Tachometer Resister

[SCJax2018]

I have a tachometer flaking out. Done took it out of the dash and tightened up the screws like most of the YouTube videos say and it still does it, just not as bad. A person said in the comments of one of the videos that there is a resister taped to a blue wire in the wiring harness near the ignition coil. My coil is in the distributor, but I do have a blue wire in the harness connection to the distributor and I undid the tape and plastic split tube and followed the wire back for a ways and didn't find any resister.  Does anyone know where this resister thing is at?

[colinnwn]

Is this person talking about the ignition condenser?

I have a VQ. I couldn't find it documented anywhere except in the part catalog, but I found it on mine. It is taped up and looks like a tiny black automotive relay. I could show you, but it is probably in an entirely different place on the VG.

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[SCJax2018]

The guy said it was a resister taped to the wiring harness near the ignition coil, but my ignition coil is inside the distributor. Like I said, I undid the tape and plastic split tube and followed the wiring harness backwards to the T it makes and saw no sign of any kind of a resistor.

 

[SCJax2018]

Could this conglomeration be my mystery resister? It is near the distributor and does look somewhat like a small relay through the tape.

[colinnwn]

Yeah that's what the ignition condenser looks like on a Nissan.

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[SCJax2018]

How would that effect the tachometer? That also looks a lot bigger than 2200 ohm.

 

[colinnwn]

When the coil field collapses most of that arching high voltage energy goes to the spark plugs, but some of it rings back onto the DC input side of the coil.

 

The condenser, which is generally a capacitor, but perhaps Nissan used a combination of a capacitor and a resistor, dampens that ring back.

 

If it isn't dampened, it can do bad things to other electronic devices, especially hall effect RPM sensors if that is what the VG uses.

 

I'm sure it is in a substantially bigger case than necessary. But you can't base a resistor size on its ohm resistance. It will have a power dissipation factor too. At 2200ohms, a tiny resistor for a tiny load might be 1/8 watt, or one as big as your fist in an industrial application might be for a 100 watt load.

 

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