I am going to be running an AutoMeter electric oil temperature gauge, and would like to wire it into the PCM.

I know the PCM has existing tables for oil temperature, that help regulate fan enable points and other things, so it would be nice to have control over those now.

Does anyone know which wires are used for this input? Anyone done this before?

TIA!

 

You should be able to connect to Blue connecter terminal D26. That is the sensor input. The other side of the sensor should be connected to Black connector terminal B6 which is sensor ground. I tested it on the bench with a 8051 PCM so it should work just fine, get a oil temperature sensor from a 94/95 Corvette and you will be setup to go.

The way it works is, there is 5v at D26. The oil temperature sensor is a thermistor which changes resistance with temperature, the hotter it gets the less resistance. As it gets warmer the sensor allows more current to flow through it to ground which in turn pulls the 5v reference voltage down.

The less voltage at D26 means a higher temperature that is displayed, if its an open circuit to ground which it is now in your PCM you will see a -40c temperature value, short D26 to sensor ground and you will see about 164c which is the maximum value.

 

Thanks a lot for the help!

Do you have any idea if the sender that will come with my AutoMeter gauge could be made to work? I was hoping to get double-duty out of it, rather than having to tap the pan twice, for two separate sensors!

 

That I can't tell you. But if it is as with most aftermarket gauge setups that uses a 12v ref voltage then no, it won't work. All PCM and ECM sensors relie on a 5 volt reference voltage.

But here is a bit of good news. The Corvette oil temperature sensor is a dual output. There is a second sensor that connects to a dash gauge. So perhaps you can use that second sensor with your aftermarket gauge.

The Corvette sensor uses Pin A for sensor ground, pin B for the PCM Pin D26. Pin C goes to the dash gauge and the other side of that second sensor is grounded internally to the engine ground.

 

You can mount the AutoMeter oil temp sender in the drain plug, and save having to tap the pan for the AutoMeter gauge.

See this photo

Alternatively, if the Corvette unit is a dual output, you could probably run the gauge off the +12V side, and the PCM off the +5V side.

Where is the oil temp sensor mounted on the Corvettes.... in the block or in the pan?

 

Thanks again for all the helpful input!

Fred, will I need any special fittings to mount the AM sender in the oil filler hole? I think I will start with that until I figure out what would be involved in the Vette sender.

Solomon

 

The Corvette sensor is located on the drivers side of the oil pan about 2.5 " from the bottom centered in the sump.

 

Did you set this up Solomon? How is it working? I'd like to program my fans to turn on high if the oil temp goes above 280 or so as an additional failsafe. I'm almost glad I don't know what my oil was running on a few hot days last year...I'll bet it started with the "3." I'm hoping to keep it well below that with a cooler this year but we'll see.

Thanks a bunch for the info, tjwong!

 

No Jon, I never did try the Corvette sender. Thanks for reminding me, though!

 

For anybody else interested, the Corvette sender Part #10096136 goes for around $20-25. I've come down to that part number from three different sources so far but if anybody knows different, post up! FWIW it seems to have been used by GM on numerous vehicles since 1990.

 

Anybody know if you do wire up this sensor, if the tables will become valid and use the oil temp input values to adjust timing and fan temp operation?? To make things more confusing, I have a 1996 Impala with an OBD1 conversion. I would love to use this node to monitor but do not want the PCM to use the information to make adjustments. So what will it do??

Thanks and please be nice since it is my first post,
TOM B

 

im also very interested in this. anyone have any more ideas on this? maybe i'll buy a sender and test it out sometime

 

Another quick question/request. Does anybody have the table from the FSM that shows the temp vs resistance for this sensor?? If so, could you post it or send it to me via email??

Thanks,
TOM B
Tom.Bristol@emulex.com

 

The temp vs. resistance table for 5V sutomotive thermistors is pretty standard. I have it in my ScanMaster writeup, under "CLT (coolant temperature)"

http://members.aol.com/InjuneerZZ/ScanMast.htm