Topic: Electrical help

[68 S Code]

Car is back after being at engine guy for some final tweaking. Trying to work through some electrical issues. First one is turnsignal at LH tail light. Front valance, hood blinkers and Rh tail all blink. LH does not. Its not a bulb as I've already changed them twice. I get a taill light but no turn signal. I would have to guess that the turn signal switch in the steering column is OK. Any clues? Should I try to run a ground wire from the socket to chassis? Is there another ground for the harness other than the tiny screw at the trunk latch housing that I'm missing. 

Since we are out back I dont have any brake lights. Checked to make sure I made the connection at the brake switch off the pedal and at proportioning valve. Both are connected. Its not the bulbs as they are already replacements from the first set. Tail lights work and as mentioned the RH turn signal.

Last lighting issue is no back-up lights coming on. Neutral safety switch?

[ruppstang]

A simple way I use to check the turn switch is I have extra 67&68 columns that I lay on the floor and plug in and see if things change. The neutral switch is easy to jumper around to test the switch and back up lights. Marty

[midlife]

Car is back after being at engine guy for some final tweaking. Trying to work through some electrical issues. First one is turnsignal at LH tail light. Front valance, hood blinkers and Rh tail all blink. LH does not. Its not a bulb as I've already changed them twice. I get a taill light but no turn signal. I would have to guess that the turn signal switch in the steering column is OK. Any clues? Should I try to run a ground wire from the socket to chassis? Is there another ground for the harness other than the tiny screw at the trunk latch housing that I'm missing. 

Since we are out back I dont have any brake lights. Checked to make sure I made the connection at the brake switch off the pedal and at proportioning valve. Both are connected. Its not the bulbs as they are already replacements from the first set. Tail lights work and as mentioned the RH turn signal.

Last lighting issue is no back-up lights coming on. Neutral safety switch?

Since your LH running light works, it has a ground path.  It's the same path for turn/brake lights so don't bother with that.  The bulb has two filaments: one for running lights (night light), and a second for brake and turn signals.  Since you don't have a brake light, that is the source for the turn signal via the switch under the steering wheel.  Fix your brake light first, and then your turn signals will probably work.  The proportioning valve sensor is for your brake light signal on the dash, indicating a mis-adjustment of the brake MC, not whether the brake light system is OK or not. 

Power for the brakes (and rear turn signals) originates in the headlight switch, goes through the brake switch, and then through the turn signal switch.  From there, it goes forward to the left and right turn signals, and is combined with the brake lights for the left and right rear turn signals.  My guess is that your turn signal switch is bad or you have bad connections to the left rear.  That wire is green/orange stripe.

[68 S Code]

Randy, it seems that the turn signal switch could be some of my problems. The bulbs are new in tail lights and Ive had two other sets back there so I am eliminating the bulbs from the equation. The headlight switch is also new as that took care of the front running light issue we worked on a few weeks ago. The turn signal switch and the brake switch are still original. I'm wondering if cleaning the pins below the column from the existing turn signal switch is a first option. The brake switch next to pedal assembly housing looks like a pain to work on. Is there a way to test that one? I have two other steering columns with turn signal switches so i could try Marty's suggestion of just plugging them in or i could pull the switches out easy enough as turn stalks are out. If I just lay the columns in the car and connect are there any grounding issues if screws and bolts not holding it in place?

Marty i have two 68 columns which I could try to see if anything changes. Not sure what you mean by jumping past the NSS but I'm going to try to get the tail and brake lights first. Installed an NOS IVR into the gauge cluster and finally have temp and oil registering. The Drake unit was a dud out of the box. Still having trouble with fuel and Alternator but I'm picking up another gauge cluster for testing purposes tomorrow so the dash will come apart for the up-teenth (stopped counting) time.

[ruppstang]

 The neutral switch has 4 wires, 2 are ignition and 2 are back up Lt's. With the plug at the firewall unplugged use the wiring schematic in the service manual to determan what wires are what. Then using a contunity tester making sure that each of the leads are hooked to the back up pair, put the shifter in reverse it should have continuity. If not the NS is bad. Marty

[jwc66k]

One troubleshooting technique I use for brake and turn lights is to active the emergency lights.
Jim

[68 S Code]

Randy, Marty and Jim. Thanks for the advice. Picking up the test gauge cluster tonight so will attack the light issues in the next two days.

[midlife]

The neutral switch has 4 wires, 2 are ignition and 2 are back up Lt's. With the plug at the firewall unplugged use the wiring schematic in the service manual to determan what wires are what. Then using a contunity tester making sure that each of the leads are hooked to the back up pair, put the shifter in reverse it should have continuity. If not the NS is bad. Marty

At the plug from the underdash harness: blue/red are the NSS wires, black/red are the backup light wires.  As always, female sockets are always hot; male plugs receive the voltage/current so that male plugs are never energized when not plugged in (that's to prevent shorts). 

To test brake light switch, unplug from underdash harness and measure continuity across the two pins in the switch.  You should have continuity only when the brake is applied.  If that's the case, then measure voltage at the green/red wire at the plug coming from the underdash harness: that is the hot incoming signal from the headlight switch.

[68 S Code]

Randy, I tried Martys trick with using another steering column/turn signal switch. Viola....I had turn signals and brake lights. Everything worked except flashers. By the way do the tail lights need quite a bit of juice from the battery? With car off and key turned and headlights on the turn signals wouldn't work. Once I started motor everything worked nicely. The test guage cluster also working. Gas level is questionable but even the alternator guage moved to the right of middle a little. With no emergency lights working on the second column it looks like I need a brand new switch. Where do I get one?

[TLea]

68 turn signal switches are notorious for causing multiple issues as a lot flows through them. Having said that the e flashers have a different flasher than turn signal so check that

[midlife]

Randy, I tried Martys trick with using another steering column/turn signal switch. Viola....I had turn signals and brake lights. Everything worked except flashers. By the way do the tail lights need quite a bit of juice from the battery? With car off and key turned and headlights on the turn signals wouldn't work. Once I started motor everything worked nicely. The test guage cluster also working. Gas level is questionable but even the alternator guage moved to the right of middle a little. With no emergency lights working on the second column it looks like I need a brand new switch. Where do I get one?

That's pretty strange that you need the motor running.  With low voltage, the flashers would simply take a bit longer to cycle.

Glad to know you isolated the problem to the turn signal switch, though.

[68 S Code]

Eeee-gad those switches are expensive. Jusy my luck I have the tilt column so its even more. I wonder whats different about the switch? The non tilt column pluged right into the main harness. Randy it was hard to explain but when i first started fooling with the column and no lights on I got the turn signals to work. Almost seemed like sometimes they would be blinking and then a pause and blinking again. i was cycling it from rh to left hand quickly. But when i turned on the running lights it seemed like the side without turn signal would be bright and constant while the one blinking would be dark or on. I was using the back of the garage door as my mirror so not the best. Once I turned on headlamps it wouldn't blink at tail. OK up front but not at tail lamps. For grins I turned the car on and noticed that i had a nice bright lights at the hood and valance. Tail lamps were working as well. Everything blinking nice and bright. Brake lights nice and bright as well. Battery has sat around for about two years waiting for the car to be finished on a battery tender. probably a little low on juice as its been off the charger for the past month while car was away for engine tuning. One flasher was original metal unit while I believe the emergency flasher is the baby blue plastic Tungsol unit. I installed two electronic flashers once I had the lights blinking on the originals. heard they are more dependable and consistant.

I notice that the connector plug looks kind of big to fit around the column opening. Do I have to take the connector off? The second column I have has the connector off of it and seems to be missing the red wire so thats why I didnt try that switch. Only had 9 wires and not 10. Looks like a 68 steering column though. How do I get the pins out? Do the new wires with pins just plug into an old connector? I see the new switches are sold without the connector plug.

[ruppstang]

Rich,
The wiring is the same the difference is in the emergency flasher switch. Yes they are high. You can find a buy on eBay once in a while. Yes you do need to remove the plug. For that you will need a pin extractor, Radio Shack has them. The new switch should have new pins on it. Be sure to keep track of the colored wire positions in the plug. If you get them mixed up you will have troubles that make the current ones look small. Also pay attention to the wire routing in a tilt column. It makes it much easier to get the new in. Good luck Marty

[midlife]

OK...don't worry about the red wire; that's for Cougars and Tbirds and isn't used on Mustangs.  Yes, you have to de-pin the connector so you can fish the wires out of the column (I think that's correct for 67/68; I know it is for 65/66's).  How to de-pin the connector?  Find a ball point pen and remove the guts.  You can slide the pen opening over the male pins and yank the wires out of the connector.  I believe, though, you need to de-pin the female pins.  Use a small jeweler's screwdriver and go opposite of the vertical joint: you'll find a small tab that keeps the pin in place.  Push the tab in parallel to the pin and pull on the wire.  When re-installing, you'll have to use the screwdriver to lever the tab back out before you insert the pin.

Mark the position of each wire/pin.  Plug the red pin into an unused hole and forgetaboutit!

[68 S Code]

Read the last two posts a little late in the day. Spoke with a guy out west last night looking for switch and he mentioned the extractor marty mentioned so bought it today. If I had seen Randy's post could have saved the 6 bucks. Checked ebay but only a couple of used ones and very pricey. No thanks as i have a used one so I know what to expect. The NPD repops probably work but the wire striping is way off. I heard that Daniel Carpenter repops them but dont know who sells his part. Suppose to be closer to original looking. I have someone looking who said he had leads on two NOS ones so lets see what he can find. Thanks for the heads up on looking to see how the wires are routed inside the column as it llok kind of busy in there especially below the plate due to the tilt mechanism. Who would be a dealer for the Carpenter unit as it seems I cant buy direct. Found a guy in New mexico who reproduces these from the original tooling but I wonder if he's just buying the carpenter units. Cant believe there are two guys making the same part from original tooling.