MAT SENSOR BLUES
02-03-2010, 07:47 PM
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Car: Corvette
Engine: 388 HSR custom Cam see sig
Transmission: 700R4
Axle/Gears: D44 3:45
MAT SENSOR BLUES
Converted from CFI to HSR. Using EBL/FLASH with multiport upgrade
Upon start up I got a Code 23.. MAT Sensor. I'm using the coolant style MAT sensor from a early 90's vette.
I did some searches on here and saw the number one problem is no voltage.
This is what I've done
At the plug connector of the sensor with the "key on" I get 6.5 volts
MAT sensor at room temparture It reads 3.78 ohms on the 20K scale of the DVM.
Where do I go from here?
Could outside air temperature play a part in getting the cold? Our temps have been between 0-30 degrees for the past few weeks and I heat the garage when I'm in there with a kerosene heater
Upon start up I got a Code 23.. MAT Sensor. I'm using the coolant style MAT sensor from a early 90's vette.
I did some searches on here and saw the number one problem is no voltage.
This is what I've done
At the plug connector of the sensor with the "key on" I get 6.5 volts
MAT sensor at room temparture It reads 3.78 ohms on the 20K scale of the DVM.
Where do I go from here?
Could outside air temperature play a part in getting the cold? Our temps have been between 0-30 degrees for the past few weeks and I heat the garage when I'm in there with a kerosene heater
02-03-2010, 08:45 PM
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Re: MAT SENSOR BLUES
Malfunction 23 is MAT sensor low. Which is like the sensor is unplugged from the harness.
At key-on, engine-off, sensor unplugged. The connector should be engine ground on one pin, and +5.0 volts on the other pin. Which pin doesn't matter.
The +5 volts is from the ECM, pin C12. This is the signal back to the ECM, and will vary in voltage when the sensor is connected. The ground pin to the sensor is usually local to the harness at the engine. Usually picked up with the TPS ground or the CTS ground, then to the engine block.
The 3.78 (K) ohms on the 20K scale at room temperature is OK.
RBob.
At key-on, engine-off, sensor unplugged. The connector should be engine ground on one pin, and +5.0 volts on the other pin. Which pin doesn't matter.
The +5 volts is from the ECM, pin C12. This is the signal back to the ECM, and will vary in voltage when the sensor is connected. The ground pin to the sensor is usually local to the harness at the engine. Usually picked up with the TPS ground or the CTS ground, then to the engine block.
The 3.78 (K) ohms on the 20K scale at room temperature is OK.
RBob.
02-03-2010, 09:09 PM
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Re: MAT SENSOR BLUES
That is how I tested the voltage. Sensor unplugged one pin was 6.5 volts and the other 0 (ground). So if I'm getting the voltage and my sensor is ok. What should I be looking for next?
02-04-2010, 07:27 AM
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Re: MAT SENSOR BLUES
RBob.
02-04-2010, 08:32 AM
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Re: MAT SENSOR BLUES
Ok, I will double check this weekend.
My Air Divert Solenoid gets connected to ECM black 21. I remember going through this and was careful but who knows anything is possible. Maybe it will be a good idea as well for me to check the voltage there while the sensor is unplugged as well.
My Air Divert Solenoid gets connected to ECM black 21. I remember going through this and was careful but who knows anything is possible. Maybe it will be a good idea as well for me to check the voltage there while the sensor is unplugged as well.
02-05-2010, 12:20 PM
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Re: MAT SENSOR BLUES
Here's where I'm at an right now I'm even more confused.
According to my FSM wiring diagram
Air Divert Solenoid control
Pink/with Black strip goes to black 16
Actually a black wire was in that slot (Black 16)
That wire is now connected to Black 21, I did verify that the black wire is indeed the wire at the MAT plug location through a conductivity check.
Actually voltage readings at harness plug end
Pink/blk strip is 11.89 volts to ground
Black wire to ground is 5.04 volts
Between the two I get 6.5 volts
My thought is I need to disconnect my pink/blk strip and cap it off, then connect the other side of my MAT sensor plug to ground. Is that correct?
According to my FSM wiring diagram
Air Divert Solenoid control
Pink/with Black strip goes to black 16
Actually a black wire was in that slot (Black 16)
That wire is now connected to Black 21, I did verify that the black wire is indeed the wire at the MAT plug location through a conductivity check.
Actually voltage readings at harness plug end
Pink/blk strip is 11.89 volts to ground
Black wire to ground is 5.04 volts
Between the two I get 6.5 volts
My thought is I need to disconnect my pink/blk strip and cap it off, then connect the other side of my MAT sensor plug to ground. Is that correct?
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