Tach problem - Page 2

TheJeanyus · 07-24-2006, 10:49 PM

If you hook up the voltmeter backwards, the signal will be negative. If you had hooked it up the other way, it should have been positive. Like Brian said, though, it should be AC, not DC, meaning the polarity would alternate.

Italian LX · 07-25-2006, 06:52 AM

Quote:

Originally Posted by TheJeanyus

If you hook up the voltmeter backwards, the signal will be negative.

Quote:

Originally Posted by TheJeanyus

Like Brian said, though, it should be AC, not DC, meaning the polarity would alternate.

Actually, the polarity might not alternate, but it still should be some sort of alternating square wave.

slvrbullit · 07-25-2006, 10:05 AM

Did you by the plug and play harness for the MSD or did you splice the wires into the factory harness? If I remember correctly, the white wire from the MSD is the trigger wire for the tach signal that picks up off the trigger wire for the ECC. If there is a good connection there then you may need to take the MSD back to the seller and swap it out for a new one. If you got it at SECO they should be able to test it for you. I know they did on mine when the MSD went bad and was sparking when it wanted to.

EZMachN · 07-25-2006, 10:33 AM

It was in the car when I got it. I'll check the white wire when I get home in a couple hours.

07-24-2006, 10:49 PM	#11
TheJeanyus Administrator Join Date: Dec 2004 Location: Huntsville, AL Posts: 14,774	Re: Tach problem If you hook up the voltmeter backwards, the signal will be negative. If you had hooked it up the other way, it should have been positive. Like Brian said, though, it should be AC, not DC, meaning the polarity would alternate. __________________ 1998 Mustang GT Coupe - World's Slowest Racecar 2005 Toyota 4Runner SR5 V8 2013 Volkswagen Jetta Sportwagen TDI

07-25-2006, 10:05 AM	#13
slvrbullit Super Moderator Join Date: Dec 2004 Location: on the water Posts: 1,280	Re: Tach problem Did you by the plug and play harness for the MSD or did you splice the wires into the factory harness? If I remember correctly, the white wire from the MSD is the trigger wire for the tach signal that picks up off the trigger wire for the ECC. If there is a good connection there then you may need to take the MSD back to the seller and swap it out for a new one. If you got it at SECO they should be able to test it for you. I know they did on mine when the MSD went bad and was sparking when it wanted to.

07-25-2006, 10:33 AM	#14
EZMachN Senior Member Join Date: Mar 2005 Posts: 515	Re: Tach problem It was in the car when I got it. I'll check the white wire when I get home in a couple hours.