using stock gauges with LS swap harness?

[paradigm]

Can I use PCM outputs to provide signal to the stock gauge cluster to get the speedometer, tachometer, oil pressure and water temperature working?

My PSI conversions harness has wires for the following:

Black - Speedometer signal from PCM. 4000 pulse per mile signal that is readable by most aftermarket speedometers.
White - Tachometer signal from PCM.
Grey - ECT Lead, Engine Coolant Temp output wire from PCM.
Tan - Oil Pressure Lead, Oil Pressure output wire from PCM.
Brown - MIL Lamp Ground, provides a ground to the “Check Engine Light” bulb from PCM

It also has these wires which aren't hooked up:
Orange - Park Neutral Signal into PCM.
Purple - Brake Signal / TCC Ground. Signal into PCM so it knows when brakes are applied, to control Torque Converter Lockup and Cruise Control.

 

[81cutlass]

Yup,

There are better videos than mine from 7yrs ago but I know the content lol.

If you have a Chev a 88-91 G van or Suburban square body you can put the speedometer in the G body dash, otherwise you need to do an aftermarket speedometer.

But yeah stock gages work with a 99-02 truck oil pressure sensor and 98 F body LS temp sensor. Tach just takes some configuration using HPT.

 

[paradigm]

Yup,

There are better videos than mine from 7yrs ago but I know the content lol.

If you have a Chev a 88-91 G van or Suburban square body you can put the speedometer in the G body dash, otherwise you need to do an aftermarket speedometer.

But yeah stock gages work with a 99-02 truck oil pressure sensor and 98 F body LS temp sensor. Tach just takes some configuration using HPT.

Thanks. I should mention that my trans is a 700r4 mechanical trans, not an electronic one. Would that work with my factory speedo?

 

[64nailhead]

Jake, how well did the oil pressure and coolant temp scale onto your factory gauges? And were you able to get the factory tach to function?

 

[81cutlass]

If you have a 700r4 that is mechanical output the factory speedometer will work fine, no fussing needed. I assumed you had a 4lx0e or t56. I have a t56. Some later 700's had an electronic output.

Oil and coolant temp scaled into the stock G body gage pack fine. The 98 Firebird LS1 coolant temp sensor runs on the same ohm range as a G body and same goes for the 99-03 truck oil pressure sender. 99+ LS went to 2 wire output so there is no 3rd wire for temp output, only 98. 04+ LS went to 5V output that reads into the ECU, 99-03 feeds direct to the dash, no hand off through the ECU. Factory tach functions great too, I just connected the output from the 02 ECU to the tach input wire on the G body wire harness and configured the tach output in HPT.

I use the OEM tach to shift and it stops at 6k and I have a shift light set to 6700ish so when it goes past the 6k line on the dash I know to pay attention to the shift light.

The oil pressure gage isn't overly accurate but it works well enough to tell me if the engine is out of oil and the coolant temp works well enough to tell me if it's overheating.