I've got quite a doozie of a problem going on with my turn signals... I'm looking at about 15 hours of solid work on this b****...

My turn signals all worked perfectly until one day when I turned my key on and heard a POP. I checked the fuses and found the turn signal fise was blown, so I replaced it. New fuse in, I turned on the key and POP. Here's where the fun begins.

My assumtion was there was a short somewhere, so I started at the front driver's turn signal and tested between the signal + and ground. 10-some-odd ohms. I started wiggling around the harness and found the resistance changed between a direct short, open circut, and everything in between. So I pulled the harness out and inspected each and every wire end-to-end. It was in perfect condition, all the way through.
I did some more wiggling around and checking every wire that runs anywhere near the signal harness, but found nothing.

I tried moving to the other side of the car and found the passenger signal to be shorted too, but wiggling around that area changed nothing.

On a possibly unrelated note, I went to the back of the car and noticed the passenger side bulbs are all brighter than the driver's.

All the bulbs in the rear, however, work. Just the signal does nothing.

Voltage to the park lights is 12.4V with the ignition off. However, the signal lights also get 12.4V with only the park lights on. This is consistant to both sides of the car.

While I was again testing resistance to ground through the power wire, I had accidently left the park lights on. It was now OL between the signal power contact and ground. Turning the park lights off changed the resistance to be 0.2 ohms. Switching back and forth park lights on and off yeilds the same results every time, no matter what harnesses I play around with.

And that would be where I thought I was in over my head and needed help.

 

If I had to guess, you are sort of on the right track, just looking at the wrong place. Assuming it is a tilt column, it is pretty common to have the wires wear a bit in the column then short at some point. It would be the hardest yet easiest place to test. You can start by not snaking the wires out, just test at the bottom connector to ground, one wire is probably going to be shorted in the column. If you find a wire that shows little to no resistance at ground (make sure you have the keys off and probably pull the fuse) you have found your culprit.

Most common things on the outer harnesses is a loss of ground, but that usually will not trip a fuse. That signal switch in the column will though, since it has power running through it and the column is grounded to the body.

 

I'll most definately be doing that tomorrow.
Any ideas on why the park lights change the circut so it's no longer shorted to ground?
Oh by the way I also turned the park lights on, put in a new fuse, and turned the key on. The fuse blew just the same way.

 

I don't know why the park lights would have any effect, unless you are getting some cross current through the bulb.

The reason I suspect the turn signal switch is because it is only energized when the key is on. So, you turn the key on, power flows up the wire to the switch, hits ground and blows the fuse. I have also seen this when it is one of the two wires for direction, meaning either it blows when the left or right signal is switched on but not the other one. Since this is blowing as soon as you turn on the key, it is most likely going to be the main power wire to the switch.

Edit: I got thinking about it, when the signals are off it will sometimes appear that the line is shorted to ground. When you apply the park lights it will 'jump' the coil in the bulb and appear that there is a bit of power to the wire, thereby making it appear that it isn't shorted to ground. It most likely was never shorted to ground, it just appears that way because the switch itself is 'off'.

 

So are you saying that when signals are not engaged the bulb will be getting ground through both terminals, and then It is switched to an open circut when park lights are on because it only has one ground?
I'm not sure that made any sense, but I know what I'm thinking with it. Hope you do too...

 

Yeah basically. It isn't a true ground, but it can appear to be a ground due to being an open circuit. It is not really getting ground, but it can appear so. There is still only one true ground, but it can appear to be a ground.

I have seen it where someone will turn on a park light, but they only see a dim light. The ground is disconnected, but the second power feed acts as a partial ground allowing the bulb to light slightly. It will never reach full brightness without a short in the second line, but it will light slightly. I have always assumed it was making a bit of a highly resistant jump to ground somewhere along the second power feed, allowing the appearance of a ground.

For the record, I am not a trained electrical guy, I am only speaking from experience. I have worked automotive electrical for a few years, and I am a trained shade tree mechanic. Everything I listed here is based on my own past experiences, but I am not a genius, I just play one on the interwebs.

 

I spent some time today and pulled my steering column apart, but didn't find a short.
I also traced the wiring between the non-power side of the fuse and the back-up lights so check that harness. I lost track of it when it went under the floor, but didn't find any problems all the rest of the way.
I did my clutch a couple weeks before the signals (or back-up lights?) started acting up, but don't expect I did anything wrong as everything was perfectly functional for that lovely two weeks.
Any other ideas?

 

I don't know off the top of my head what else is on that circuit, but I would say eliminate them one at a time. Basically disconnect the turn signal harness, then power on the key, if the fuse doesn't blow you found your area. Then each other system until you find the one that is failing.

Beyond that, I really don't know in this case. Something on that circuit is bad, but what it is is not so easy to figure out. One other thing to try, remove the flasher relay for the turn signals, and see if that solves the problem.

 

Pull apart the connector for the tail lights behind the driver's side rear storage compartment (the harness will be coming through the body out of the bottom of a black box like protector, follow that to the end of the harness) and try powering up again. Could be as simple as a blown bulb in the affected tail light or a damaged wire in one of the sockets. Only way to tell if the wiring is broken would be to check the resistance on the wires between the tail light harness connector and the socket, and of course the bulbs are checked with an extra bulb.

Would also help to know if you have base/Formula or TA/GTA tail lights, as the signals run differently.

 

It has to be something internal, as the bulbs are not powered up by turning the key on. It is something on that circuit that is energized when the key is turned on, so unless your turn signal is turned on when you turn the key on, which would tell you which side is the problem, it is going to be something simple inside the car.

 

Okay, so I should be searching inside instead?
I don't know if it makes any difference, but the hazards work.

 

Hazards are a bit different, they use their own flasher, independant from the turn signal. They also have constant hot power, so they can run even when the key is off, while turn signals are powered by ignition hot.

 

Update: I've done more probing, disconnecting, testing, and blowing fuses. No luck.
I tried getting one of the guys at my shop to work on it who is really good at electrical, but he found nothing as well.
In the small panel where the flasher and hazzard relay are, I was expecting to find the signal relay as well, but it didn't seem to be there. Not unless is's the white box? But there are also no blue wires running to that panel, which is what comes out of the fuse.
Anyone know where the relay for the signals are? Searching the forums turned up nothing about my year of car.
Thanks

 

I don't know why GM didn't put the turn flasher in the center with the other one, but they didn't... Not like there isn't a space for it or anything (which there is). The thing is hiding under the dash on the passenger's side of the steering column. Looks just like the other one in the relay center, but it will be on a pink connector pretty much just hanging there under the dash. What I did with mine was I busted the terminals out of it (the connector) and put the flasher in the center with the other one.

Question, have you done any work to or under the dash lately that could have pierced a wire causing a short?

 

I'll go have a peek around as soon as I'm done posting this, but I've been through there a few times and seen no such thing...
I haven't done anything but swap the kenwood deck for an alpine deck, but some of the previous owners did a little work...
The car used to be wired for subs, it used to have a remote start in it, and it used to have a fuel pump disabler switch. All of these were removed (mostly) before I bought the car.

 

May want to do a check to make sure none of the gazillion dash screws isn't piercing the wiring harness and shorting out the turn signal wiring (or whatever wiring it may be affecting). I had done some work to the wiring under my dash a couple of years ago, tying everything that was added into the main harness and cleaning up the mess, only to find out that one of the dash support screws (or was it the radio pod screw? I don't quite remember) had pierced the blue turn signal wire and didn't turn on the turn signals. Had to bypass the wire with another blue wire I had to get the signals working again.

 

Since the hazards are working and I am assuming that all the lights are flashing for the hazards, that tells you that your wiring is fine for the outside of the car. The hazards are going to use the same wiring on the outside of the car since they light up the turn signal filaments in the bulbs. If I could see a wiring schmatic for your car, I could probably tell you exactly where to look. Should be something very simple.

 

jermdm: Here's the link that I gave to the guy at work.
http://www.austinthirdgen.org/index.php?pid=19

Maverick H1L: I tried to find that relay under the dash, but couldn't find it. Unless it's up as high as behind my gauges, it's not there.
Also, that blue wire coming from the switched side of the fuse is in perfect condition, with not even a nick on it as far as I can see. I lost what appears to be the wire when it ran up through the dash to the passenger side.
However, I may have been tracing the wrong wire because there's a lot of blue wires.
If I'm right, it goes from the fuse, over the steering column (into the switch at some point where I can't access it?) and then up through the dash to the passenger side.
My plan is to pull the rest of the dash and trace it as best as I can tomorrow when it's light again.

 

Ok. By looking at the schematic, you have a dark blue wire coming from the fuse box to the turnsignal flasher. If that fuse is blowing when you turn on the ignition, you have a short to ground in the wire. Keep in mind, that dark blue wire also has a splice in it going to the gear selector switch or back up switch(depending on if you have an auto or manual trans) for your reverse lights. I assume that your reverse lights arent working either. That dark blue wire can be the only place that will blow the fuse when you turn on the ignition as long as the turnsignal switch or gear selector/back up switch isnt stuck in the on position and the short is downstream from there. What you need to do is find the turnsignal flasher and unplug it. After that, get to the gear selector switch/back up switch, which ever you have and unplug that. Then you want to replace the fuse in the fuse box and turn on the ignition. If the fuse still blows, you know the short is in that dark blue wire and nowhere else. I would check the wiring connector at the gear selector switch/back up switch for damage first since that would be easy to do. I have a spot circled in the pic for the circiut I'm talking about.

 

So I just decided to do the smart thing and check that wiring diagram that I found, and it's saved me a lot of work already.
It says that the fuse is hot in run (signals on), on test (key on?), and start (same as key on?) which would explain why the fuse is blown as soon as they key is turned on.
If I were to key on, then put the fuse in, it may not blow?
However, I am now only going to check the blue wire between the flasher and fuse, as knowing locations of the components along the circut tells me that everything after the flasher is fine.
I'm now also wondering about the backup lights being shorted or drawing excess current somewhere, as I had the transmission out to replace the clutch. The only problem is, there is constant 12V on the hot side of the fuse with the key on, but without a fuse in place there is still 5V on the other side of the fuse, which makes me think there is a short to power somewhere?
Do I have to pull my transmission again to fully trace the backup wiring?

 

jermdm: I have the manual transmission, but as far as I know the backup sensor is inside the transmission, as there is no wiring at the shifter?

 

The connector for the back up light switch on your manual trans is a 2 wire connector on the outside of the trans. Probably somewhere on the middle of the trans case on the side. Might be the only wires going to the trans unless your speedometer is driven by a electrical speed sensor which that sensor is on the tail shaft of the trans. If the speedo is cable driven, then the back up light switch wires are going to be the only wires going to the trans. Since you just had the trans out, I can almost bet that you have pinched those wires somewhere along the trans.

 

Well in that case I'll check out around the transmisson as well. Do you reckon more likely this would be the problem than the signal circut?

 

I would say this is where the problem is. Look at the harness going to the back up switch attached to the trans. There should be a dark blue wire going to the switch which is the 12 volt ignition power wire which is powered by the turnsignal fuse. Make sure that wire isnt pinched/grounded somewhere along the trans or hanging down somewhere melted to the exhaust. Can be easy to happen when putting the trans back in. I know this is the least likely sounding spot to look but I'm just putting 2 and 2 together since you just had the trans out to replace the clutch.

 

jermdm: I just don't know how to thank you.
The very top bolt on the bell housing pinched the blue +12V wire, causing it to wear and eventually short out.
I've spliced in a new wire (I had some of the same size and color kicking around anyways) and replaced the fuse, so now I have turn signals and back-up lights again.
Also thanks to everyone else for your help in solving this problem.
Thanks, '89 Bird =]

 

Glad I could help out. Sometimes you will find the problem in the least likely area. You probably never would of thought you would find the problem to non working turnsignals down by the trans. Thats where a schematic come into play. Have fun driving your bird.