WTK: B14 tachometer problem

volcanosnowstorm · Postby **volcanosnowstorm** » February 18th, 2011, 6:45 pm

Nissan Sunny 1997 (B14) A/T

I started having a problem with my tachometer about a month ago at least. The needle fluctuates erratically, but still responds (increasing/decreasing) with engine revs. On idle it adds 1500 to 2500 rpm to what it should be (still with fluctuations). I've tried disconnecting what I thought was the speed sensor and the crankshaft sensor (was trying to see if there was a loose connection somewhere) but with anything I disconnected, tachometer responded the same way (still fluctuating and moving with engine revs)

I tried using the FSM to locate the sensors, but I could be wrong. I've attached pictures of the sensors I tried. The speed sensor pics are not from my car, just found them online, identical to the one on my transmission. The Crankshaft sensor is a pic that I took (sorry about the quality if you need a better pic let me know and I'll get one).

Anyone have any ideas?

THE SYNDICATE · Postby **THE SYNDICATE** » February 20th, 2011, 7:28 am

sounds like if ur cluster is giving some problems and not any sensors!

volcanosnowstorm · Postby **volcanosnowstorm** » February 20th, 2011, 7:49 am

@Syndicate You mean the instrument panel itself?

THE SYNDICATE · Postby **THE SYNDICATE** » February 20th, 2011, 7:57 am

^^yes!

i can be wrong,but it will help, if u get another just to try out! process of elimination will help u greatly in solving this issue!

volcanosnowstorm · Postby **volcanosnowstorm** » February 20th, 2011, 8:13 am

Well, tbh, it's not the first time I heard that it's probably the cluster. I'll try to get my hands on one.

demented · Postby **demented** » February 24th, 2011, 9:35 pm

the tach signal comes from the ecu via the distributor, not from the crankshaft sensor or speedo sensor. Your problem is a common problem with B14s instrument panels...just swap the panel with another of the same type.

On the distributor, you'll find a smaller jack with 2 wires. The thicker wire is Ignition +ve and the smaller wire goes through a resistor (rectangular plastic taped to the harness right there), then to the ecu.

volcanosnowstorm · Postby **volcanosnowstorm** » February 24th, 2011, 9:59 pm

Thanks for the info man. I really appreciate the explanation. I assumed it was the speed sensor because it was the only obvious sensor in the attached diagram, and then I tried the crankshaft sensor because this wikipedia article (http://en.wikipedia.org/wiki/Tachometer) said this "the signal for the tachometer is usually generated from an ECU which derives the information from either the crankshaft or camshaft speed sensor." Working on getting a panel though.

demented · Postby **demented** » February 24th, 2011, 10:13 pm

ok your diagram is correct, you just read it wrong. You see the blue with orange stripe wire at point 29 (L/OR), this is the tach signal wire from the ECU. I think in the B14s here the wire is blue with black stripe....or could be blue with orange stripe..can't remember offhand. If you from south Hott Wheels Car Imports has panels 797-4500.