Gerald Morris
Senior Member
Greetings C-body Moparians! This evening I rejoice in having found the failure point in the turn signal circuit on Gertrude, our 1968 Newport ragtop. I had surmised late last year that the long summer heat had damaged the new Shee-Mar turn signal switch I had replaced the original with just 2 years prior, having found a small bit of metal loose in the steering column nearby. Alas, my flawless, trouble-free replacement of the SM-107 this time didn't restore the right turn signal! Having already checked the indicator bulb and circuit board with a cursory visual inspection, I broke out both of my test lamps, my favorite voltohmeter, a couple test jumpers and a fresh pack of Lucky's to find the Trouble.
I tested for the pulse DC at pin 9 on the Instrument Lamps Connector and found it good. Since my test lamps also retain the venerable Edison resistance, my flasher (which putatively shouldn't DEPEND on such!) responded well, and I knew that the problem was in the wiring or circuit board above the main instrument panel: the one showing from left to right the left turn signal indicator, the cold engine lamp, the hot engine lamp, the high beam indicator in the middle, directly above the steering column, the low oil pressure warning lamp and finally, the right turn signal indicator. Since the circuitboards are conveniently split with the right board having only the turn signal and oil pressure indicators, I was able to isolate the problem in short order. I plugged the 10 pin connector back in, then tested the 3 pin plug meant for the right board. Again, I had good voltage there, but, no turn signal indication, and no blinking anywhere in the LEDs I use front and rear...
So, I checked the bulb, which dimly lit. I checked another such from the spare instrument panel I got with this car, and inspected THAT board. Turns out it's also compromised, so I bega repairing the conductive runners o the original (to this car) board. I ran a strip of foil from the grounded lug to the ground side of the bulb, checked with that, to no avail, then ran another strip over the old conductor to the hot side, ot eglecting to wrap some of the copper foil around the connecting post which plugs into the 3 conductor plug. I replaced the dim bulb with a fresher one from the other panel, and FINALLY....FIAT LUX!
First, restore the ground...
Then the hot side, all the way to the plug-pin, to the tan wire on the left end of the plug as shown here.
So, for a fraction of a cent's worth of copper foil, I've restored the right turn signal to full functionality in our family car! Mind you, it took about a day's trouble shooting and careful, tedious work to arrive at this solution, so I thought some of you might spare yourselves some trouble with this or similar problems, which I know plague a number of you.
I hope in another year or 18 months to be able to more systematically dress and clean up my spare boards, restoring them and testing them at leisure instead of under the duress of necessity. I saw some mistakes I had made in installing that Shee-Mar switch the first time, which I avoided happily this time, so I expect no trouble from that element again for some decades... I'm amazed at how forgiving these simple, rugged old systems are!
P 8-93, 1968 Chrysler Service Manual
I tested for the pulse DC at pin 9 on the Instrument Lamps Connector and found it good. Since my test lamps also retain the venerable Edison resistance, my flasher (which putatively shouldn't DEPEND on such!) responded well, and I knew that the problem was in the wiring or circuit board above the main instrument panel: the one showing from left to right the left turn signal indicator, the cold engine lamp, the hot engine lamp, the high beam indicator in the middle, directly above the steering column, the low oil pressure warning lamp and finally, the right turn signal indicator. Since the circuitboards are conveniently split with the right board having only the turn signal and oil pressure indicators, I was able to isolate the problem in short order. I plugged the 10 pin connector back in, then tested the 3 pin plug meant for the right board. Again, I had good voltage there, but, no turn signal indication, and no blinking anywhere in the LEDs I use front and rear...
So, I checked the bulb, which dimly lit. I checked another such from the spare instrument panel I got with this car, and inspected THAT board. Turns out it's also compromised, so I bega repairing the conductive runners o the original (to this car) board. I ran a strip of foil from the grounded lug to the ground side of the bulb, checked with that, to no avail, then ran another strip over the old conductor to the hot side, ot eglecting to wrap some of the copper foil around the connecting post which plugs into the 3 conductor plug. I replaced the dim bulb with a fresher one from the other panel, and FINALLY....FIAT LUX!
First, restore the ground...
Then the hot side, all the way to the plug-pin, to the tan wire on the left end of the plug as shown here.
So, for a fraction of a cent's worth of copper foil, I've restored the right turn signal to full functionality in our family car! Mind you, it took about a day's trouble shooting and careful, tedious work to arrive at this solution, so I thought some of you might spare yourselves some trouble with this or similar problems, which I know plague a number of you.
I hope in another year or 18 months to be able to more systematically dress and clean up my spare boards, restoring them and testing them at leisure instead of under the duress of necessity. I saw some mistakes I had made in installing that Shee-Mar switch the first time, which I avoided happily this time, so I expect no trouble from that element again for some decades... I'm amazed at how forgiving these simple, rugged old systems are!
