Ooltewahman Posted April 22, 2015 Share Posted April 22, 2015 I just replaced the circuit board on the gauge cluster. And I traced the brown wire from the harness to see that it was hooked up to the negative side of the coil. This means that the tach itself is bad I'm guessing? Also I read that if u have an hei that it can mess up the tach without a filter on it. I'm sorry to sound like such a novice, but how do I know if I have an hei? Cause I hate to buy a new tach and instantly mess it up. Thanks 1 Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted April 22, 2015 Share Posted April 22, 2015 an HEI will not bother your tach, a MSD ignition could test to see if the tack is getting battery voltage, test the ground and continuity from the tach to the coil, if all 3 of these test good, replace the tach Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 Ok thanks. I checked the continuity to the coil and it was right. Also there is power at the back of the tach. I will order a new tach. I just wasn't sure about needing a filter like I had read. But I don't think I have an hei and I know I don't have the msd ignition. Thanks for helping Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 22, 2015 Share Posted April 22, 2015 Steve, If your tach was working before you replaced the circuit board, did you use the correct circuit board since there are two versions (idiot lights or gauges)? Frankly, I don't believe the tach even connects to the gauge circuit board so I suggest you recheck the tach connections. Photos below are of the correct gauge circuit board and three separate tach connectors. If you have a separate coil (shaped like a small hair spray can) setting beside your distributor, you don't have an HEI - at least a GM HEI (see first photo below). The coil is integrated into the top of the HEI unit as seen in the second and third photos below. When I installed an HEI, I simply moved the brown wire from the negative side of the coil to the tach connector on the HEI. My factory tach continued to work just fine without a filter. Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 The tach hasn't worked since we got the car. I hoped that it would start when I got the new circuit board. The picture of the back of the cluster is just like mine. And thanks for letting me know about the hei. I have a seperate coil. If it doesn't get its power from the circuit board I'm not really sure where it would get its power from. Thanks for ur help Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 I do know that the brown wire that goes to the coil does go to the circuit board Quote Link to comment Share on other sites More sharing options...
monte70car Posted April 22, 2015 Share Posted April 22, 2015 If you go by Dennis picture of his printed circuit board the forth copper tab down from the top is the feed for the tach the stud next to that I believe is the common ground for the dash. On the plug for your dash do you have all 12 slots full with wires? Does the rest of your dash work IE. the AMP gauge, fuel gauge and water gauge? There is a small 2amp fuse in the bottom of the fuse panel that could be blown. When you did the print circuit was the power unplug for the battery? Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 Yes all 12 wires are intact and the other gauges work. I did check that call fuse and it's ok and I did have the battery disconnected. Everything besides the tach works. But those 3 prongs on the back of the tach doesn't have any wires attached to them. I don't think they should tho. I think it's all done thru the circuit board isn't it? Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 22, 2015 Share Posted April 22, 2015 Yes, Steve, I now believe those three studs only hold the tach in place and the two copper studs to the left of them in the photo are the power and ground connections. It sure sounds like your tach may be bad but I would still check or redo those two connections of the tach to the circuit board. The only other thing that might cause a faulty circuit is that big 12-connector plug. It has to be oriented correctly or none of your other gauges would work and the common ground is also apparently good, but that wire (fourth down from the top on the bottom row in the photo, as Robert said) might not be correctly or fully seated in the plug - or the contact surface might be crushed or bent. It would be a shame to replace the tach if it has just been a connection problem for a long time. 1 Quote Link to comment Share on other sites More sharing options...
monte70car Posted April 22, 2015 Share Posted April 22, 2015 Correct its all done through the circuit board. On the studs for the tach you should have a thin plastic washer>metal washer>print circuit>metal washer and nut. I know how to test the lights using a 9volt battery and a double a if not a triple a battery to reset the AMP gauge nut sure how to test a tach. When starting the car does the tach move around or does it just set at 0. When you did the printed circuit did you pull the tach to see if the needle would move? Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 It just stays at zero. Never moves. And no I didn't touch the tach. I just put on the new board. Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 Yes, Steve, I now believe those three studs only hold the tach in place and the two copper studs to the left of them in the photo are the power and ground connections. It sure sounds like your tach may be bad but I would still check or redo those two connections of the tach to the circuit board. The only other thing that might cause a faulty circuit is that big 12-connector plug. It has to be oriented correctly or none of your other gauges would work and the common ground is also apparently good, but that wire (fourth down from the top on the bottom row in the photo, as Robert said) might not be correctly or fully seated in the plug - or the contact surface might be crushed or bent. It would be a shame to replace the tach if it has just been a connection problem for a long time. Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 I agree. I hate to spend money I don't have to lol Quote Link to comment Share on other sites More sharing options...
monte70car Posted April 22, 2015 Share Posted April 22, 2015 Steve the reason I asked about moving the needle is I'm trying to see if the needle many be frozen. At this point I'm going to have to side with Dennis and say the tach is no good. I know the one I just installed in my cluster yesterday has a small circuit board on the backing plate so that could have failed over time. The good news is they reproduce the tach in all redline series like original ones. Since ur pulling the cluster one more time think about upgrading the dash bulbs to LEDS and maybe swap the clock out if it hasn't already been changed. Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 I just now realized that the brown wire is tied to another wire and on the positive side on the coil. I thought the brown wire goes to the negative side? Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 Never mind. It's hooked up right. I was wrong. The brown wire is going to negative. I got too excited lol Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 22, 2015 Share Posted April 22, 2015 Like Robert said, this is a great time to upgrade from bulbs to LEDs and repair or replace a non-working clock. If your clock is not working, you might want to see if you can repair it before you replace it. I was able to repair one and had to replace the other. I made a photo journal of my repair project which you can access by clicking on this link: Repairing a dash clock Also, I upgraded my dash lights to LEDs when I converted from idiot lights to a full gauge dash. The LED stuff is embedded in the photo journal about the dash conversion project which you can access at this link: Upgrading to a factory gauge dash 1 Quote Link to comment Share on other sites More sharing options...
Ooltewahman Posted April 22, 2015 Author Share Posted April 22, 2015 I really appreciate y'all's help. I ordered a new tach. Hopefully get it in a cpl days Quote Link to comment Share on other sites More sharing options...
LostnFound Posted April 22, 2015 Share Posted April 22, 2015 Hey Dennis...was that the tach and gauge kit from sonnie? Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 23, 2015 Share Posted April 23, 2015 Yes, Larry, that's the one. It is all quality stuff, but the instructions suck (unless he's decided to re-write them). Darren and I put together a very complete set of instructions and diagrams that I can email to you if you decide to go with Sonnie's kit. Just let me know your email address. Quote Link to comment Share on other sites More sharing options...
LostnFound Posted April 23, 2015 Share Posted April 23, 2015 Hi Dennis...that would be wonderful. My email address is ldemings@durhamregion.com. I have the kit from sonnie and have been hesitant to install it because auto electrical is like my kriptonite. Thanks for doing that as it will be a huge help I'm sure. Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 23, 2015 Share Posted April 23, 2015 I sent it this morning, Larry. Good luck with the conversion - you will love the results! Quote Link to comment Share on other sites More sharing options...
Murphy Posted April 23, 2015 Share Posted April 23, 2015 What is Sonny's contact info (email or phone) I'm working towards a similar conversion............THX! Quote Link to comment Share on other sites More sharing options...
MCfan Posted April 23, 2015 Share Posted April 23, 2015 Hey, Murray, here's a link to the seller sonnie24 on eBay. Here's a link to his '71 Monte Floor Shift Speedometer with white dial numbers/markings for $149.95. Not sure what else you are interested in since you have already made several mods to your dash, I believe. Quote Link to comment Share on other sites More sharing options...
LostnFound Posted April 23, 2015 Share Posted April 23, 2015 Thanks again Dennis......you rock! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.