Question about wiring
Veteran
Joined: Apr 2005
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RE: Question about wiring
Legend
Joined: Jul 2004
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RE: Question about wiring
All you need to do is wire the tach correctly and splice the grey wire with a black stripe comming out of the PCM to the pickup wire for the tach. You will have a fully functioning tach that reads full rpm.
Red is accesory, Black is negative, there might be a yellow, that goes to a constant power source, the other wire is the pick-up wire.
Record Breaker
Joined: Mar 2005
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RE: Question about wiring
You have a '95? If it didn't come with a tach from the factory, chances are you aren't going to get a useable (e.g. square wave) signal from the grey wire with the light blue stripe that's at pin 7 on the J2 jumper behind the instrument cluster (where everyone else gets the signal), if there's even a wire there at all... You can give it a shot, but when it doesn't work, you have 3 options.
1 - If you don't plan on using the tach like it's supposed to be used (high rpm shift points), you can rig a workable signal using diodes and resistors on the coilpack grounds using this diagram as a guideline:
That shows 2 coils, but tapping off the 2 grounds on the single coil achieves the same effect. Keep in mind, once you get above 6000 rpm or so, the tach is going to bounce around more than a narrowband a/f gauge because of dwell time overlaps. But it'll look pretty... most of the time...
2- Again, if you're doing it just to have a tach, just tap off one of the coilpack ground wires. RPM indicated on the tach will be one half of actual engine rpm. Most people will never notice.
3 - Fully functional and more accurate than the factory wiring (which is calculated off of the crankshaft sensor signal)... You need a tach driver. My preference is the MSD Distributorless Tach Driver (part # 8913) that you can find at Summit/Jegs or other parts places on-line for $70-75, or occasionally used on ebay for under $50. Easy enough to hook up, and can drive more than one unit if needed (like a shift light), which the factory connection can't... not that you'd be likely to use it anyways...
Best of luck!
1 - If you don't plan on using the tach like it's supposed to be used (high rpm shift points), you can rig a workable signal using diodes and resistors on the coilpack grounds using this diagram as a guideline:
That shows 2 coils, but tapping off the 2 grounds on the single coil achieves the same effect. Keep in mind, once you get above 6000 rpm or so, the tach is going to bounce around more than a narrowband a/f gauge because of dwell time overlaps. But it'll look pretty... most of the time...
2- Again, if you're doing it just to have a tach, just tap off one of the coilpack ground wires. RPM indicated on the tach will be one half of actual engine rpm. Most people will never notice.
3 - Fully functional and more accurate than the factory wiring (which is calculated off of the crankshaft sensor signal)... You need a tach driver. My preference is the MSD Distributorless Tach Driver (part # 8913) that you can find at Summit/Jegs or other parts places on-line for $70-75, or occasionally used on ebay for under $50. Easy enough to hook up, and can drive more than one unit if needed (like a shift light), which the factory connection can't... not that you'd be likely to use it anyways...
Best of luck!