I took my dash apart to add a aftermarket autometer sport comp tach as well as change the bulbs in the dash to leds. My tach light works, but it will not show me hows many rpm's my motor is spinning. When the ignition is off the gauge shows 200 RPM, and when I turn the ignition on the gauge drops to zero, where it should be since the motor is not running. When I start the motor It stays buried at 0 RPM. I have the signal wire running to tach output on my HEI distributor, the light wire going to the gauge section of the fuse box, the ground on the dash and the + to a unused hot accesory under the dash. Next-with the ignition in the off position if I pull the headlight knob out, my lights still come on and if the knob is pulled out OR pushed in my dash lights will remain on. You shouldn't be able to turn your lights on with the key OFF should you? I have a 72 Chassis manual that I used when hooking everything back up, but I didnt really need it the wires much easier to put back than I thought they would be. I did have a couple questions about a couple of ground wires I wasnt sure about where they went but I made sure they both have a nice ground somewhere.....
Cullen, The tach lights will work correctly if you tap into the factory light sockets in the dash. Two grey wires with sockets already on them. Factory intent was dash clock or tach.. They will be taped to the harness near the tach. location. Ground for the lights ppicked up thru the case. Factory shows a metal jumper from the tach case to the speedo case for ground. You can easily make one by simply fastening a conductor from the case to a known ground source under the dash. Look for a black wire. I cannot help with the HEI but standard points ignition had the coil feed from the - side of the coil direct to the tach input, plus a ground. Feeding the tach with + voltage may explain the negative reading as it's seeing an input opposite to what it's looking for.
Cullen, make sure you ground the distibutor to the engine. Ill take a picture of what I am talking about.
Hard to see in there Tyler, but Im pretty sure mine only has two wires on it. The one is the ignition going into the distrubtor and the second is the tach output. My cap even says TACH there, and Im pretty sure there is only 1 connector there.
The tach light works fine, its actually the only one that will turn "off" when the ignition is in the off position. All of the other lights (headlights included) I can turn on even if there is no key in the ignition. My problem with the tach is it does not show engine RPMs, it just zeroes itself when the turn the key on.
on my HEI, I have TACH and BAT marked farthest out on the end, with a pin each. further inboard I have C-, GRD, B+ marked with a pin each underneath. might have to feel under a bit. It looks like Tyler is using the three further "in" posts. Also headlights should come on without a key I thought.
I assumed you hooked everything back up as it was and the dash lights would go off before fine? Only maybe possiable thing it could be , which I have no idea how it could be a problem. But when folks switch their motorcycle lights around to LEDs they often have to add resistors to bring the used voltage or what ever back up to where it was using 12v bulbs. That is or change switches, relays or flasher box to one for LEDs. Don't know all the details though, just know it can be a problem.
The headlight switch works, in all it's positions, regardless of the ignition key position. It is connected directly to the battery circuit.
From Autometers website: My Engine is Running, But My Tachometer Sits at Zero and Doesn't Register Any RPM? Listed below are several common solutions to this issue: 1.) Check connections related to the signal wire (Green wire in most cases). Is the Green wire connected to the proper location (i.e. the negative side of the coil, or tachometer output from an after market ignition)? For further information about Tachometer signal location on your vehicle please see the Installation Information or Ask a Question sections of our website. 2.) Check power to the Red wire. It should register 12 volts (or higher) when checked with a voltmeter with your key on and with engine running. If not, check connections and try a different power source. 3.) Check power to your Black ground wire. If the illumination light also does not function, then the ground is a very likely candidate. To check your ground with a voltmeter, connect the positive of the meter to a known good power source then hook the negative of your meter to the black wire. You should get a reading, of 12 volts or higher. If not, check connections and try a different ground source. I know the ground on the gauge is good otherwise the light would not come on. I know the power source for the light is good because it comes on. The wire for tach in the distrubtor was a pretty easy one so I cant imagine I screwed that up. And since the gauge zeroes itself when the ignition is turned on- that would leave me to belive that the power supply + for the gauge is correct, right?
Cullen, First, the headlights should come on regardless of ignition key position. The gauge lights will come on also with no key in the ignition, but they should go out when you push the lighter switch in. Sounds like you missed a ground to me. The autometer tach will not go to zero when you shut the ignition, it usually goes to 2-300 RPM. When you turn the ignition on, it will zero out. That is normal. I went to the FAQ section of the autometer site and found this. My Engine is Running, But My Tachometer Sits at Zero and Doesn't Register Any RPM? Listed below are several common solutions to this issue: 1.) Check connections related to the signal wire (Green wire in most cases). Is the Green wire connected to the proper location (i.e. the negative side of the coil, or tachometer output from an after market ignition)? For further information about Tachometer signal location on your vehicle please see the Installation Information or Ask a Question sections of our website. 2.) Check power to the Red wire. It should register 12 volts (or higher) when checked with a voltmeter with your key on and with engine running. If not, check connections and try a different power source. 3.) Check power to your Black ground wire. If the illumination light also does not function, then the ground is a very likely candidate. To check your ground with a voltmeter, connect the positive of the meter to a known good power source then hook the negative of your meter to the black wire. You should get a reading, of 12 volts or higher. If not, check connections and try a different ground source.
Larry, I appreciate the help but I posted that exact thing from Autometers website two posts up from yours. From what I can tell it just looks like it isn't getting any signal from the distributor. Lights work and it zeroes when I turn the key on- that tells me it isnt reading the distributor.
O'Reilly sells a a two prong plug in for ignition and tach inputs for the distributor. Just incase the fitting I made isnt working properly or getting a good connection Im going to go ahead and buy that and plug it in and take myself out of the equation, plus it will make for a cleaner looking install under the hood.
Here's where a scope comes in handy. You could check the waveform coming out of that terminal. I wonder if there's no tach output signal at the tach terminal for some reason. The easiest method I think for you Cullen would be to use another car for a tach ouput. That would verify that your tach is capable of working.
UPDATE: Tyler and Ken- the three secondary wires behind the Tach and IGN on the cap are being used, they are bound together and go back underneath the distributor. I did some re-wiring under the dash with my unused hot accesory and power wires for the tach and got it so the tach light only comes on with the gauge lights instead of being on when the key is on. Put the new connector in the distributor (Took a lot of finesse to get it on and it is on TIGHT) and wired the IGN and Tach to those, and started the car up (kinda- the brake booster is leaking horribly and causing a VERY rough idle) and then hooked the battery back up (and had to jump it with my Blazer) and started the car up and the tach WORKED! I know i changed a bunch of things at once but Im pretty sure the signal wire going to the distributor was the cause. The new connector from OReilly fixed it. Now I got to figure out why my Left turn signal light wont come on and I can put the dash back together. i can hear it clicking like it is on, but the light doesnt come on... any ideas?
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Update: All problems fixed. Tach and turn signals working as they should! I had to replace the flasher, the fuse, change bulbs and wedge sockets, re clean all of my contact points and grounds for all of the dash connections- and then the turn signals finally worked. Wipers arent working anymore for some reason, but Ive never used them once in the 3 and a half years I've had the car so Im gonna let them slide. I checked my ground for them, and all my connections and changed the fuse and they still dont work.
