The turn signal on my 1969 Cutlass lights up like a Christmas tree and blows when I switch ignition to the ON position. Brake lights, tail lamps and hazards all work, But turn signal has nothing. I checked all bulbs and they are good. I have a loose bulb in the front parking light passenger side. Bulb doesn't connect well. Moving it around works but doesn't light all the time (loose/bad connection?). Could that be the bad connection causing fuse to blow, or am I missing something? Is there a procedure for diagnosing where to look for the short? If it is the parking light socket, can I just replace with a standard socket from the automotive store?

 

Are you saying the RH (passenger) side bulb/lamp lights up like a Christmas tree when the IGN is turned to ON or both the driver and passenger side & light up when the IGN SW is turned to ON? Is the turn signal switch itself engaged (either RH or LH) when you turn the IGN to ON, or the turn signal(s) light up w/o the turn signal switched to RH or LH?

 

Does the dash panel turn signal illuminate? Since it's a turn signal - does it flash or does it not flash when it lights up and you turn the IGN SW to ON?

 

As soon as I turn the key to the ON position the fuse in the fuse panel lights up and blows. Obvioulsy a lot of current going through it. I don't even get a chance to turn the indicator on the column. The parking bulb is intermittent in the socket. If I turn the bulb in a certain position it lights up, but then I let go and it goes out. The bulb is not making a good contact. I'm wondering if that is the problem with the fuse blowing or is there something else I should check. Hazard, lights and parking lights all work, so it is not the bulbs.

 

You already know you have a bad socket as you've stated the bulb in the socket is intermittent. That socket has to be repaired and is most likely your issue shorting to ground. Yes, you can replace the socket or the entire assembly.

The wiring diagram is illustrated & found in your 1969 Chassis Service Manual or here >>> https://classicoldsmobile.com/forums...agrams-170766/

You can remove that socket &/or assembly thereby isolating that socket assembly from the signal lamp pathway. Turn the IGN SW back to ON..if the fuse does not blow, you've found the issue.

A light circuit tester is an excellent tool to troubleshoot these issues.

 

Vintage Chief,
Thanks for your advice. I unplugged the parking light wires on the bad socket from the harness and unfortunately, it still burned out the fuse when I switched igniton to ON position. I did have some wires come loose on the rear taillight harness and tried to reconnect them. I was worried that somewhere the wiring was bad so I replaced the rear light harness with a spare I had from the PO of the car he had included. The fuse still burned out. Seems unlikely both rear harnesses are bad, but possible I guess. I was wondering if there is something wrong somewhere else? Should I try disconnecting the rear tail harness from the main harness and see if the fuse blows? If it does, is there somewhere else to check?

 

Disconnect the turn signal switch, see if the fuse blows. If not, tear into the column.

If I remember correctly, the backup panels are also on the turn signal fuse.

This is where a factory service manual with a good wiring diagram would be useful.

 

If you do not own a circuit light tester, buy one ASAP. You need to be able to identify where you do/should have voltage and where you do not/should not have voltage. They are ~$10. Buy one with the sharpest point possible. It allows you to probe each wire. You need the right tool to diagnose your issue(s).

 

You have a short to ground somewhere in the turn signal circuit. Since no one on this forum is clairvoyant, there is no way for anyone to know were the problem is without tracing the circuit as Norm suggests. There is no magic here, only brute force troubleshooting. I will say that if the fuse blows with the turn signal switch in the straight ahead position, the problem is NOT your socket (that may be a different issue, but not this one). There is no power to the sockets if the switch is not activated. Open your chassis service manual to the wiring diagram and trace EVERY wire that is between the DIR SIG fuse and the switch.

 

I'll add that the DIR SIG-BACK UP fuse also powers the backup lights. Any chance THAT wire is pinched somewhere? By chance has this car been converted from a column shift to floor shift?

 

Test voltage across the fuse holder with no fuse installed - assuming the fuse which is blowing is the DIR. SIG.| BACK UP fuse (as both Matt & Joe indicated this also feeds the BACK UP lights).

With no fuse installed turn signal SW in the straight ahead position, turn the IGN SW to the ON position, using a test/circuit light measure voltage across the fuse holder with no fuse installed. Test BOTH fuse holder adapter positions separately (independently) with the car ON. You should measure 12VDC on ONLY one fuse holder adapter - not both.

 

I had a problem like this years ago. On a 70 442, kept blowing fuses. Took me a long time to find out why. I finally traced it down. I had replaced my valve cover gaskets. On the pass side was a wire, can't remember what it all hoked up to, but it did combine with the signal lights. This was a AC car, so crowded on that side, and that wire got caught under the valve cover, and cut the wire coating and I had a dead short. I have found out so many times, as I have gotten older, if you have a problem, ask your self, what was the last thing I worked on. It mat have caused the problem.

 

Harv, are you possibly thinking of the driver's side valve cover? There are no wires related to the turn signals on the passenger side of the engine. The forward lamp harness that contains those wires runs from the firewall connector under the master cylinder, along the driver side inner fender to the core support, then across the core support to the passenger side lights.

 

Guys,
Thanks for all your advice. I appreciate it. I got busy with work so paused on working on this problem. However, with rear harness (lamps, back up lights etc) disconnected and both forward harnesses going down to the front indicator lamp, the fuse still blows. So the problem must be in the main harness in the engine bay or under dash I'm thinking. No work was done to the car prior to the problem. It just seemed like they stopped working. I haven't got the testing light yet, but plan to. The turn indicator switch is in the straight ahead when the fuse blows. The car was originally a column shift and still is. As per adivce, I guess the best thing to do is trace every wire from fuse to switch in the column? Should I remove fuse panel to make sure wires are intact leading to the actual location of the fuse in the fuse box?

 

First order of business is to test both sides of the fuse holder as described in Post #11

 

Did you make sure the "loose bulb" is the correct one? I have seen many times where an 1156 bulb was installed where an 1157 should be. Externally they look the same, but the 1156 bulb only has one contact on the base and will short the parking light circuit to the turn signal circuit. This does not typically cause the fuse to blow, but that brings up something from my past. If an aftermarket stereo has been installed, the gray dash light wire for the factory radio is often used as a ground wire. Effectively shorting the parking light circuit.
First thing to do, remove the passenger side bulb and make sure it is the correct one. Make sure the contacts in the socket are still captive and not touching each other or the socket.
If you can find a small light bulb and socket with wires on it, wire it into the fuse panel. Be neat about it and pinch each end of the wire under each end of a BLOWN fuse. Now when you turn the switch on, the light bulb will light up instead of blowing another fuse. This will allow you to know when you have found the problem without sacrificing more fuses. When the light goes out, you have fixed the problem.

 

Have you tried the advice from post #7?

 

I have tested both sides of the fuseholder using a circuit/light tester as described in post #11. Only one side of the fuse lit up the light, so I assume that the fuse block and wires to the fuse are good. cjs dad, I'm not sure that wrong bulb is causing inherent problem, since with the passenger side indicator lamp harness disconnected AND the driver indicator light disconnected from the main harness running along driver side inner fender, with the ignition switched to the on position, the fuse still blows. Should i be looking at the wires going into the steering column? Could there be a problem withe back up switch as per the wiring diagram?

 

For $hits & giggles, have you reviewed the lighting Troubleshooting diagram in the CSM in the lighting section?

 

OK. Exact same test except w/ car IGN SW in the OFF position. Should be no voltage on either side of the fuse hold adapter w/ car IGN SW in OFF position (keys removed).

 

Vintage chief-with ignition in OFF position (no key in ignition), no light on either end of fuse holder with tester.
cjsdad-I did check aftermarket radio ground wire from radio WAS connected to gray wire going to IGN spot in fuse box. Could that be short circuiting parking light indicator fuse? However, I was pretty sure they worked before with the radio ground wire and gray wire going to IGN in fuse box though.

 

That factory OEM gray wire is not a ground wire. I am assuming the gray wire you reference is a gray wire from the aftermarket radio connected to the IGN spot in the fuse box (as you indicated). That is fine "IF" the aftermarket gray wire is the POWER wire from the aftermarket radio. If it is the POWER wire, you should have no other POWER wire to the aftermarket radio. Only one single POWER wire - which apparently in your case, is the gray wire plugged into the IGN fuse panel spot. Check to see if you have any other aftermarket radio POWER wires connected to any other factory POWER wires. At the end of the day, if you like, disconnect all the radio wires then try the fuse again.

 

I had to read your statement again. The aftermarket radio ground wire should NOT be connected to ANY wire going to the IGN spot in the fuse box.

 

Unless you have the wiring diagram for the aftermarket radio are you just guessing which wire is the aftermarket radio ground? For clarity, there should NEVER be a ground wire connected to ANY power wire leading into the fuse box. You need to be 100% certain of the purpose of that aftermarket gray wire. "If" it's a ground wire and is connected in any fashion to the fuse box it is incorrectly connected. Generally, aftermarket radio wire is RED = POWER; BLACK = GROUND; GRAY = SPEAKER WIRE.

General aftermarket radio wiring schematic:

 

Vintage chief, cjsdad,
SUCCESS! TURN SIGNAL INDICATORS ARE ALL WORKING! Thanks for all your advice and suggestions as well to other contributors. Probably would have never figured it out myself. The problem was with a black wire from aftermarket stereo connected to gray wire from the IGN location on fuse block. I disconnected black wire from aftermarket radio going to gray wire coming from IGN location on fuse block. I replugged in front and rear harnessses and tested all indicators. ALL are working. Thank you so much! Quick question: The aftermarket radio still works, so can I just remove the gray wire from the fuse box since it is not connected to anything? Thanks again!

 

The aftermarket BLACK wire is the aftermarket radio GROUND wire and should NEVER have been connected to ANY wire leading into the fuse box. Sorry, but I'm at a loss here yet. WHICH gray wire are you referring to when you refer to a gray wire? The OEM original equipment gray wire or some gray wire from the aftermarket radio?

 

In the (general) aftermarket diagram I posted (above) you'll note two 12V wires - YELLOW & RED. RED would be plugged into the IGN fuse box blade terminal - this then turns the aftermarket radio ON when the IGN is turned ON. The ACCESSORY 12V YELLOW wire from the aftermarket radio is often hooked up directly to the battery or to a CONSTANT 12V source when the IGN SW is NOT in the ON position e.g. OEM ORANGE wire. The difference between the two is: keep alive memory functions of the radio require a constant 12V POWER source (YELLOW WIRE). The keep alive memory functions of the aftermarket radio will maintain their functions even w/ the IGN OFF. The RED POWER wire when connected to the fuse box IGN terminal spade will ONLY provide power to the radio with the IGN SW in the ON position.

 

In hopes to quickly put this behind you, I am assuming when you refer to a GRAY wire you are referring to the aftermarket radio GRAY wire as there exists no OEM GRAY wire which leads to the IGN terminal spade of the fuse box (that I am aware of anyways). As evidenced by the 1969 V8 A-Body diagram (below) there is no GRAY wire occupied by the IGN SW. To that end, make sure you know the purpose of that aftermarket GRAY wire. If you don't have the wiring diagram look on the Internet for the radio model number to see if you can find the wiring diagram. I'm not aware of any OEM GRAY wire which plugs into the IGN spade terminal of the fuse box. I don't even believe a convertible top SW or electric power seats/windows use an OEM GRAY wire (I could be incorrect).

 

Norm,
The gray wire I refer to looks to be an original wire going to the IGN spade of the fuse box. not sure where it came from or what it was used for from the previous owner. it was NOT an aftermarket wire since the radio installation was fairly recent and the gray wire looks significantly older.. Doesn't matter, as long as turn signals and radio are now functional. I do have documentation for the radio and will need to look into the RED/YELLOW wiring you describe since I don't think its holding memory functions. I haven't used the car/radio much and have been working on slowly putting it back together. (Radio memory functionality was low on the priority list. LOL). Again, thanks for help. It's a relief to know come spring, I will be legal (and SAFE) driving it with working turn signals!

 

The only OEM GRAY wire I'm aware of connects to the 4AMPS fuse INST LPS in the fuse box. Now, w/ that said there exists a very remote possibility (if you have the rear view mirror with reading lamp) there is a gray wire which leads comes from the rear view mirror reading lamp across the top of the windshield (interior edge) then down the A pillar and plugs into a connector on the inside of the dash panel up behind the steering wheel. I mean, I suppose it's possible someone plugged in the wire into the IGN fuse box terminal blade but I suspect this is not likely. That single gray wire to the optional rear view mirror reading lamp switch is the only other known OEM gray wire I'm aware of.

 

OK Good deal. Electrical is always wrought with burdensome diagnostics. Glad you figured it out. Good Luck!

 

Electrical is easy, what is wrong is what is new. I created my own gremlin not too long ago myself.

That gray wire has been causing problems since the first Pioneer SuperTuner radios were put in cars in the '70s. Glad you fixed the problem. Your red radio wire should be connected to the "ACC" circuit (the yellow radio wire under your dash) and the yellow radio wire is the memory lead that connects to a constant 12v source (orange wire under your dash or "BATT" terminal in the fuse box). Verify the labels on your stereo wiring as sime aftermarket units are backwards on those colors.