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1999 3800 SC, Temperature Sender/Sensor & Engine Coolant Temperature (ECT) Sensor by hdryder
Started on: 10-27-2015 08:47 PM
Replies: 6 (260 views)
Last post by: Dennis LaGrua on 06-14-2021 10:19 AM
hdryder
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Report this Post10-27-2015 08:47 PM Click Here to See the Profile for hdryderClick Here to Email hdryderSend a Private Message to hdryderEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a '88 GT with a 3800 SC Series II from a '99 Regal GS donor car. It is an older swap, 10 years or more, that I purchased last year. The swap builder also installed the '99 Regal gauge cluster, which looked very bad, so I am replacing it with stock Fiero gauges.

I am trying to get the Temperature gauge working correctly. I am thinking the '99 3800 SC engine may use both a Temperature Sender/Sensor for the gauge, & Engine Coolant Temperature (ECT) Sensor for the ECM.
The only sensor that I have found so far is on the rear (trans. end) lower left (bulkhead side) area of the intake manifold, that has a Green, Black & Yellow wire harness connected to it. It is a round 3-Pin sensor.

Does anyone have photos of these two sensor locations for the Series II 3800 available that you can share?

Thank you for the help on this one.

[This message has been edited by hdryder (edited 10-28-2015).]

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Dennis LaGrua
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Report this Post10-27-2015 09:36 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
GM makes a three pin ECT sensor that also provides a gauge output. Some 3800's use them and others do not but both sit in the same spot and have the same threads. The ECT sensor sits in the location at the front top side of the engine block near the transmission. One pin is for ground, the other feeds the PCM and the center pin drives the temperature gauge. If you currently have a temperature gauge just pick up the center wire from the ECT and route it to the Fiero gauge.

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hdryder
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Report this Post10-28-2015 05:31 PM Click Here to See the Profile for hdryderClick Here to Email hdryderSend a Private Message to hdryderEdit/Delete MessageReply w/QuoteDirect Link to This Post
Dennis, thank you for that info. That works out well for what I just found on my car with the '99 3800 swap.

The Engine Coolant Temp. (ECT) Sensor I found is actually a round 3-pin connector with a short 3-wire harness that connects into a 2-wire sub-harness on the engine harness. The short 3-wire harness has a Black, Yellow & Green wires. The 2-wires it plugs into are just the Black & Yellow. Also the Fiero engine harness at the C500 connector have all been trimmed off and sealed, but leaving several inches on each wire, so I plan to run the Green (ECT) Sensor wire to the C500 connector C2 Dk Grn/Yel wire which feeds the Temp. Gauge.

What I would like to know now is what kind of input do I need for the C500 connector D3 Dk Grn wire for operation of the "HOT" Temp Warning Ind. Lamp?
Do you think that same Green wire from the (ECT) Sensor can feed the D3 "HOT" Temp. Warning Ind. Lamp?

Thank you again for the help on this one.
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Dave E Bouy
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Report this Post10-28-2015 05:39 PM Click Here to See the Profile for Dave E BouyClick Here to Email Dave E BouySend a Private Message to Dave E BouyEdit/Delete MessageReply w/QuoteDirect Link to This Post
The ENGINE HOT signal comes from the ecm. Not sure which pin on the ecm. I suppose it will vary with which ecm you are using.

DF
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hdryder
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Report this Post10-28-2015 06:15 PM Click Here to See the Profile for hdryderClick Here to Email hdryderSend a Private Message to hdryderEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dave E Bouy:

The ENGINE HOT signal comes from the ecm. Not sure which pin on the ecm. I suppose it will vary with which ecm you are using.

DF


Dave, thank you. I will check that out for the '99 Regal GS ECM used for the swap.
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longjonsilver
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Report this Post06-08-2021 07:52 PM Click Here to See the Profile for longjonsilverClick Here to visit longjonsilver's HomePageClick Here to Email longjonsilverSend a Private Message to longjonsilverEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:

GM makes a three pin ECT sensor that also provides a gauge output. Some 3800's use them and others do not but both sit in the same spot and have the same threads. The ECT sensor sits in the location at the front top side of the engine block near the transmission. One pin is for ground, the other feeds the PCM and the center pin drives the temperature gauge. If you currently have a temperature gauge just pick up the center wire from the ECT and route it to the Fiero gauge.



Thanks Dennis, on my new swap, a 2002 GTP into an 84 MT the temp needle disappears up above the gage. As the engine heats up to operating temp i get 45C on the gage (should read 90C) When i shut of the car the temp stays near 45C but when i restart the car the needle disappears again.

jon

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Astronomy says we will find a coded signal from outer space. Then we'll KNOW that life exists there, for coded signals aren't by chance.

Biology says there are coded genetic signals in every cell, but we KNOW that no intelligence created life.

I'm the original owner of a white ' 84 2M4 purchased Dec 10, 1983 from Pontiac. Always garaged, no rust, 3800SC, 4-wheel drifts are fun!

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Dennis LaGrua
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Report this Post06-14-2021 10:19 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by longjonsilver:


Thanks Dennis, on my new swap, a 2002 GTP into an 84 MT the temp needle disappears up above the gage. As the engine heats up to operating temp i get 45C on the gauge (should read 90C) When i shut of the car the temp stays near 45C but when i restart the car the needle disappears again.

jon

Make sure that the center pin of the sensor goes to the temperature gauge. Could also be a wiring or gauge problem.
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