NEED Wiring Whiz-two wire to three wire coolant temp sensor

[TheDirtyBen]

94 achieva is getting a 2002 3100. new motor has a 3 wire coolant temp sensor instead of two temp sensors. old harness has a green wire for the single-wire sensor, and brown & yellow wires for the two-wire sensor. new harness has black, grey, and red w/black stripe. what wires should i match up?[/img]

[korbendallas68]

This is quoted from my newely revised 3400 Guide 2.5:


Installation:
You will need a deep well socket size 19mm to get the sensor out, and to install it.
- Remove the air box assembly
- Remove the throttle body
- Un-hook the connector from the sensor
- Using the deep well socket, remove the sensor. There will be some coolant that will spill out! But not a lot, so just wipe up the mess.
- Install the sensor
- Now to hook-up the sensor, you will have to visit a junkyard and get the correct 3-pin connector. It's the same connector that is used on the throttle position sensor. Check out the diagram for the sensor for the pin locations
Pin A = Black, PCM Sensor GROUND
Pin B = Yellow, Coolant Signal to PCM
Pin C = Dark Green, To Dash
- Splice into the correct wires
- All done!

After Installing:
Now one thing that you may have noticed when you have the sensor installed, and have had the car running for a good amount of time (to get it to normal operating temp), is that the temp on your dash reads different than it did before! What?s going on you ask? Is the sensor faulty, or did I give you some bad info? Nope. If there is a problem with the temp gauge at all, it is certainly not that it is inaccurate. The gauge is perfectly accurate (well I assume it would be...), but the sending unit for the dash is mounted in the wrong place to get a 'correct' reading. Unfortunately there are no other tapped holes in the heads to mount it, unless you tap them yourself. It should be good enough to give you an accurate reading anyways.


Your welcome!


-Ryan

PS: If you need the newer verison of the guide, it will be out soon!

[geoffinbc]

Or take A&B wires from old connector and splice into A&B on the new connector. Take your remaining single wire and splice it into C location.

That thing said it gives the wrong reading but that is crap. GM released a bulliten at one time because customers complained of weird readings from the sensor in the head. So they released this bulliten recommending the replacement of the 2 wire sensor with a 3 wire sensor so it fed the ECM and guage all from the same spot. The spot by the thermostat is just as accurate as the one in the head. Hey if the ECM runs of of it then I would think it would be the most suitable spot.

The difference in the guage can be explained by the fact that the old one was wrong and the new one is more likley to be right. Oh and when Lloyd and I did the swap there was no difference.

[korbendallas68]

So it's not true that the temp is wrong? It seems to be on my car... But every thing is pretty much brand new, engine / coolant wise. And I don't have the A/C condenser.

[geoffinbc]

What is your guage reading? Is it about half way up the face? if so I'd say its bang on.

[korbendallas68]

Well here check for yourself.

Normally on a 94, 95 Grand Am V6, the gauge is right at the middle when engine is at temp. Mine never ever goes up that far. Not that it doesn't get that hot, it just seems like a different reading.

The red line marks the normal point that the needle usually goes. A little bit after that the fan kicks on.

[geoffinbc]

Hmm what stat is in there? Did this happen just when changing sensors or when you put in the new motor and changed the sensor? If I were you I would look into a new stat. My moms car did the same thing when her stat went. It would never get past 1/4 while driving.

What I am saying is there is no reason why the sensor in the intake would read much different than a sensor in the head.

[JohnyG]

I experience the same problem, the temp gauge usually sits about at a 1/4.

The only times I get it up to half is after a 90sec. autox run.

-John

[SappySE107]

Don't go by the gauge, its not dead on accurate for what you would think it should be. Proportional is not how it works. You really need a scan tool to check what the computer sees.

[geoffinbc]

Ageed.

[korbendallas68]

I think it's ok. The heat that blows out of the vents gets nice and warm. It's ok, I already assumed that most gauges on a dash are never accurate.