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I have an 85 P-type with a 7MGTE swap. My temp gauge in the dash reads way hot but my after market temp gauge reads 180 or less. I disconnected all the sensors from around the thermostat housing but the gauge on the dash still is getting a reading from somewhere. Is there another sensor? Also will the ECU turn off the motor if the gauge on the dash has a false reading? Thanks.
 

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The gauge is just a gauge no connection to the ecu. There is another sensor that reports temperature to the ecu.
 

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The gauge is just a gauge no connection to the ecu. There is another sensor that reports temperature to the ecu.
Thanks. I think the temp sensor with the green and brown wires connects to the ECU. What’s weird is, when I disconnect all the sensors, there is still a reading on the gauge. Maybe a short?
 

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Did you wire it? Does it work at all, or does needle immediately go full hot? Also, 7ms have 2 single prong hookups on waterneck, 1 is gauge sensor, 1 is fan switch..are those swapped?.
 

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Did you wire it? Does it work at all, or does needle immediately go full hot? Also, 7ms have 2 single prong hookups on waterneck, 1 is gauge sensor, 1 is fan switch..are those swapped?.
I didn’t wire it. I May have accidentally switched the two. It immediately goes full hot. Thanks.
 

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It will show full hot if not connected to anything. It should be connected to the single wire temp sender on the thermostat housing (not the 2 wire sensor that goes to the ECU). The gauge sender is totally separate from the engine wiring and won't shut off the engine if reading hot.
 

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It will show full hot if not connected to anything. It should be connected to the single wire temp sender on the thermostat housing (not the 2 wire sensor that goes to the ECU). The gauge sender is totally separate from the engine wiring and won't shut off the engine if reading hot.
Outstanding information! Thanks!
 

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The water gage normally come from a single blade sensor, near/under the dizzy, side of block.
Not 100% sure the 7M is same.
 

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The water gage normally come from a single blade sensor, near/under the dizzy, side of block.
Not 100% sure the 7M is same.
On the 7M it is on the thermostat housing.
 

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Discussion Starter #15
I got the car back on the road?. There is a sensor attached to the clutch peddle that was turning the motor off intermittently ?. Thanks everyone!
 

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On the 5-MGE,there are 3 sensors for coolant.The gauge sensor in under the distributor and there are 2 more on the thermostat housing on top.The sensor that feeds the ECU and the other one tells the EGR to work/not work.A "timer" style switch.Also the cold start injector.
The right side sensor tells the ECU to change the mixture when in closed loop.Those terminals corrode like heck and will fool the ECU into making a lean or a rich fuel/air ratio and cause drive ability issues and lousy gas mileage.Yes,those Bosch connectors are brittle.NAPA has 'em.
 
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