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MustangGT

Turn signals not working

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Had an incident with the car, '69 Mustang, while on Hot Rod Power Tour last year - long story short, the driver side marker light ended up getting ripped out the socket and the wires ripped apart.  The long version of the story would go into the details about other body damage done to the front drivers side - but that is for another day.

Took the car to a body shop and they fixed all the damage which included splicing in a new driver side marker light.  Picked the car up and before I left I checked all the lights - but not the turn signals.  When I got home my wife asked why I didn't use my signals.  Well I was using them they just weren't working - I called the shop and told them about it but said I would look into myself since I figured maybe they disconnected the turn-signal flasher (they also had to replace the antenna and wire going to the radio).  

Finally today, due to warmer weather and having time I pulled the radio to check.  The flasher was installed so I figured may it just died - so I grabbed another one from the local parts store.  I know I should have just switched it out with the one for the emergency flashers since the flashers work great - but I didn't since the store was close by.  Installed the new flasher still no turn signals. 

If I press the brake and then select left or right that tail light will go out but not blink (switching from left/right the accompanying light will go out and not blink).  The front signals do nothing and the hood mounted ones do nothing.  I checked voltage and the wire (orange with yellow stripe) going into flasher unit and I am getting power when selecting left/right.  The voltage is a little lower compared to the power going to the emergency flasher power wire but not much lower.  When I check the output side of the turn-signal flasher I am getting approx 3.5volts compared to the output side of the emergency flashers where the power is close to 12volts when energized.  I switched the old turn-signal flasher with the emergency flasher and the flashers work - I put the one that was in the emergency flashers into the turn-signal and with same results of no working turn signals.

I am running LED bulbs (from West Coast Cougars) in the rear and front -- all lights/signal were working before the HRPT incident.

Any hints??? 

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Sounds like when they spliced the wires to side markers, they mixed the wires up. On the How to section, there are wiring schematics Mach1 Driver prepared. May be they will help you identify which wires are mixed up during splicing.

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I looked at the diagram (3 of 4) and it doesn't appear to show a relationship (connectivity) between the turn signals and side marker lights.  As I mentioned - the 4-way flashers work great.  All lights dash, hood, front & rear blink when putting on the emergency flashers.

I did peak at their splice job and they wrapped the daylights out of the wire so without tearing apart their tape job I cant see if they switched the wires.   I also checked the wiring diagram my Haynes manual and even if the wires were switched it doesn't appear that should/would cause the behavior I am seeing since they aren't common with the turn signals. 

I must be missing something...

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They probably spliced the left and right side marker lamps (should be running lights and ground ---brown and black) into turn signals and ground).  Are there any lights on (other than headlights) when the headlight switch is fully out?  If so, that's where the brown wire for running lights ended up.  The front parking lamps should only be on with the first detent on the headlamps and turn signals. 

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I am thinking you possibly have a high resistance connection, or a bad ground somewhere.  That would explain the 3.5 volts.  As Midlife suggested.....if you pull the headlight switch out one position, do the parking lights work?  

I would pull the parking light connector apart, and run a temporary jumper from the battery to the parking light.   The parking light plug has 3 connection points...the two hot connections are the one for the blinker, and one for the parking light, using a dual filament bulb. Then there is a ground wire to the plug as well..   You should be able to get the light to come on with either of the two hot connections.  I think the brown is the parking light, the blue is the blinker, and the black is ground.  

Another thing I wanted to point out, that may not have any bearing on the outcome is the emergency flashers do not go through the ignition switch, neither do the headlights, parking lights, or brake lights.  The directional lights do go through the ignition switch.  You may have jarred something loose in your accident.

 

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The lights behave normally with regard to the switch.  When pulled to the first position the lower front lights are on as well as the marker lights on the left & right and rear (along with the tail lights).  When pulled out all the way the lower lights go out and all of the other lights remain on.  Regardless of light switch position the flashers work as expected - lower front lights blink.  The flashers work regardless of ignition switch position (as expected).  The signal power wire going into the turn signal flasher unit doesn't get power unless key is turned and the turn signal is moved up/down.

As I running the tests above this evening I noticed something I couldn't see in the daylight yesterday.  The hood signal indicator illuminates but very dim and it doesn't blink.  If I switch move the lever for a left/right the hood indicator lights up (dim) but doesn't blink.  This behavior happens regardless of the position (all the way in, first position, or all the way out) of the headlight switch.

Lastly, with the emergency flashers on (everything blinking - hood, lowers, rears) if the brake if pressed everything stays illuminated (no blinking).  Release the brake and everything starts to blink.  Although, I think this is normal since I seem to recall that happening before the 'incident'.

 

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20 hours ago, MustangGT said:

Lastly, with the emergency flashers on (everything blinking - hood, lowers, rears) if the brake if pressed everything stays illuminated (no blinking).  Release the brake and everything starts to blink.  Although, I think this is normal since I seem to recall that happening before the 'incident'.

 

Above you state "everything stays illuminated (no blinking)".  It is normal for the tail lights to stop blinking when pressing the brake, but hood and front turn signals should continue to flash. The marker lights should not flash on a 69.

Since this all started with side marker lights, it could be that they installed 70 side marker lights on your 69. The 69 has a wire to the bulb and a ground. The 70 doesn't have a ground-  it has a wire leading in and out. You can see the explanation of this rather bizarre 70 circuit in How To "1970 Mustang Exterior Lights" if interested. 

Do the usual stuff- check all connections and check grounds at every bulb.

 

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Right now, with the flashers on and the brake pressed all blinking stops - tail lights, front signals, and hood.  The maker lights don't blink at any time. 

The shop "only" replaced the drivers side outside marker light and spliced-in a new socket.  They used 7.234 miles of electric tape to wrap the wires 2 of them coming out of the side marker light socket (just like on the unmolested passenger side marker light).   When the weather clears up I will pull car out and rip off the tape to trace the wires from the socket to wherever they end up.  Given that the original socket/wire was ripped out and there were only two wires for them to attach two I can't understand how they could have messed it up.  But given some of my other recent findings from their work I guess anything is possible.

If, they somehow "switched" the wires coming out of the side marker light socket going into the harness wouldn't that prevent the light from functioning?   My thought has been that if they crossed the wires the light wouldn't function.

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I haven't looked at the marker light in ages. The diagram shows a ground wire and one to power the bulb. I'm not certain if the ground side is also grounded at the receptacle. It doesn't make a lot of sense for Ford to do both, and if it isn't it makes the 70 circuit easier to construct- the only change would have been wire.

I think its more likely that you have bad ground(s). Clean and reattach. Disconnect the battery and do ohmmeter tests from the bulb ground contact points to the chassis. Also check the grounds from the engine to firewall, and at every light. The big culprits are the 1157 bulbs which have two filaments and a common ground. If you loose the ground to that bulb the power goes through the unused filament and to another bulb in the circuit. There are lots of them, and the combinations are very hard to predict.

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Swapping the wires to the side marker wouldn't have any effect as long as they are the right wires to begin with.  Current flows into the bulb on the hot side and back to ground on the low side, reversing it will still light the bulb. You could pull the bulb (opening the circuit) and see if anything changes.

You said you are running LED lamps so I assume you know you need a different flasher for LED's - the OEM units are bimetallic and require a good slug of current to work.  LEDs don't draw enough and will exhibit the symptom you see - constant ON. Might want to look at that.

I know you said they worked before but you also said you swapped in a new flasher so you might want to look into that. Good luck, electrical problems can be the worst!

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Before the weather started getting warmer so I could continue more troubleshooting I took the car back to body shop and gave them a chance to find/fix the problem.  This ended up being a bust -- they said they couldn't find anything and once again reassured me that all they did was to splice in the new socket.  I double-checked their splice before taking it back to them so I knew that wasn't the problem.

Now that the weather is warmer I have decided the start the troubleshooting up again - need to get the car ready for the '18 HRPT.  I have double/triple checked the under hood harness and can't find anything obvious.  I am back to thinking the tech(s) at the shop might have ripped out one of the under dash harness ground connections - as I mentioned in my initial post they had to run a new antenna wire.  I peaked at the different manuals I can really only see only one ground wire on the under dash harness - is that correct?  I want to get an idea on what I need to be on the look out for before I pull the dashpad (what a joy that is) off to further investigate.

Like 69RanvenConv said in the above post "... electrical problems can be the worst!".  So I am open to suggestions. 32 days and counting before I am supposed to head out.

 

 

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One ground on the underdash, behind the headlight switch; one ground on the tail-light (near the license plate light), and one on the headlight harness, near the voltage regulator. 

My troubleshooting tips for turn signal lights: remove all bulbs but one and see if the system works.  If not, remove that bulb and go to another spot and see if that works.  When you finally have at least one working bulb, start adding bulbs to that side until it stops working.  The last bulb you put in is where the trouble lies.  Work on one side then the other. 

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Midlife -- I just pulled all the bulbs (didn't pull the hood mounted turn signal ones) still no joy.  I did try disconnecting the hood mounted harness and that had no affect either.  Looks like I will be pulling the pad and looking in the car.

For giggles I also swapped in another steering column w/ harness to troubleshoot the steering column switch -- results were the same which tells me my column switch should be good.

 

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1 hour ago, Midlife said:

One ground on the underdash, behind the headlight switch; one ground on the tail-light (near the license plate light), and one on the headlight harness, near the voltage regulator. 

My troubleshooting tips for turn signal lights: remove all bulbs but one and see if the system works.  If not, remove that bulb and go to another spot and see if that works.  When you finally have at least one working bulb, start adding bulbs to that side until it stops working.  The last bulb you put in is where the trouble lies.  Work on one side then the other. 

nifty approach Mid

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Like midlife mentioned, the only underdash ground is near the headlight switch.  Another problem area on these cars is all the connectors in the headlight harness in front of the radiator.  Other than those connectors, bad bulbs or poor grounds.  It works with the 4-way flashers because with all the bulbs on there is enough current through the flasher for it to operate, even with a bad ground, bulb, or connector somewhere.  I've replaced many bulbs that were bad but still would light.

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OP said he's running LED lamps so he should have solid state flashers. You might try checking the turn signal flasher to see if it's still good. Check the grounds on the taillight sockets. too. The buckets are insulated by rubber gaskets so they run a ground wire from the bulb socket to chassis. I've knocked those spade lugs loose futzing around in the trunk on occasion.

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"When I check the output side of the turn-signal flasher I am getting approx 3.5volts compared to the output side of the emergency flashers where the power is close to 12volts when energized."  

  As a test seeing that there isnt enough current to work the t/s flasher make a jumper and put it in its place . Then look for whats working and whats not, bright dim etc.  Using a test light to diag these issues (power and ground faults) should make it easier to locate your issue. 

As far the side marker light being wired incorrectly (parallel to the front turn signal) it would not cause a t/s disruption unless it was some how shorted and wired to the turn signal wiring and blowing a fuse.   Wiring the ground from the side marker to the turn signal wire  will operate the light normally when the park lights are on using the ground path thru the  turn signal filament to ground. Turn signal operation  will take the ground away when the signal light flashes putting 12 volts on the  side marker ground causing the light to flash a "wig wag" effect .

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