you have any doubts, ground 'em and power them up direct 5) with the battery still connected, Pull headlight switch in dash all the way out (lights on) and remove the low beam (outboard) headlight plug from the back of the light and insert test light (TL)...if the TL 'lights', repeat step 1, and/or replace headlight. If the test light doesn't 'light', there's no power in the circuit. Repeat this procedure in the trunk with the tailights. 6) As in the previous post; check for power at the headlight switch behind the dash: if the TL lights, there's power in the circuit and the headlight switch is defective and needs to be replaced. Again, disconnect battery before replacing switch! Make sure the 'ground ring' between the switch and dash bezel is seated securely. Then check hi-beam switch on the floor for power supply and good ground. 7) TL does not light...get out your coveralls...probably...I'm a little unsure (actually, a lot unsure) of what all those wires you describe hanging down are...let's hope someone had a stereo in this thing at one time...jack up front of the car, block it or put it on axle stands. DISCONNECT positive lead from battery and get a trouble light. 8) Running down to the starter solenoid (on top of the starter) from the engine wiring harness (which runs along the top of the oil pan) will be a group of wires-one of these wires splits into two smaller wires before joining (in tandem) the attachment post on the solenoid- these are the 'fusible links' or fuse links, and probably (lets say hopefully since you may have come this far :af: ) one of them will be broken, burned thru, or otherwise trashed. About 5" long, they can be bought at any auto supply store or you can make your own out of a similiar gauge wire and then reinstall them. Reconnect battery. 9) If you now have headlights, all this work will seem to have been worth it... If not :ball: start checking back thru the engine harness to the firewall plug for broken wires o No: Sorry to write a novel about this, but hope it helps; I've been there!
Here's a picture of the fusible links(red) near the starter. Make sure the knob on the headlight switch isn't rotated all the way left(dimmer function) You'll have no dash lights.
I has a similar problem once. I think that the ground wire to the headlight switch fell of when I was messing around under there. It is a single black wire. The courtesy are not routed through the headlight switch all other lights are except the , trunk, glovebox, ashtray and underhood. That is the way it looks to me. Keith
reply Ok...I feel very stupid.....but, after reading dave's post I checked, and sure enough, I forgot to ground the taillights ou: .....but im glad I had this problem because I really learned a lot!!!!!! Now, my taillights and brake lights work. My back up lights do not, and my directionals do not either. Also my dash lights work now, but the ashtray light does not. I dont care about that, but the problem is that I have replaced all of my gauges with autometer gauges, and have 8 white wires, for the bulbs in the back of them that I have to connect somewhere. Larry I think it was you that suggested that I connect them to the ashtray light wire....that wire seems really light gauge to connect to 8 other wires.....does anyone have another idea of where to tap into to light up my gauge lights....since I am not using the stock gauge lights I was thinking of using them, but Id rather not hack the harness....any ideas? Also since I have a complete custom dashpanel, I was thinking of replacing that total piece of crap ( headlight dimmer switch ) with several switches, but i have no idea what wires do what going into the back of the headlight switch. o No: I will attatch a few pics to explain what Im talking about, but thanks a million for all of your help guys... :beer
Rob, as per Kieth's post you might want to check your headlight switch ground (the round steel ring) that slides over the switch and and 'grounds' the assembly against the back of the dash. The way that switch is hangin' around, it probably isn't grounded...good to hear your're making progress!
reply Well here is where Im at.... Brake lights and tail lights work. Head lights work. :beer No directionals :rant: o No: Also, I have seen that painless wiring makes a switch that replaced that really poor headlight switch that came with these cars, but it's $50. :moonu: What I was thinking is that if I knew what wires controled what going into the dimmer switch, I could make a custom panel. Maybe a rocker switch to turn on and turn off the headlights and interior lights and a dial to adjust the dimmer. Does anyone know what wires control what? o No: Also is that mushroom looking relay under the dash the relay for the directionals? if everything else works with the lights, does it seem that the relay would be the problem? please keep the advice coming rob :3gears:
Don't spend the extra $$$$ for no reason. Stock set-up works fine. No directionals, indicate some or all of the bulbs with dual filaments, 1157, have bad/burned filament(s). Also, check your rear sockets for corrosion. You can remove the harness from the rear bumper and clean out any corrosion and then hook it back up inside the trunk to check for proper operation before reinstallation in the bumper. The rear sockets/t-lites are notorious for capturing water. I have tried many "fixes" such as new seals/gaskets, w-strip sealer, etc. Easiest and quickest fix I found was to drill a small 1/8" hole in front of each socket to let the water drain out. Never hard a problem since!
reply George, The bulbs are new, I put them in on tuesday. Also the connectors look real good, I dont know if its stock or not, but somone filled the sockets with grease ( I can only assume to displace moisture). The taillights and brake lights work, just no directionals and backup lights. I was told however that becuase I didnt install that positive neutral lockout thing, thats why my back up lights dont work. I dont really care about that, but I have to have directionals.....the cops get mad enough with my 3.5in sideswept flowmasters...I dont need any more attention. :af: Is there any ideas about solving the broken plastic ring for the headlight switch? Its just going to keep braking, I have no idea why the hell buick made that part out of plastic to begin with. I tried finding or making a metal sleeve to replace that part thinking that I could make one small advancement for man(that drives a buick)kind, but no luck yet. Also, if there are no better ideas, I am going to tap into the stock gauge light wire to light my autometers. Id rather not, but I have looked and I cant find a better idea, and nobody here seems to have any ideas. o No: ou: Please keep the ideas coming.......you guys are the best!!!!!!!!!!!! :beer Robert
Check your front lights since those are dual filament also, 1157. The plastic headlight retainer/escructheon is cheap plastic I agree but will work provided you gently pull and push the headlight slider in and out. You can run a wire tap-in to your clock lights or ac controller lights.
reply George, yup 1157's are whats in there, what else do you suggest? Is the clock wire a light on the end of a wire like the rest of the instrument lights? Is there anyway arouns using a tap? It sounds like there is not. I tried tracing all the light wires to tap directly into their source, but I couldnt tell. I imagine that I could somehow tap into the light switch itself, seeing the fact that thats the control source. Please let me know your thoughts...
Ok, well last item is the turn signal mechanism itself. Maybe someone forgot to reinstall the turn signal contacts in the column when it was apart. Also, check the harmonica connector to make sure it is properly plugged in.
