View Full Version : Hooking up a Tach.
02-19-2003, 08:57 PM
I'm wanting to hook a Tach on my 93 Dodge 5.9 turbo. Any suggestions on a Tach to use and where to hook it up to motor.
02-19-2003, 09:17 PM
Man I love the thought of getting a tach, but i really like the stock one that is so hard to find. Wish I could get one that was identical to original, dodge sais tough luck none around any more and is discontinued. I have a friend in australia and he's checking if there are any around on dealer shelves down there. If anyone finds one I sure would like to have it.<br> As far as hooking up a tach, your truck (as well as mine) is prewired with sensor on motor already and wires for hookup below steering column. Isspro makes a harness to plug their tach right to it. I want original because the redline is in the right spot (even with pump turned up a little) and I dont really want to carve up my dash to mount a non original pod. (pillar is reserved for pyro and boost)<br> -RATCHET-
02-19-2003, 09:59 PM
what about a 1990..how hard would it be...is the wiring there also??
02-19-2003, 10:24 PM
For 89 and 90 you will have to get an alternator driven tachometer. These model years did not have crank triggers. I had an 89 with a Motorola alternator tach and I actually liked it better than the stock one in my rig. The stock tach doesn't have enough graduations on it. Just in grads of 250 rpm... 1000, 1250 1500 etc.. Really hard to see what my actual idle RPM is.. The alt tach I had was in 100 rpm grads.<br><br>Check out some diesel shops to see what they have available if the Isspro isn't your style. There are many brands available, but not too many that are small enough for a dash mount.<br><br>J-eh
02-21-2003, 09:01 AM
I'm also curious about putting a tach in my 90. Could someone expand on the whole altenator tach thing. How it work? How to instal? where I can get one? Thanks.<br><br>Brian
02-21-2003, 03:11 PM
The alternator tachs are really quite simple. Basically you tap into one of the fields of the alternator to pick up a pulse from the alternator. From this pulse frequency the tach determines the speed of the engine. Now to tune it to the actual speed of the crankshaft, as most alternators are about 1.5 to 1 speed ratio, you will need to have a diesel shop put on a phototach or similar to set the tach for accurate speed.<br><br>On mine,I just took off the back plate of the alternator and there are 4 fields with screw connections to the main rectifier of the alternator. A loop terminal was connected to one of the fields and went to the tachometer. There was a screw pot on the alternator to adjust the speed.<br><br>I used to have pictures, but I must have deleted them by mistake. :-[<br><br>J-eh
02-23-2003, 09:51 AM
Isspro makes a kit Part # 8912 for the pre 92's that mounts down by the crankshaft pulley. It installs easy. JW
Isspro's kit (for the models without a crank sensor) is designed to use two magnets glued to the damper to trigger a sensor that you put uner one of the screws on the oil pan. I am using this sedning unit on my truck, without the magnets, and it picks up off of the notches in the damper just fine (like the later model's senders). You just have to get the sending unit very close to the edge of the damper.<br><br>I personally like the idea of taking the tach signal directly from the crank, though the alternator taps work just fine.
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