Ls mechanical guage questions

[Ta2edjr]

I know there is a couple threads on this but most are very unclear in my opinion. I have a couple questions and a couple solutions. Let me know what ya think.

First off coolant temp sensor.
There is many ways this can be done....
Here's what I think may be the easiest of all..no drilling or tapping the cyl head for a bigger sensor and not using 3 fitting screwed together to get your mechanical sensor to work... here's my theory. My stock sbc coolant temp sensor has one wire going from it to my guage. The Ls coolant temp sensor has a couple wires going from it to the ecm...is it possible to to Tee into one of those wires and take it straight from the harness to your temp guage?. Because if this can be done than this truly is the easiest way.

Oil pressure sending unit.
You can unthread this from the engine and put a fitting in its place and then run your oil line from it to your guage. My question for this is does doing away with the electronic oil pressure sender have any effect on the ecm? I've seen where people make a fitting where they have a oil feed line and electronic oil pressure sender all in one..

These are my questions and concerns any and all help is appreciated. Thanks

[ls1nova71]

You can't T into the wires going to the PCM, that would be asking for problems. The PCM needs a dedicated sensor. The 98 F bodys have a 3 wire sensor that had both the PCM and gauge wires built into one, but if you use it, it won't be accurate for a 67-72 gauge since the ohm ranges are different. As for the oil pressure, unless you have a newer engine with DOD, you wont need the electric sender.

[Ta2edjr]

Originally Posted by ls1nova71

You can't T into the wires going to the PCM, that would be asking for problems. The PCM needs a dedicated sensor. The 98 F bodys have a 3 wire sensor that had both the PCM and gauge wires built into one, but if you use it, it won't be accurate for a 67-72 gauge since the ohm ranges are different. As for the oil pressure, unless you have a newer engine with DOD, you wont need the electric sender.

Thank you for clearing this up some I didn't think about the ohms being different for the sensor...and i have a question for ya school me on what DOD is lol my ls engine is a 5.3 from a 2000 silverado so will I need to keep the factory oil pressure sensor?

[ls1nova71]

DOD is Displacement On Demand, your 2000 LM7 wont have that so you dont need the sensor.

[Ta2edjr]

Thanks for the help! Sure do appreciate it!

[BR3W CITY]

Are you on a stock reworked harness or an aftermarket? My harness had a dedicated oil pressure sensor gauge wire in it, tho i never used it.

[nsb29]

would you need the oil pressure sending unit if the DOD is turned off

[Ta2edjr]

I'm using a stock harness that I reworked myself. I have the original mechanical gauges I'm my 72 c10 and I'd like to keep them so that's why I was asking about all off this

[BR3W CITY]

To clarify, GenIII's do NOT use the oil pressure input signal to the ECM for ANY reason other than an idiot light on the dash. The PID (the address in the computer) is just a static on/off that turns on the light.

On GenIV engines, the ECM uses the oil pressure sensor as an actual #, and if monitored, the PID will display actual oil pressure. This is useful for digital gauges, scanguages, and for logging. That oil pressure sensor is also part of the DOD control and uses fluid pressure thresholds to function. With DOD deleted, this won't matter. IIRC, with DOD turned off, the sensor itself still functions as normal for logging purposes etc.

Keep in mind too guys, that an oil LEVEL sensor and an oil pressure sensor do not give you the same info. You CAN have oil pressure in an engine that qts low.

IMO I'd just tap or adapt a fitting on the oil cooler port (on the pan), and run that for your gauge. I use it for my mechanical OP gauge, just not the stock one.

[Aruba1]

I am using my stock gauges for temp and oil pressure. For Temp I bought a metric to SAE adapter on ebay. My temp probe was too long so I bought an extension at O'reilly and that gave it the extra clearance that was needed. I think the probe is about 2" long. I added the adapters to the rear of the passenger side head. No issue and no leaks so far. For the oil pressure I bought an adapter online and removed the stock oil sender unit. The pressure line hooked in it's place through the adapter and works great. Mine is a 5.3L 2001.

[Thealien]

When I did mine I kept the LS oil pressure gauge for no other reason than being able to read it with a scan tool and I also had a gauge that plugged into the OBDII port and could read it. I tried to keep as many of the factory sensors thinking I "may" someday upgrade the gauges?

[nsb29]

I have ben wondering how to use my amp gauge as the ECM regulates the alternator ?

[ls1nova71]

Originally Posted by nsb29

I have ben wondering how to use my amp gauge as the ECM regulates the alternator ?

I looked into it a long time ago, and could never find a good way to make it work. Add to that the fact that the factory ammeter isn't that good of a gauge anyway, I converted mine to a more accurate voltmeter. Member TBONE1964 makes a kit to swap it out and it's super easy and looks completely stock, basically what it would have looked like if GM had done it in 72. This is a pic of my rusty green truck in his thread. http://67-72chevytrucks.com/vboard/s...7&postcount=58

[BR3W CITY]

I've never actually found an amp or voltmeter to be too useful as a stand alone gauge. The Scanguage can check voltage if need be, otherwise its just extra information to look at.