1998 240sx tach signal not right - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

hashim · 02-08-2015, 10:10 AM

Car has a zenki sr20det motor, the tach was working then stopped after I removed some spliced in wiring to the dimmer harness and main m71 connector power wire that was wrapped up and tucked under the dash. I used the fsm to trouble shoot the tach signal and I have power/ ground at the m71/m72 plug per the fsm pin 14 and 40. Checked ground from pin 40 to chassis ground that was fine also. The problem is I have 8.3 volts at the m71 pin 17 terminal, at the pin 7 on the ecu and pin 26 on the f3 with the car not running and also when it is, the car should not have any voltage there not running and when it is it should change with rpms. The fsm says the voltage should increase/decrease with rpms but it stays steady at 8.3 volts no matter what. I have an aem v2 that show rpms on the laptop but nothing on the tach itself. I swapped tachs and still nothing, everything else is fine. I'm curious if anyone has suggestions?

*dbeiler* · 02-08-2015, 01:24 PM

Sooo.......... reinstall the wire you removed.

hashim · 02-08-2015, 01:46 PM

I tried that already no luck thanks for the suggestion.

*dbeiler* · 02-08-2015, 02:09 PM

But if it stopped working when the wire was removed, and still isn't working, it most likely wasn't reinstalled properly. You didn't use one of these crappy splices, did you? It should be illegal to sell these splices.

hashim · 02-08-2015, 04:02 PM

No it was soldered in, regardless it's not working anymore. I hooked up my laptop to the aem and it is reading rpms.....so there must be a break or ground I'm thinking that's the issue, I have 8.3 Volts at the tach but it doesn't go up or down with revs. Sits constant.

02-08-2015, 10:10 AM	#1
hashim Leaky Injector Join Date: Oct 2008 Location: Montana Age: 38 Posts: 101 Trader Rating: (0) Feedback Score: 0 reviews	1998 240sx tach signal not right Car has a zenki sr20det motor, the tach was working then stopped after I removed some spliced in wiring to the dimmer harness and main m71 connector power wire that was wrapped up and tucked under the dash. I used the fsm to trouble shoot the tach signal and I have power/ ground at the m71/m72 plug per the fsm pin 14 and 40. Checked ground from pin 40 to chassis ground that was fine also. The problem is I have 8.3 volts at the m71 pin 17 terminal, at the pin 7 on the ecu and pin 26 on the f3 with the car not running and also when it is, the car should not have any voltage there not running and when it is it should change with rpms. The fsm says the voltage should increase/decrease with rpms but it stays steady at 8.3 volts no matter what. I have an aem v2 that show rpms on the laptop but nothing on the tach itself. I swapped tachs and still nothing, everything else is fine. I'm curious if anyone has suggestions?

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02-08-2015, 01:24 PM	#2
dbeiler Premium Member Join Date: Jun 2012 Location: Lancaster county, PA Age: 30 Posts: 465 Trader Rating: (4) Feedback Score: 4 reviews	Sooo.......... reinstall the wire you removed.

02-08-2015, 01:46 PM	#3
hashim Leaky Injector Join Date: Oct 2008 Location: Montana Age: 38 Posts: 101 Trader Rating: (0) Feedback Score: 0 reviews	I tried that already no luck thanks for the suggestion.

02-08-2015, 02:09 PM	#4
dbeiler Premium Member Join Date: Jun 2012 Location: Lancaster county, PA Age: 30 Posts: 465 Trader Rating: (4) Feedback Score: 4 reviews	But if it stopped working when the wire was removed, and still isn't working, it most likely wasn't reinstalled properly. You didn't use one of these crappy splices, did you? It should be illegal to sell these splices.

02-08-2015, 04:02 PM	#5
hashim Leaky Injector Join Date: Oct 2008 Location: Montana Age: 38 Posts: 101 Trader Rating: (0) Feedback Score: 0 reviews	No it was soldered in, regardless it's not working anymore. I hooked up my laptop to the aem and it is reading rpms.....so there must be a break or ground I'm thinking that's the issue, I have 8.3 Volts at the tach but it doesn't go up or down with revs. Sits constant.