TinkerToyII

on my 5.7 TPI i want to use aftermarket gauges and I am assuming that the Oil pressure and water temperature senders that connect to the computer need to be left alone. I want to use electric gauges and so I am anticipating I need to install sending units that will be compatible with the SW electric gauges. It appears that I can put a "T" where both the original Water Temp. sender and Oil sender are and then add a second sender to both> Are there any precautions that I should be aware of?

Thanks Randy
1992 Firebird 5.7 TPI

Drew

iTrader: (58)

Seeing as how the gauge cluster doesn't receive the engine temp or oil pressure signals from the ECM but from stand alone sensors, directly, it shouldn't be a problem. Remove the gauge senders, and leave the ECM sensors alone. The ECM only cares that there is an oil pressure switch, and on most later TPI cars the switch is built into part of the oil pressure sender for the gauge. For the water temp, the gauge sensor is in the driver's head between #1 and #3, and it only sends to the gauge.

Tibo

iTrader: (15)

The oil pressure sensor/sending unit functions as part of the fuel pump circuit as well as the gauge for the oil pressure sending unit but it has no tie in with the ECU. There are two separate coolant temp sensors, one is located on the side of the cylinder head (driver's side I believe) that feeds the coolant temp sensor gauge and there is another coolant temp sensor that supplies the ECU.
It is typically not a good idea to T off of a sensor to a second gauge.

TinkerToyII

Thank You for your fast response...

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Are you indicating that there is a separate sender for the oil pressure other than the one on the filter housing, that has three wires?? This is the one that I thought I would have to put a Tee in and add another sender...

For the water temp, the gauge sensor is in the driver's head between #1 and #3, and it only sends to the gauge. So the ECM doesn't care about water temperature? Then I could change the water temperature sensor. I connected a SW gauge directly to the Water Temperature sensor and B+ and the gauge it did not like it.

Thanks Again
Randy

Tibo

iTrader: (15)

The sensor that is on the side of the cylinder head is a one wire variety and it goes to the gauge cluster. It is self grounding so it doesn't need a separate ground wire because it doesn't have to be super accurate. The coolant temp sensor for the ECU is a two wire variety who's ground is shared with a few other sensor's. It should be located close to the thermostat housing, have two wires and it, again, feeds the ECU only.

TinkerToyII

iTrader, So if I should not put in a Tee where would I get the signal for a SW gauge, the only other place I know there is a tap for oil pressure is on the back of the block by the distributor, at least I think there is one there, I am old school...

Tibo

iTrader: (15)

There is no need to T off of a wire or add a T fitting to add two oil pressure sensors. The oil pressure sensor already has a sensor line that goes up to the gauge cluster.

TinkerToyII

I knew there was a sensor there but did not know what it was for, thanks....

Drew

iTrader: (58)

Earlier cars, like up until 87 or 88 have a oil pressure sensor for the gauge, and an oil pressure switch for the fuel pump circuit, both screwed into a tee fitting into the port behind the distributor. Later cars have a oil pressure sending unit with a built in pressure switch, screw into the port above the oil filter. A tee to run both the OE sender/switch and your aftermarket gauge sender should be fine, since that's how GM did it for several years. The other way to go, would be to replace the OE sender/switch, and run the older style switch plus your aftermarket sender. Either way you need the switch.

The ECM has it's own ECT sensor in the front of the intake. The sensor in the drivers head only runs the dash gauge.