I am running a gm 3800 with the factory ecm. I want to hook up a temp gauge but the only place I can find to put the sensor there is already a factory sensor there. Will it affect the computer if I unhook this sensor?

Is it the temp sensor the ECM uses or was it for something else like a temp light? The ECM definently needs to see the engine temperature to get the fuel mixture right. Just curious what are you going to do about things like the speed sensor and the dual oxygen sensors that were on the car?

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Dodge 2.2L Turbo Power Running Megasquirt-n-Spark MPI.
http://www.woodsbuggy.com/forum/water-cooled-engines/3584?p=24592#p24592

The wiring harness that was on the motor and trans went through the firewall and hooked to the ecm. I did not mess with any of the sensors for engine control. Anything that went from the engine or trans to the ecm, I left it alone. I have ran it like that (on jack stands), seems to run good.

There is two sensors for that. One controls a light and the other controls a gauge. If the factory sensor has two wires, one will go to the ecm, the other to light or gauge. Purplerail is gm guy he may be able to look up what color goes where. You may have to change the sensor to work gauge insted of light. If he cant , I need more info on donor car and I'll get the info. I ran in to this same problem on v-8 Fiero

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"YOU CAN MAKE THINGS HAPPEN, WATCH THINGS HAPPEN OR WONDER WHAT THE F$$K HAPPEND...WE'RE MAKING THINGS HAPPEN" The strong words of Captain Phil! Rest in peice!

The donor was a 1988 olds delta 88. 3800. One sensor is near the intake at the opposite end of the motor from the pulleys, it has two wires.There is another sensor near where the water pump is( it only has one wire) that may be the other one. Which one is for the light and which one is for the ecm? I already have the harness wrapped and all sealed up, hate to unwrap it all to trace the two wires. One of them may be for starting the electric fans? they are on a toggle now.

I will reserch that. The one with two wires is the one that might need changed. Does it have a yellow and brown wire? The one with one wire is probly fan switch. It would ground the relay when fan is ready to come on.

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"YOU CAN MAKE THINGS HAPPEN, WATCH THINGS HAPPEN OR WONDER WHAT THE F$$K HAPPEND...WE'RE MAKING THINGS HAPPEN" The strong words of Captain Phil! Rest in peice!

Yes the double wire one is brown and yellow. The single one is black.So since the fans are on a toggle now, I can do away with the one wire sensor and put my gauge sensor in that spot?