LS3R8

Hi All

We managed to fire up my LS3 powered 67 Camaro today and the tacho wasn't working. It is the Dakota Digital VHX model. Checked the wiring and cant seem to track down the problem. Before I contact Dakota I was wondering if anyone else has had experience in mating the ECU and Dakota BIM. All other gauges are working fine.

Thanks in advance.

Walter

lq4elky

Many people on here have had the same problem with many different types of gauges not being able to read the tach signal from the PCM. I don't fully understand it all but it seems like most people say because the engine run off of a pulse that is similar to a 4 cylinder motor rather then an 8 cylinder motor. If your gauge has options to change cylinder modes try putting it on 4 cylinder and seeing if that works. If not do quick search for "tach pull up circuit". Basically what it is, is adding a small resistor from a switched power source and trying it into your tach feed line that runs to your gauge. There are diagrams and different ideas on how to do this so that why you should search and see which one seems the best for you.

99VetteFRC

Here is the pullup circuit I used with my Sun Pro tach. Works perfect with this and 4cyl setting.

lq4elky

Yup that's the same diagram I used to do mine. Worked out great. Thanks for posting that Vette.

rotor vs. piston

iTrader: (3)

can confirm I had to do the same to my VDO tach.

futureuser

iTrader: (1)

The beauty of the VHX gauge is that you don't need a tach signal. I never could find one. Just set the gauge to 1 cylinder and 5 volt signal and then tap any one of your 8 coil trigger wires. Done.

LS3R8

Thanks everyone for your help. Great information.

90FirebirdLS1

Unfortunately there are those of us who would like to try to use our OEM tach. There are no cylinder choices. Nobody reprograms PCMs to change their tach signals. I know people who got their tach to work with just the resistor... not the case with me. Tried that, and the 9117 tach adapter. Fail. Now I'm waiting for a Dakota Digital box to come. Supposedly it let's you change the number of cylinders via Bluetooth. We'll see. Amazon might be getting a return if it doesn't do anything. If it doesn't work. Im going to get Intellotronix totally Digital dash for my 1990 Firebird with LS1.

Anybody with a 3rd gen firebird get their OEM tachometer workin with their LS1? Tell me the solution