69 gauge/ lights circuit borad

[My 69 Mach 1]

I am not new to this forum but have not been on for a few yrs and had to start all over.

 

ok , been working on the car and had dash and gauge cluster out  , everything worked when I took it out , now the dash lights do not work .

i have power coming into the circuit board ( Varified ). All other lights work.  If I jump power from the power from plug to the clock lights circuit  they will work . Can't test anything else .  I am assuming the board somehow got damaged in the process of removal or reinstalling ?

except for the gas gauge , everything else runs to a seperate gauge cluster independent of the dash cluster and as the gas tank was empty , not sure if the gauge's would have been affected ?

i know midlife is on this forum , hoping he has some advice seeing as he is the electrical guru.

 

thanks

[Midlife 814]

Look at the dash cluster pin for that line (blue/red wire) and it's mate.  Since the trace works for another powered line, the problem has to be at the connector area or your headlight switch was not engaged or rotated in the wrong direction.

[My 69 Mach 1]

Ok , I think I'm a little dense here.

are you telling me the blue red / wire is the wire from the switch and if so would the companion be where ?

if the blue / red wire is from the switch and I use a test light grounded out and it doesn't light , am I to assume I have a bad  light switch ?  By the way my gas gauge works and so does the alternator gauge .

the plug that goes to the gauge cluster has numbers on both sides from #1 up . Does the wiring diagram show how the wires correspond to the numbers ? I have looked and I haven't seen it.

ya know , I can install , disassemble , reassemble and trouble shoot a million btu boiler system   but I can't figure out this simple wiring issue.

 

Thanks 

[Midlife 814]

The blue/red wire is for dash lamps, and the headlight switch must be pulled out and rotated such that maximum voltage is available.  The power goes through a fuse on the fuse box first, so the fuse might be blown or have bad contact there.  The headlight switch might also be bad.

Many schematics show the pin-outs on the dash cluster connector.  For the tach-dash cluster, blue/red are pins 2 and 5; for the standard dash, the pin is #12. 

[My 69 Mach 1]

Ok , I think I got it/

when I ground out my test light 17 & 16 have power but 15 does not , then  I turn on the light switch and there is power at 15 . however I tried dimming it to see what happens and no noticeable change , I thought the light would dim down ? and #15 wire is green black .

anyhow , what's your thoughts ?   

[Midlife 814]

Dude: you really need to understand the function for each wire before trying to trouble-shoot things.  stated before: pin 12 for standard dash cluster or pin 2 and 5 for blue/red: those are dash lamp wires. You can figure out the function of the circuit board trace by examining the position of the bulb and what should be seen on the front of the dash cluster, and then follow that  trace back to the cluster. 

Pin 15 is Green/black is the high beam signal.  Why are you testing 16 and 17?  Those are ammeter lines: always hot and unfused. 

 

So let's cut to the chase and I'll give you the complete pin-out of the dash cluster connector for the standard dash:

 

 

[My 69 Mach 1]

Your talking to a plumbing / heating guy , I'll tell you trouble shooting a furnace / boiler wiring system is a cake walk compared to this . 

But thanks for all your help , I'll get it sooner or later . 

[390mach1 49]

I'm having this issue right now too. I've replaced the circuit board on the back of the cluster the constant voltage regulator, and all new led blubs and bulb sockets. At first I only had one blub light up in the center od my cluster and I tried moving bulbs around and ended up only getting one turn signal bulb to work.  below is the link to CJ for the LED bulbs that I got.  Maybe I should try just regular bulbs?

http://www.cjponyparts.com/scott-drake-instrument-panel-led-set-1971-1973/p/SD7173GABL/

 

[My 69 Mach 1]

I have the regular bulbs in mine , like I mentioned prior to removing the gauge cluster and reinstalling . Mine worked , my light switch is also only 3 yrs old and it a NOS switch .  for now mines going back in as everything else works and the car needs to be at the transmisson shop for repairs.  

 

[Mach1 Driver 560]

3 hours ago, 390mach1 said:

I'm having this issue right now too. I've replaced the circuit board on the back of the cluster the constant voltage regulator, and all new led blubs and bulb sockets. At first I only had one blub light up in the center od my cluster and I tried moving bulbs around and ended up only getting one turn signal bulb to work.  below is the link to CJ for the LED bulbs that I got.  Maybe I should try just regular bulbs?

http://www.cjponyparts.com/scott-drake-instrument-panel-led-set-1971-1973/p/SD7173GABL/

 

If you can connect a light bulb across a battery and make it work you can figure this out. A LED is a Light Emitting Diode. Think of it as a fancy light bulb, the difference being if you hook it up backwards it won't light. Its doubtful that all of the LEDs don't work, so more than likely you aren't getting power to the LEDs.

So put a light bulb across a battery. Add a switch to turn it on and off. Stick a rheostat in the line (it can be anywhere) and you can dim the bulbs. The rheostat is a variable resistor- the resistance varies as you turn the knob- more resistance, less light. Now add a fuse to protect against shorts and you have the entire circuit.

The negative side of the battery is grounded. The power is connected to the positive side of the battery and goes through a series of 6 wires, various splices and the firewall plug and finally arrives at the light switch. If you need me to list all those wires and splices I can, but I would just check for power at the light switch terminal A. From there to ground you should get 12v. From terminal A it goes through the light switch, through the rheostat and out at terminal I. Check for power at terminal I with the switch on and the rheostat turned all the way up.

Wire 19 blue-red connects to terminal I. This goes down to the fuse block and through a 4A fuse. Wire 19a goes from there to a splice to wire 19C to the circuit board plug. Randy listed the plugs numbers above, my diagram doesn't have them. Check for voltage at the plug. From the circuit board plug it goes to the individual lights. My wire diagram shows 8 lights via the circuit board, and they all connect via the circuit board to ground. Make sure the ground trace on the circuit board is actually grounded and you have the entire circuit.

[My 69 Mach 1]

1 hour ago, Mach1 Driver said:

If you can connect a light bulb across a battery and make it work you can figure this out. A LED is a Light Emitting Diode. Think of it as a fancy light bulb, the difference being if you hook it up backwards it won't light. Its doubtful that all of the LEDs don't work, so more than likely you aren't getting power to the LEDs.

So put a light bulb across a battery. Add a switch to turn it on and off. Stick a rheostat in the line (it can be anywhere) and you can dim the bulbs. The rheostat is a variable resistor- the resistance varies as you turn the knob- more resistance, less light. Now add a fuse to protect against shorts and you have the entire circuit.

The negative side of the battery is grounded. The power is connected to the positive side of the battery and goes through a series of 6 wires, various splices and the firewall plug and finally arrives at the light switch. If you need me to list all those wires and splices I can, but I would just check for power at the light switch terminal A. From there to ground you should get 12v. From terminal A it goes through the light switch, through the rheostat and out at terminal I. Check for power at terminal I with the switch on and the rheostat turned all the way up.

Wire 19 blue-red connects to terminal I. This goes down to the fuse block and through a 4A fuse. Wire 19a goes from there to a splice to wire 19C to the circuit board plug. Randy listed the plugs numbers above, my diagram doesn't have them. Check for voltage at the plug. From the circuit board plug it goes to the individual lights. My wire diagram shows 8 lights via the circuit board, and they all connect via the circuit board to ground. Make sure the ground trace on the circuit board is actually grounded and you have the entire circuit.

Thank , for us non technical people . This has made more sense to me than all the wiring diagrams.  

[det0326 179]

LED's will not dim. I replaced mine with led's and they will stay the same brightness regardless of where the light switch knob is turned . Some may dim I don't know but mine will not. I have read that if you put 1 incandescent bulb in the circuit they will dim but I tried that also, the incandescent one will but the led's won't.    You can also get LED's that are bi directional and you won't have to worry about if they are connected correctly or not.

[Mach1 Driver 560]

2 hours ago, det0326 said:

LED's will not dim. I replaced mine with led's and they will stay the same brightness regardless of where the light switch knob is turned . Some may dim I don't know but mine will not. I have read that if you put 1 incandescent bulb in the circuit they will dim but I tried that also, the incandescent one will but the led's won't.    You can also get LED's that are bi directional and you won't have to worry about if they are connected correctly or not.

I've read the same thing- keep a incandescent in the circuit and it will dim. Some people swear it works and others say it doesn't. Yes there are bi-directional LEDs which are really two LEDs with anodes and cathodes reversed in the same package.

If they don't dim you can get a Auto Meter 9114 LED Dimmer Module which sends out pulses- the further apart the pulses the dimmer it gets. I'm guessing this is a variable square wave generator of some sort.

[Midlife 814]

I had a request to post the pin-out of a tach dash cluster.  Here it is for a 69; the 70 is almost the same except for pin 6, which changes to red/yellow, the same as pin 8.

[Mach1 Driver 560]

I had a conversation with a guy over on VMF who actually used the Auto Meter 9114 LED Dimmer Module ($39 at Jeggs). It ties into the light switch so when you turn the knob it adjusts the light level. To quote: "It does provide a nice range of adjustment, I am very happy with how it works and looks".