Does anybody know which dash instruments are wired through the ECM module.

Reason for question is that I'm planning a new engine, that will use a seperate unique engine control computer, and I need to figure out wiring details for the swap.

Thanks.

The check engine light and the upshift lights do need an ecm signal.
As far as the rest of the guages....they work fine without an ECM (ran carb for a year without an ecm).

None of them. All Fiero gauges read directly from their respective sending units. You don't even need the ECM if you are running a carb.

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1986 SE 350 V8

Thanks guys for the confirmation !

In some cases you can drive the speedo with a ECM, but otherwise you only need an ecu for dash lights.

So the wires that run from the various sensors on the engine (water temp and oil pressure) don't actually go into the ECM? I'm trimming down the harness for a V8 swap, with a carb, and was going to hook the ECM back up. If I don't use the ECM, then the sensor wires won't go anywhere. The wires terminate at the ECM plug now, so if I don't hook up the ECM, where do the various sensor wires go?

thanks,
Rick

The temp sender has a separate feed to the gauge and the ecm so no you don't need it.

Yes it does light the Check engine and upshift...but none of the traditional analog measurements go through the ecm.

quote Originally posted by couldahadaV8: So the wires that run from the various sensors on the engine (water temp and oil pressure) don't actually go into the ECM? I'm trimming down the harness for a V8 swap, with a carb, and was going to hook the ECM back up. If I don't use the ECM, then the sensor wires won't go anywhere. The wires terminate at the ECM plug now, so if I don't hook up the ECM, where do the various sensor wires go? thanks, Rick

the C203 connector - its the 15pin connector near the ECM where the wires go thru the firewall, under center console.
as mentioned above - the shift light & the "Check Engine" light are the only things on the dash which have ECM input.

quote Originally posted by couldahadaV8: So the wires that run from the various sensors on the engine (water temp and oil pressure) don't actually go into the ECM? I'm trimming down the harness for a V8 swap, with a carb, and was going to hook the ECM back up. If I don't use the ECM, then the sensor wires won't go anywhere. The wires terminate at the ECM plug now, so if I don't hook up the ECM, where do the various sensor wires go? thanks, Rick

The easy way to do the carb wiring is remove all wires that connect to the ECM connectors (you will keep the 203 and 500 connectors, but none of the ECM ones). You will be left with starter, alt, A/C, ignition/dist, temp sender, fan thermal switch, oil pressure sender, VSS, A/C and fuel pump relays.... and a pile of other wires that are not needed.