Help - I fried the turn signals!

Sweeny Todd · 07-28-2015, 05:33 PM

I accidentally grounded out the blinker wire. It blew the fuse. I replaced the fuse and now the turn signal doesn't work (front or rear) and neither does the hazard flasher on that side. The other side works great.

I replaced the fuse and I replaced the flasher relay. The flasher relay now buzzes when I engage the turn signal on that side. On the other side, it works fine.

How do I troubleshoot this? I can't find any obvious signs of damage to the wiring harness...

Joe Bob · Joe Bob's Garage

Replaced the bulbs?

Sweeny Todd · 07-28-2015, 06:02 PM

Didn't do that. Is that a thing? Can I really burn out the bulbs by shorting the circuit?

Joe Bob · Joe Bob's Garage

One bad bulb can screw up all the signals. At least it has with my SC.

Sweeny Todd · 07-28-2015, 06:12 PM

I'll test them all tomorrow.

SpyderMike · 07:24 PM

what year car?

what side turn signals?

do the indicators work on the gauge?

at any rate, the circuit is probably gonna look like this (for an SC):

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part2-2.jpg

If I read this right, for turn signal operation, power comes in through the fuse 11 through the hazard switch 15 through the turn signal relay 49 to 49a and back to a common connection 49a on the hazard relay. Then it goes to the turn signal switch 49a where it branches to each side. If your problem is on one side only, then it is downstream of there.

From the turn signal switch, power taps in parallel to the gauge indicator and the front and rear indicator lights. So if the gauge indicator is not working, then the problem could be in or near the switch.

For Hazard light operation, power goes into the Hazard Relay and our L and R for Left and Right, respectively.

If the problem was just in the switch, then you could make an argument that the hazards should work. If the hazards don't work also, then the problem should be in the common area between connection T5-6E and fuse 10 (for a left hand side example).

Note that the rear turn signal lights tap off upstream of fuses 9 and 10. Did you short a front turn signal or a rear one? The rear ones appear to be unfused all the way back up to fuse 11 (a 16 amp fuse) which would have taken out both sides. If you shorted a rear turn signal, then you could conceivably have damaged the section between T5-6E and fuse 10 - if it were the left hand side as an example.

I think...

Mike

SpyderMike · 07-28-2015, 07:46 PM

Here is the schematic for a later car...similar flow:

Sweeny Todd · 07-29-2015, 07:13 PM

Found this, but I haven't found time to work on it. Might be able to tomorrow after lunch for a few minutes.

Will post a followup.

SpyderMike · 07-29-2015, 07:45 PM

if you answer of few of the questions i posted, then we can help you too.

your call.

Sweeny Todd · 07-30-2015, 04:35 AM

Thanks Mike! This helps a lot.

My answers are inline.

H

Quote:

Originally Posted by SpyderMike

what year car? 1986

what side turn signals? right side (passenger side)

do the indicators work on the gauge? yes for both turn and hazard signals.

at any rate, the circuit is probably gonna look like this (for an SC):

http://www.pelicanparts.com/911/911_Parts/Electrical/911_electrical_82SC_Part2-2.jpg

If I read this right, for turn signal operation, power comes in through the fuse 11 through the hazard switch 15 through the turn signal relay 49 to 49a and back to a common connection 49a on the hazard relay. Then it goes to the turn signal switch 49a where it branches to each side. If your problem is on one side only, then it is downstream of there.

got it - downstream of 49a - meaning towards the lights.

From the turn signal switch, power taps in parallel to the gauge indicator and the front and rear indicator lights. So if the gauge indicator is not working, then the problem could be in or near the switch.

For Hazard light operation, power goes into the Hazard Relay and our L and R for Left and Right, respectively.

If the problem was just in the switch, then you could make an argument that the hazards should work. If the hazards don't work also, then the problem should be in the common area between connection T5-6E and fuse 10 (for a left hand side example).

I'll start here - T5-6E - this is the most likely place given your scenario.

Note that the rear turn signal lights tap off upstream of fuses 9 and 10. Did you short a front turn signal or a rear one? The rear ones appear to be unfused all the way back up to fuse 11 (a 16 amp fuse) which would have taken out both sides. If you shorted a rear turn signal, then you could conceivably have damaged the section between T5-6E and fuse 10 - if it were the left hand side as an example.

I shorted the Front Turn signal.

I think...

Mike

Sweeny Todd · 07-30-2015, 06:16 AM

OK. More discovery. On the flasher. 31 is ground. 49 is 12v all the time. 49a is the side that "blinks".

With meter on 49a

When turn stalk is down - left, lights blink normally and meter shows 12v's blinking.

When turn stalk is up - right, lights do not blink and meter shows 4v's.

With meter in turn signal plug behind the right headlamp, shows 4v's when bridged between either indicator wire and ground.

I think this indicates I have a short between the flasher and the turn signal, right?

H

tirwin · tirwin's Garage

Could you also tell us the year of your car? (Hint: put it in your sig. so you won't have to answer this from now on.)

SpyderMike · 07-30-2015, 08:06 AM

not necessarily a short...maybe a high resistance.

Indicators working (if they both light up with similar brightness) leads one to believe that the wires up to the fuse are probably okay.

I would measure the voltages at the input (top) side of the fuse 10. Then I would check the voltages at the bottom of the fuse. Any variance would suggest a fuse holder or fuse issue (sometimes the fuses don't seat well). Make sure the connections for the wires to the fuse are sound - clean copper and tight screws. If they were disturbed or damaged during the fuse blow then that could cause it.

Be careful not to short out anything while around that fuse panel! You might want to disconnect the battery after measuring the voltages.

Sweeny Todd · 07-30-2015, 10:36 AM

Car is a 1986 3.2 Carrera.

It appears it was a combination of things. The turn signal was plugged in backwards, so the turn signal was activating the smaller and therefore lower resistance bulb. This combined with a bulb in the back that was out seems to be the problem.

Having said that, the bulb in the back isn't out. So now I guess I have to pull the housing and troubleshoot that.

If you don't have one, a benchtop 12v DC power supply is a wonderful thing to have. I recommend it.

I'm getting closer. The lights that work on the right side now blink fast.

Evidently, the flasher buzzes when it doesn't have enough load on it to cause it to flash. I confirmed this on the benchtop power supply.

I'll post the final resolution when I have one. My least available resource at the moment is time.

H

Sweeny Todd · 07-30-2015, 10:38 AM

Oh. and there are no brake lights. So that'll be next.

SpyderMike · 07-30-2015, 10:43 AM

sorry, my assumption by your original post was that things were working fine until you shorted the wire.

SpyderMike · 07-30-2015, 10:45 AM

oh, and brake lights are relatively easy...two switches near the brake booster. power goes from the fuse to both switches and then back to bulbs. they are dual filament bulbs. one filament is for park function and the other for stop function.

Sweeny Todd · 07-30-2015, 11:59 AM

Car was in mothballs. Bringing it back to life. Worked when parked. Lol.

The turn signals are now sorted. The ground wire from the brake lights was totally disconnected - broken off the ring connector. New connector and we're off to the races.

I'll tackle the brake lights this weekend. Like you said, that's an easy one.

Thanks everyone!

LLPP - Long Live Pelican Parts!

Hal