My generator light has stopped working on my 1970 GS. It worked every time I would turn the ignition on until just recently and now it won't come on at all. My emergency brake warning light was also out, but I got it working. I removed the light socket for the generator light and bench tested it and it lit up just fine. Any ideas?
There is a fuse for gauges, right side of fuse block, last fuse on bottom. First step, check the fuse.
My 70 Buick Chassis manual says could be a shorted positive diode, or an open in the light circuit. Got another alternator?
I'm gonna get one to hook up and see if the light comes back on. ---------- Post added at 06:26 AM ---------- Previous post was at 05:18 AM ---------- How can I find if there is an open in the light circuit? Where should I check and what should I check?
The back of the instrument cluster has a sort of printed circuit board on it. There is a plug that engages several pins that power that whole cluster. I can't tell you exactly what's wrong, it could be several things. To get to the wiring requires pulling the instrument panel. This article will help with that. http://www.buickperformanceclub.com/cluster.htm Look for something obvious like a broken pin or damaged or loose hanging wire. Make sure all the gounds are intact. Before I did any of that though, I would see if it is the alternator. You really should have a copy of the 70 Buick Chassis Manual. It really should be the second thing you buy after getting one of these cars. They are available used (on E Bay), reproduction, and even on CD ROM. You need a copy to do any trouble shooting of these cars, especially electrical issues.
I tried a different alternator and a voltage regulator. Made no difference so I'm assuming it's in the instrument cluster itself. I've got the chassis manual. It has wiring diagrams that are helpful, but it doesn't really go into detail on this issue since it makes broad statements that a novice like myself can't get a lot from like "there's an open in the circuit". That link looks like it will be very helpful though.
I can't remember for sure but are these bulbs like the marker light bulbs that push in and 1/2 turn? Do they not ground to a dash circuit when plugged in? Just thinking maybe something as simple as a bad contact in the dash o No:
It's a 194 bulb that pushes into the socket. The socket goes in the back of the gauge case and locks in after about 1/2 turn. It has two metal contacts on it one on each side of the bulb that come into contact with the circuit board on the back of the gauge when it is locked in. It very well and most likely is a ground (there's an open in the circuit), but I'm not sure where the grounds are located. I'm thinking I might be able run a separate ground to the case and maybe make it work??? I dunno. Another interesting observation is that when I pull the light switch to turn on the headlights the temperature gauge in the same case goes from C all the way to H.
Humm, that's a weird one, is it possible that a wire somewhere got pinched? Have you been under there doing other work that may have disturbed the wiring? Seems funky that this kinda thing would happen all of the sudden. What about try plugging the bulb and wiggling in and out a few times to make a better possible contact.........of course while the ignition key is on :grin:
Ok...my questions would be, is the car running now? Was it running before, or are you just working on it? Did you do ANYTHING at all between the time the light worked and stopped working? Like were you fishing around up under the dash with wires, or did you drop the column? Messed with the ig switch at all? I'm thinking ground, there are many on the dash. One to headlight switch, 1 to wiper switch, 1 halfway down the steering column, and more. I've heard of lights staying on before, off is not common. It's easy to be messing behind the dash and pull any of those grounds off, because you can't see them. Like you reach up to take the gen bulb out, and you can knock something else off.
The car runs I started it today to make sure. I'm working on it and in the process of replacing the clock so it's very possible I've knocked something loose fiddling inside the dash. I've dropped the column to get better access to everything. Another thing is that the backlights for the clock will only work if I run a separate ground to the case. They worked fine before with the broken clock with no extra ground needed. I haven't messed with the iginition switch this time, but have in the past. When I did before it made no difference. Everything still worked so I don't think that is the issue but anything is possible I guess. ---------- Post added at 07:22 PM ---------- Previous post was at 07:20 PM ---------- I'm doing some work see post above. I've tried all kinds of wiggling. It worked for the emergency brake light but no luck with the generator light.
Check the ground that's about 1/2 way down the column on the lt side. Just from memory, I think it's on the big pedal support bracket. There should be a black wire clipped on there. I would also get a jumper wire and ground the gas gauge pod and see what happens.
The temp gauge going the H when you pull the light switch is a sign that the temp gauge is grounding through the light switch. The ground on that gauge cluster is suspect. The GEN light ground is connected directly to the Temp gauge ground on the little circuit board on the back of the gauge cluster. This goes to the brown wire which goes back to the brown on the voltage regulator. You may then have an open in the circuit board at that point. I am looking at the 1971 service manual page 120-60.
Pulling the lights on with the ign switch off makes the temp gauge go to H. If you then turn the ign switch on, it goes back to C. Not sure if that is normal operation or if it's not how to fix that outside of maybe replacing the gauge case or running a separate ground maybe?? I've checked all the wiring and it is good and connected. As a last ditch effort (I don't know why I didn't do this before) I tapped on the lens and the gen light came on. I've tried it many times since and it comes on each time the ign switch is turned on. I guess I was too focused on everything inside the dash and on the back side of the gauge to think to try that before. Anyway it works for now and thanks for all the help here.
Of, course. lol Beside the Buick Chassis manual, what other literature/info sources would you recommend I get? (I have a '71 GS 350 convert) Thanks
I have always found the chassis manual to be the most important, the one I refer to the most. If you want the Fisher Body manual or the Assembly manual, they are valuable as well for information.
