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PolarBear · 05-08-2017, 08:22 PM

I finished the swap of the 4.8 into the firebird and my Tach isn't working. Engine is from a 2001 Pickup.

Outside of being connected into the wrong location in the ECM or the C100 in the 92s harness, how can I tell whether I am actually getting output from that wire? I had a 1000 ohm 1/2 watt resistor on the back of the cluster from the +12 pin to the tach input and I got nothing and the Tach output resolution - high and low, in HPT, were both set to 3 and I still got nothing. I pulled the resistor and tried changing that value to a 5, but still nothing. Next I will try putting the resistor back on the circuit board with the 5 set and see if I get something, and I will double check my pinouts

Can I use a logic probe to test the output on that pin from the ECM to see if I am getting output?

05-08-2017, 08:22 PM	#1
PolarBear Ebearnezer Scrooge/Power Member/Lips Join Date: May 2006 Location: Hamilton, Mercer county Posts: 4,141 iTrader: (16)	Tach troubleshhooting I finished the swap of the 4.8 into the firebird and my Tach isn't working. Engine is from a 2001 Pickup. Outside of being connected into the wrong location in the ECM or the C100 in the 92s harness, how can I tell whether I am actually getting output from that wire? I had a 1000 ohm 1/2 watt resistor on the back of the cluster from the +12 pin to the tach input and I got nothing and the Tach output resolution - high and low, in HPT, were both set to 3 and I still got nothing. I pulled the resistor and tried changing that value to a 5, but still nothing. Next I will try putting the resistor back on the circuit board with the 5 set and see if I get something, and I will double check my pinouts Can I use a logic probe to test the output on that pin from the ECM to see if I am getting output?