Help with ECT sensor

[SleeperLS]

So I am trying to troubleshoot some of the last couple bugs I have before I can start driving. I fixed my air intake sensor today. I ended up ordering a GM boost friendly one and will thread it into the intake pipe post BOV, but that works. The last issue I can't figure out is the engine coolant temp sensor (ECT). The sensor worked before I pulled everything out and put it all back in.

To my knowledge there are two types of sensors from GM one is a 2 prong and one is a 3 prong. I have the 3 prong in my car as well and the wire for the 3 prong. There is a black wire, gray wire, and a red wire with a black stripe. I did the volt tester trick and one wire has the 5v reference, the other two are ground. All of these work to my knowledge because I am pretty sure the sensor is 2 grounds and a 5v per GM. I figure the sensor must be junk so I go to oreily and pick up a new one. Plug the new sensor in and set the tip of the sensor in warm water. My HPT is still picking up -38 for my ECT sensor. Since fueling is pretty much controlled by the ECT, I am kinda screwed until I figure this out.

I have a couple wire diagrams and the Haynes one shows that I should have the 2 prong ECT sensor with one yellow and one black wire. This 3.8L PCM pin printout I found a while back has been more accurate IMO with my frankenstein shit. It shows the PCM having a red wire for the ECT sensor(which matches up to my wireing at the sensor). I am thinking about just bypassing crap, but I don't know if it is even worth it since I have 5v and 2 ground to my sensor.

Any idea would be freaking huge...I am pretty lost at this point. Thanks in advance!


Edit: Can someone look on their GTP and tell me where their ECT wire harness runs to. Maybe I am using the complete wrong wire/connector. Mine runs up from underneath the exhaust near the PCM and where the AC lines should be.

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[Turbocharged400sbc]

the ect harness breaks out of the engine harness near the BBV solenoid/number 5 injector, its a 3 pins in a row connector that plugs into a 14 inch long pigtail that terminates in either a 3 pin triangle or a two pin inline that plugs into the ECT sensor below the Tstat.
from the factory the pigtail plugs into the breakout near #5 and runs along the intake passing right next to the front Tstat housing bolt then curls down to the ect.

the red grey and black connector is for your AC pressure switch/sensor that lies inboard of the drivers side unibody rail below the pcm/harness ground area, on the AC line

if you could scan the ac pressure switch you woulda seen changes...asit is your impersonating a monkey fucking a football but i wont rag on you too hard.
the fact that ect stays low the circuit is at inf resistance/open fyi shirt the pigtail and the temp goes to 250iirc

btw the threadin iat sensor is a standard SI 3800 IAT that comes in 3/8ths npt.
you would be fine however just putting the sensor and wires in front of the radiator.

get that pos running

 

[SleeperLS]

he is alive, and yes I am a jackass. haha, damnit I had a feeling it wasn't the right plug but it fits so nicely. does that same harness have a little oring type tab on it?

 

[Turbocharged400sbc]

yeah lots of connectors are similar to each other, its cheaper and they tend to put similar connectors far from each other to prevent stupidity....you can see how well that worked out

yeah a brownish tab that clips onto a small m6 stud that shicks out of the top of the smaller Tstat bolt that goes in the lower left hole

 

[SleeperLS]

haha, no shit! That AC connector fit perfect legth wise to my ECT sensor...rookies. I gotta find that damn pigtail. I looked and didn't see it, but I remember it at one time. Looks Like I am going digging through everything

Thanks for the help though man. Once I hook that up there shouldn't be any reason it doesn't run right....unless there is a huge vac leak somewhere.

EDIT: Warming up garage right meow....found pigtail

 

[Alacran]

if its a three prong sensor it should be signal, ground, and 5v. Is this the ECT to the dash?

 

[SleeperLS]

I am pretty sure what happened is that the sensor came with the manifold which is new to my car. My old manifold had a 2 prong. This one has a 3. Good news for me is I ordered a 2 prong sensor the other day, so I now have a new sensor waiting to go in. Sure enough my pigtail is 2 prong. So I am good to go. I believe you are right on those wires. One 5v, one wire goes to the PCM and the other goes to the dash. It is different for many 3800's evidently. Some are 2 and some are 3

 

[1quick]

sorry to take this off topic but what do you do to get the map sensor to work on a turbo'd na motor, do you have to get a different one or is it in the tune, just a question phatride brought up to me the other day since all the turbo cars he had done started as gtp's

 

[SleeperLS]

I actually have a gtp wire harness that was chopped up and made into a swap harness for the supercharged motor.

 

[ProjectGTP]

sorry to take this off topic but what do you do to get the map sensor to work on a turbo'd na motor, do you have to get a different one or is it in the tune, just a question phatride brought up to me the other day since all the turbo cars he had done started as gtp's

Use an L32 map sensor, which is a 2 bar map sensor.

 

[02BlueGT]

yeah lots of connectors are similar to each other, its cheaper and they tend to put similar connectors far from each other to prevent stupidity....you can see how well that worked out

yeah a brownish tab that clips onto a small m6 stud that shicks out of the top of the smaller Tstat bolt that goes in the lower left hole

Welcome Back

 

[Turbocharged400sbc]

sorry to take this off topic but what do you do to get the map sensor to work on a turbo'd na motor, do you have to get a different one or is it in the tune, just a question phatride brought up to me the other day since all the turbo cars he had done started as gtp's

Use an L32 map sensor, which is a 2 bar map sensor.

L32 or sc/tc ecotect 2 bar map sensor as stated as well as an 04+ GTP bin, make sure it isnt a compG bin
i wired al's 04 with an early map plug to use the larger l67 2 bar map so thats an option for ya

Welcome Back

i got that rvsp thingy somewhere in the garage for ya

 

[1quick]

L32 or sc/tc ecotect 2 bar map sensor as stated as well as an 04+ GTP bin, make sure it isnt a compG bin
i wired al's 04 with an early map plug to use the larger l67 2 bar map so thats an option for ya



i got that rvsp thingy somewhere in the garage for ya

do i need to get a different plug and wire it up, or is the l26 plug the same?

 

[Turbocharged400sbc]

the l26/l36 1bar map sensor uses the same plug as the L32/sc/tc 4banger 2 bar map
you would have to get a different plug to use the earlier and more readily available 2bar "big" map.
i have the osid/file for the gtp bin which should be on the dhp site and probably others

 

[1quick]

thanks for the info