Topic: Turn Signals Do Not Work

[J_Speegle]

No problem.  This thread should turn out to be a good tutorial about how to trouble-shoot electrical issues.

Agreed - will move it to the Processes, Products & Techniques  section rather than leave it here in the Mercury section

[Mark69Sportsroof]

I fully agree.  I'm as green as it comes to car wiring.  But I have learned a lot, used tools for the first time and starting to understand what Randy is saying.

Thanks Mark   

[67gtasanjose]

OK, on a serious note, without any "Chardonnay..." (just for today )
Since we have moved this over to "General Discussions ~ Processes & Techniques" the information already shared to this point MAY not match up to every example out there (example, pin connections in the TS harness to main under dash harness, the O.P.'s Mercury looks to have a curved plastic bulk connector at this juncture point where I know other examples do not). Another situation is that the '66 and older Mustangs DO NOT incorporate the hazard flashers into the steering column, though the basic function of the Turn Signals is 100% the same. (67-up has more wiring to work with in the column)  I'm not trying to nit-pick details since I am sure the information is most likely 100% correct for the O.P's example.

What I am asking is, that for clarity purposes, that perhaps not only the wire 'color' be described but to possibly consider including the circuit number that Ford engineers provided in the descriptions/comments. Ford used the same circuit numbers for many years just like they usually used the same wire colors for many years. This added "circuit number" (with the wire color) could aide in translations to other applications for future readers of this thread. I know when I trace out schematics I like to use both so those readers who are "wired" like I am, this could help us a LOT!

Just a suggestion, not trying to derail or hi-jack the thread in any way. To explain what I am suggesting, using Midlife's previous quote (with only detailed wiring colors), I have copied his text and added (high-lighted in red) the particular circuit numbers. I have confirmed the circuit numbers using the 1967 Osborne Assembly Electrical Manual, page 96, that these wiring colors shared earlier MATCH 100% to my wiring diagram of my 67.

OK...you're getting power to the turn signal switch.  Let's turn to the turn signal switch itself.  First, disconnect it from the underdash harness and you'll need to set your DVM to resistance, ohms, or the upside down U.  No need for the key to power anything.  Put the turn signal switch lever in the neutral position and look for resistance between the blue wire (circuit # 44) and the following: white/blue(circuit # 49), green/white,(circuit # 50) orange/blue(circuit # 5), and green/orange(circuit # 9).  These wires are in the center of the turn signal switch connector, top and bottom row.  You should see high resistance between blue and these wires.

Now put your turn signal switch to the down or left side position.  Measure resistance again as above, and you should get low resistance for the green/white (front) (circuit # 50)and green/red (rear)(circuit # 10) lamp turn signals.  High resistance for the other two wires.

Put the turn signal switch to the up or right side position.  Resistance should be low between blue(circuit # 44) and white/blue (front)(circuit # 49) and orange/blue (rear) (circuit # 5)wires.  High resistance for the other two.

Now then...brake lights come from the green wire(circuit # 511) below the blue wire(circuit # 44).  You can measure resistance between the green wire(circuit # 511) and the four above.  You should see high resistance for the white/blue(circuit # 49) and green/white wires (circuit # 50)and low resistance for the green/red (circuit # 10)and orange/blue wires(circuit # 5), with the turn signal lever position in the neutral position. 

Post the results and I'll bet 67gtasanjose's afternoon chardonnay glass that the turn signal switch is bad.

I think I copied over the correct circuit numbers, anyone is welcome to double check.

My money, (no booze, or Chardonnay ) is on connection issues and/or incorrectly pinned connector(s) (pins plugged into incorrect cavity perhaps) We'll see. Randy does these things far more often than I do and either is suspect at this point of time for the O.P.'s situation IMHO

[midlife]

Fair enough to include circuit numbers, but a lot of folks don't use that and go by wire colors.  And yes, TS connectors vary in design from 64.5-66, 67, 68, and then 69-72 and 73, but wire colors remain the same.

And for what it is worth, the Mercury Parklane's TS connector matches the 69-72 design. 

In my mind, what's important is the process of trouble-shooting to isolate where the problem is, not the specifics of a particular design.  KISS: keep it simple, and test in a rigorous, systematic manner will always get you to the root of the problem.

[67gtasanjose]

In my mind, what's important is the process of trouble-shooting to isolate where the problem is, not the specifics of a particular design.  KISS: keep it simple, and test in a rigorous, systematic manner will always get you to the root of the problem.

+1           I Agree with the KISS methodology...I thought the different TS Switch/Steering column bulk connectors used across various model years and various Ford applications could cause confusion now since the topic got moved to this particular "Processes, Products & Techniques"heading. Now, with the circuit number AND the wiring colors combined with a Ford Schematic found in any assembly manual or Ford Service Manual, by matching the circuit number to the wiring color key chart, you can very easily identify where each wire is supposed to be found in the TS Switch/Steering column bulk connector. That has to be of help to people. I think this thread can and will help many, even more-so now it is across multiple years/applications, not limited to only the O.P's Mercury example or any single model year of our Mustangs.

[Mark69Sportsroof]

Ok let me try to explain what I did. To many blue wires. So I used the blue wire on the left side of t/s switch. The side where the t/s lever screws in.

Ok that blue wire to the e flasher blue wire. I got 1.5 to .01 ohms. It always decreased.

Then with t/s lever down on. I used t/s blue wire to grn/white and got 1.3 to .01. Then blue to grn/red and got 1.6 to .01

With t/s up from the blue to white/blue I got 1.1 to .01. Then blue to orange/blue I got 2.1 to .01.

This is with the t/s switch not attached to the steering column.  That's because some of the wires are connected to the back side of the switch.

So am I using the correct blue wire to measure from when testing the other ones?

With t/s switch attached to the steering column I get the same blue to blue wire reading. With the t/s lever down I get nothing from the blue wire to other wires. With the t/s lever up from the blue to white/blue I got 1.0 to .01.

It seems I got more and better results with the t/s not attached. I'm not sure why. It does have the tilt wheel option

Thanks Mark

[midlife]

Ok let me try to explain what I did. To many blue wires. So I used the blue wire on the left side of t/s switch. The side where the t/s lever screws in.  Is this looking at the turn signal switch connector going to the steering wheel?

Ok that blue wire to the e flasher blue wire. I got 1.5 to .01 ohms. It always decreased. There is no e-flasher blue wire.  The e-flasher wire colors are white/red (385 which is power to the turn signal switch) and red/white (383, which is power to the e-flasher can). 

Then with t/s lever down on. I used t/s blue wire to grn/white and got 1.3 to .01. Then blue to grn/red and got 1.6 to .01  I suspect you are measuring the system with bulbs in the circuitry.  What I want you to do is to simply unplug the turn signal switch connector at the column and probe the pins going to the steering wheel, isolating the turn signal switch itself from the rest of the car.  You should not get much variation of resistance.

With t/s up from the blue to white/blue I got 1.1 to .01. Then blue to orange/blue I got 2.1 to .01.  Ditto. 

This is with the t/s switch not attached to the steering column.  That's because some of the wires are connected to the back side of the switch.

So am I using the correct blue wire to measure from when testing the other ones?  There is only one solid blue wire (44) that comes from the turn signal flasher can.  The only other blue wire is the horn output, typically blue/yellow (482) which is located on the inner curve for your vehicle and opposite the 44 wire.

With t/s switch attached to the steering column I get the same blue to blue wire reading. With the t/s lever down I get nothing from the blue wire to other wires. With the t/s lever up from the blue to white/blue I got 1.0 to .01.  I don't understand this test.  You say the t/s switch attached to the steering column...is this different than above?  Or are you saying you've plugged in the two connectors and are probing from the flasher can pin  to the other wires?  How are you able to probe these other wires with the connectors mated? 

It seems I got more and better results with the t/s not attached. I'm not sure why. It does have the tilt wheel option  Please explain in more detail what you mean "the t/s not attached".



Thanks Mark

Ideally, you could perform the same test on the turn signal switch with it entirely removed from the steering wheel column, but that means de-pinning the connector and that's a PITA.  The test I asked you to perform essentially probes the installed turn signal switch, which sits behind the steering wheel, with it electrically isolated from the entire car.  With your readings of 1.1 to 0.1, that tells me you are measuring the resistance of the bulbs (1.1 ohms) to ground and straight resistance (0.1 ohms) when the flasher can is doing its thing.  Electrical trouble-shooting of lamps is best performed when the bulbs are removed, as the resistance of the bulbs are reasonably low (~ 1 ohm) so it provides ambiguity as to the results. 

The key is to isolate small sections of the wiring and test each one at a time.  If all sections function correctly when isolated but fail when they are connected, then the problem is at the connectors.  Let's first determine if each section is good first.  Isolate...isolate...isolate.

[Mark69Sportsroof]

Here is pic of the front side

[Mark69Sportsroof]

Here is the back side

[Mark69Sportsroof]

OK let me clarify to the best of my abilities.

The t/s switch was attached to the steering column but the wires were not attached to the plastic dash connector.  I was looking at the t/s switch with the blue wire on the left side next to the green wire. There is a bolt between them.  See pic above.

On the right side of the t/s switch as I'm facing it is the e flasher button I push to engage the e flashers.  There are 3 wires.  Blue, white w/red stripe and white w/green stripe.  See pic above.

When did the test, I had battery connected, key in off position, t/s switch attached by 2 screws to steering column and the plastic wire connector not attached  to anything.  I just realized the main dash t/s wires that go through the firewall were disconnected at the first connection inside the engine bay.
I was trying to trace my wires and connections previously.  There are bulbs in front and rear turn signal housing.

OK Randy if I understand the next step is as follows.

Unplug the t/s switch plastic connector from the main dash plastic connector.  This is already done when doing the early test today.

Test the blue t/s signal wire with the previous listed colored wires to check the readings.

Early today I had the t/s switch attached to the steering column and got only 2 readings.  When I removed it from the steering column and totally disconnected it,  I tested the front blue wire on the t/s switch with the wire connectors on the backside is the t/s switch I got more readings.  Now I realized I was totally confused.   

Sorry for all the headaches.  Mark

[midlife]

Ahhh...I now see the disconnect (pun intended).  Forget about the wiring within the turn signal switch on top of the steering column; instead, consider the entire switch a "black box", of which you only see the pins in the connector that mate to the underdash harness.  There may well be additional wires (blue?) within the turn signal switch itself, and that is what is confusing you.  Forget about what's on the back and the front...and only consider the pins on the connector that mates with the underdash harness.  We all know the wires (numbers and colors and positions) on that connector, and they are the inputs and outputs.  With a given input signal, the TS switch should give the proper output signals if the TS switch is working correctly.  That is what we're looking for: only inputs and outputs (along with the position of the lever).

With the connector disconnected from the underdash harness, the TS switch now becomes completely isolated and can be probed for proper operation.  Go back and read my original instructions and see if it now makes a bit more sense.

For those trying to follow along, here's the position of the turn signal switch connector, as seen looking at the underdash harness side.  The TS switch side will be a mirror image.  This is the standard arrangement for 69-72 Mustangs and the 68 Mercury.

Outside row, left to right:
blue 44                     turn signal flasher input signal
orange/blue 5          right side rear turn and brake output
green/red   9           left side rear turn and brake output
white//red  385       e-flasher/4 way input
yellow   460             horn power input

Inside row, left to right:
blank
green   511              brake light input
green/white  3        left front turn signal output
white/blue    2         right front turn signal output
blue/yellow  482     horn output

This test is actually best done with the steering wheel installed, since sometimes the rivets on the back of the switch touch the steering column and get shorted out to ground inadvertently.  I always apply black electrical tape over those rivets as extra protection.  But...for the time being, do the test with the steering wheel off which makes accessing the connector a bit easier.  Let's see if the innies produce the correct outies.

[Mark69Sportsroof]

I'm glad you confirmed that I'm not crazy...lol.  I will test the wires tomorrow at lunch time.  You show a "blank"  spot on inside row left.  I don't have a blank spot.  On the original t/s switch every hole had a wire. 

I had a light blue.  I will send a picture of the original t/s switch plastic conection.

Thanks Mark

[Mark69Sportsroof]

Here it is

[midlife]

My schematics for the Mercuries don't indicate what that wire is for.  In later years, it is used as a door-ajar chime signal.  It is not relevant to turn signal operations. 

1968 schematics, as published by Ford, as notoriously incomplete.

I notice you are showing me the turn-signal switch side of the connector.  Theses switches are generic and not specific to any particular Ford model.  Some models have this extra wire, but most models in 1968 did not use it.  I'll bet its mate on the underdash is blank.  If so, just leave that wire alone.

[ruppstang]

I test my turn signal switches by having another column that I know the switch works in. I unplug the connector lay the test column on the floor then plug it in and if all works I order a new switch. It is also helpful to take a picture or make a drawing before you remove the wires from the connector.
Hope this helps someone.