Baffling Electrical Problem

Don Z. · 11-23-2003, 07:35 AM

Now how redundant is that?

'74 Carrera Targa.

My turn signals stopped working. The fuses are all OK, the hazard lights work, as do the parking lights (i.e. shut the car of with the turn signal lever pushed right or left and the appropriate parking lights are lit).

Also, when the emergency brake is pulled, the red warning light on the dash neither lights nor flashes.

I'm thinking flasher relay... but before I track one down, does anyone have any other suggestions? Thanks.

Formerly Steve Wilkinson · 11-23-2003, 07:41 AM

Typically, the problem is in the stalk unit itself. Since a hazard/flasher relay is $48 (don't try a non-OEM unit), what I'd to is the old remove/disassemble/clean/replace routine on the stalk unit first. Clean the contacts, make sure they're all "contacting," etc., that none are bent or worn, and see if that fixes it. If the hazard lights work, I suspect it's not the relay.

Stephan

Don Z. · 11-23-2003, 05:12 PM

See, I thought it would be the stalk... but the parking lights working seem to indicate the stalk is OK. Ditto the lack of blinking when the parking light is pulled.

Also, for some strange reason... I checked power at the fuses with a voltmeter. No voltage through the fuses, no voltage when the positive lead is on the box and the other lead is grounded. All the other fuses have power along the bus, but not those three... weird.

rvdv · 11-23-2003, 05:22 PM

Does your emergency flasher work? That would tell you if you had a problem with the stalk.

jeff m · 11-23-2003, 06:12 PM

There is one source of "flashing" for the hazards turn sigs and brake indicator. (that's the reason S. W. suggested the stalk, still could be)

Go to tech information get the diag for your car, don't forget the stalk turns on the flasher and directs it the correct side.
For faulting purposes choose one lamp, say front left, locate flasher unit and turn sig switch.
You could pull all the fuses clean fuses check tension of holders while you are there.
Using logic there are four things that turn on the flasher; left turn, right turn, hazard, and brake (Handbrake and pressure differential)
You have one out of four and the three are the ones with the ignition ON.

The euro one side parking lights working do not help.

Jeff

Don Z. · 11-23-2003, 07:37 PM

More info...

Also out are the brake lights and the back up lights.

I need to check in the daylight, but it looks like I'm not getting power to the fuse box for the three fuses that cover the front right turn signal, front left turn signal, and the brake/flasher relay/back up lights fuse.

The hazards are working.

I'll check again in daylight, wire by wire to try and see what's going on.

I hate electrics.

Z

jeff m · 11-23-2003, 08:48 PM

Check wiring from ignition switch.

fintstone · fintstone's Garage

Don,
On your '74, brake lights, the flasher relay and back-up lights all come off fuse 11 (16 Amp). Hazard is off fuse 17. 11 is probably your problem.
Stoney

Don Z. · 11-24-2003, 09:45 AM

It just gets more confusing...

For starters, I checked the fuse box... the PO seems to have wired it just a little differently than it should be wired. For example, the fuses that are supposed to work the headlights (5 through 8)? They are really wired into fuses 11 through 14. So I'm not even sure which to check, though I do know the fuses 8 and 9 do not have any power going to them, even with the key on.

Jeff mentioned checking the wiring at the ignition switch. That all seems connected, but I did notice a two wire plug that's not connected. There's one black wire, and one purple one... Not sure what they are supposed to be connected to... I did notice a little white socket to the side of the ignition switch that looks like something is supposed to be connected there... the black/puple plug does not fit... but nothing else around there looks like it should. Does anyone know what this is???

Help! This is driving me nuts! Clearly, the next major project for this car is to completely re-do the wiring harness (this time, correctly!), but until then... I need to get the indicators working before someone rear-ends me. Thanks!

fintstone · fintstone's Garage

make sure you count from the front of the car
1=foglights
2=license plate loght
3=front and rear parking lights (right)
4-front and rear parking lights (left)
5=low beam (right)
6=low beam (left)
7=high beam right
8=high beam left
9=front flasher right
10=front flasher left
11=brake lights(rt and lft), flasher relay, back-up light
12=.....................

Don Z. · 11-24-2003, 01:25 PM

The "count from the front of the car thing is a bit confusing...

I mean, I tried counting both ways... and I'm still having a problem with some of the items matching up... to "add interest", the fuse block is numbered underneath the fuses... but numbered back to front.

I'm officially baffled...

fintstone · fintstone's Garage

If you are standing in front of the car (near the headlights) looking into the luggage compartment, the closest fuse to you is #1, the foglights. If you start there and count the fuse positions (occupied or not) to 11 in the direction away from you, either that 11th fuse (should be a 16 amp), power supplied to that fuse, or corrosion on that fuse connection is most likely your problem. That is because it is the only common link to all of your problems. You can check for power with a meter or test light or replace the fuse. You will probably need to turn on the ignition for power at this connection. If you do not have a spare 16 amp, try swapping in the 1st fuse (should also be 16 amp) to see if that fixes it. I know that the fuse setup is confusinig, but keep in mind that sometimes more than one fuse may affect a particular circuit..for example a light might well be fused searately from the relay that controls the light. If I am not clear on how to read the panel, please refer to the explanation below:

According to you owner's manual, "The numbering used in the following list begins with the front-most fuse in the car's forward direction."

1=foglights
2=license plate loght
3=front and rear parking lights (right)
4-front and rear parking lights (left)
5=low beam (right)
6=low beam (left)
7=high beam right
8=high beam left
9=front flasher right
10=front flasher left
11=brake lights(rt and lft), flasher relay, back-up light
12=Relay of the rear window defroster, freah air blower, control light of the rear window defroster
13=Windshield wiper
13=Electric sunroof, rear window wiper
14=Electric sunroof, rear window wiper
15=Auxiliary heater, cigarette lighter, control light of blower switch
16=Power windows
17=Emergency flasher
18=Interior lighting, clock, glove compartment light, luggage compartment lighting

Don Z. · 11-24-2003, 03:08 PM

Thanks...
I think what is happening with the numbering is that the PO replaced the fuse panels at some time. The first fuse (fog lights) is actually broken and not connected. That would have been an "important fuse" if it were in its proper place, so he switched it.

Also, this all really started when I looked in there and noticed that the PO put a 25 amp fuse in every slot! Problem began when I switched them out for the correct amperage. Nothing has blown, just no power to three of the circuits

Right now, key on or off, I have no power at all to numbers 9, 10 and 11. No power at the fuse, or at the wires leading in to the fuse. It really doesn't make much sense, but I can't make out where it would be shorting before that.

I may need to "take this one in to someone", as I don't have a lot of experience with wiring. For example, when I converted to H4s with relays, somehow, my rear hazards are OK, but in front, there's no flash on the passenger side, and the driver headlight flashes instead of the turn indicators... how could I have screwed that up? At least I know what I'll be doing Thanksgiving Day.

Thanks for all your advice... I'm still trying to figure out where that purple/black plug goes under the dash...

Z

Don Z. · 11-24-2003, 04:36 PM

And to really make things exciting...

On the ride home today, the wife said "did you fix it?" and hit the wipers (thinking she was hitting the turn signals). The wipers worked... then I hit the signal stalk... and they were working! How the hell...

I guess it's "fixed" for now... until I can find that short.

Z

fintstone · fintstone's Garage

Glad it is working! You will probably see the problem again though. Sound like you have a poor connection at your fusebox...probably at fuse 11 again. Make sure there is a good, tight connection between the fuse and terminal. An ink eraser is good to clean terminals with. There were a couple of typos in the first list of fuses...here is a corrected version with the fuse sizes added:

1=foglights-16 amp
2=license plate light-5 amp
3=front and rear parking lights (right)-5 amp
4-front and rear parking lights (left)-5 amp
5=low beam (right)-8 amp
6=low beam (left)-8amp
7=high beam right-8amp
8=high beam left, high beam control light-8 amp
9=front flasher light right-5 amp
10=front flasher left-5 amp
11=brake lights(right and left), flasher relay, back-up light-16 amp
12=Relay of the rear window defroster, freah air blower, control light of the rear window defroster-25 amp
13=Windshield wiper, winshield washer pump-25 amp
14=Electric sunroof, rear window wiper-16 amp
15=Auxiliary heater, cigarette lighter, control light of blower switch-16 amp
16=Power windows-25 amp
17=Emergency flasher-16 amp
18=Interior lighting, clock, glove compartment light, luggage compartment lighting-5 amp

Fuses in engine compartment

1. Sportomatic-5 amp
2. Starting valve (Carrera only)-8 amp
3. Rear window defroster-25 amp

Relays in fuse box

1. Air Conditioning
2. Fog lights
3. Horn

Let me know if you need any more help. By the way, did you add relays for your H1s? If not, you should. The Sucro kit is reasonably priced..(about $20 I think), and not too hard to install.

Don Z. · 11-25-2003, 06:43 AM

Thanks... Yes, I got the relays from Wayne... I figured it was easiest to get everything from one place. I do need a better way to mount them though. Right now, they're just in the bucket behind the lights.

I used 10 Gauge Marine wire (believe it or not, it was cheaper by about 20 cents a foot than the 12 Guage!), and a nice Marine fuse box, which fortuitously has four extra slots in it. My soldering needs to be better, but I'll do that again in a few weeks with an EE friend when I see him. I'm planning a trip to Germany over the holiday, and plan on picking up some heavy duty sockets, and some Narvo bulbs... but I'll be in there again later today. Now that the turn indicators are working, I noticed that in addition to the "flashing headlight" when the hazards are on, I'm also flashing that headlight when I want to turn left. I must have crossed over a ground or something... it's not doing it on the right side...