420A ECT sender wiring & idle fluctuation issue

[Dumplings]

Hello, I have a 1999 Mitsubishi Eclipse GS. It is a 420A engine and pretty much completely stock. I am having some trouble to get the engine running properly. I have two issues that I need help with and I would love any feedback you guys have.

The first issue is when in idling in any gear, the rpms start to fluctuate from 1000 to 500. I did some research on my own and followed some threads already and I am still have the same issue. I already replaced the idle air control valve, the throttle position sensor, fuel pump, and an 02 sensor. Pretty much anything to do with the air/fuel ratios. I did some more research and found out that the camshaft position sensor could also be the cause. I haven't replaced that one yet, but I did take it off a while back and put it back on with no new gasket. When I got the car, the previous owner deleted the air box and put an after market air filter. Im not sure of the car came with a MAF sensor or not and I cannot find any loose connector around that area.

The second but kind of a minor one, is that my ECT temp sensor sender has no wire to it and has been cut off by the previous owner. I can rewire the sensor on my own, but I am having trouble trying to find a good wiring diagram to trace where the wire goes to within the ECM. If anyone knows the specific pin number that would be a very great help, if anyone has an actual good wiring diagram that would help as well.

Any advice would be greatly appreciated. Thank you

 

[luv2rallye]

Did you already rule out an air leak in the air intake system? Hose connections to throttle body (TB), gaskets in/out of TB, shaft seals of TB, gasket to intake mani? You can spray WD40 on these areas while running to see if rpm drops.

ECT temp sensor positive goes to PCM (aka ECM) pin 26, and negative goes to J/C(3) pin 4 but that ends up going to PCM pin 43 (along with other sensors negatives). Do not connect the negative to chassis ground or you may experience noise on that line. It must be connected to ground within the PCM's pin 43.

 

[Dumplings]

Did you already rule out an air leak in the air intake system? Hose connections to throttle body (TB), gaskets in/out of TB, shaft seals of TB, gasket to intake mani? You can spray WD40 on these areas while running to see if rpm drops.

ECT temp sensor positive goes to PCM (aka ECM) pin 26, and negative goes to J/C(3) pin 4 but that ends up going to PCM pin 43 (along with other sensors negatives). Do not connect the negative to chassis ground or you may experience noise on that line. It must be connected to ground within the PCM's pin 43.

I haven’t tried to see if there was an air leak, I will definitely try that. Thank you very much

The one with the two wires are fine, that one works perfectly, but below it there is a one wire temp sender that displays on the dash to read the coolant level, that’s the one that isn’t working. I should have posted a picture of it, that’s my bad. When i have the chance ill
post a picture to this thread so you can see it

 

[luv2rallye]

The one wire ECT temp sensor does not go to the PCM at all. It only goes to the dash temp gauge (and the sensor's housing is the ground connection). It was a red/yellow wire that connected to the gauge cluster's C-06 connector pin 2 (to help identify the pin: C-06 connector's pin 1 has a black wire, 3 has a yellow, 4 has black/yellow, 6 has a green/white, 10 has black/white). If you find the temp sensor wire and ground it, the temp gauge should read full (after a minute).

 

[Dumplings]

Wow that is really helpful. thank you so much. when i get the chance ill take a look at it and try to fix it. i’ll lyk how it goes. thank you

 

[Dumplings]

Hello, I unfortunately have not been able to look at my car yet, but I have been thinking about the air leak. I forgot to mention that i also replaced the EGR valve on it as well. When i replaced it I noticed that there was only 1 bolt securing the pipe going into the intake. the pipe on these don’t actually go inside the manifold but is secured fastened to it, would the missing bolt be a cause of this issue that I am having? I didn’t think it would but i’m second guessing now . Any info helps. Thank you

 

[Dumplings]

Hello, this thread has been dry but I have been following the same issue with the coolant temp gauge not working. I took out my gauge cluster and i found these wires sticking out. Is this a normal part of the gauge cluster?

I’ve seen other gauge clusters and I don’t see these wires sticking out. Any information helps out. Thank you

You must be logged in to view this image or video.

 

[steve]

I took out my gauge cluster and i found these wires sticking out. Is this a normal part of the gauge cluster?

I’ve seen other gauge clusters and I don’t see these wires sticking out. Any information helps out. Thank you

You must be logged in to view this image or video.

Normal? No, it looks like a P.O. installed what used to be called Indiglo gauge faces. They require power to light up.
This was a thing back in the early aughts so most of the install links has timed out. This is missing most of the pictures.

White Face Indiglo Gauge Installation How-to - 2nd Gen. DSM

 

[Dumplings]

that’s interesting. So it doesn’t have anything to do with my temp gauge not working?

 

[steve]

that’s interesting. So it doesn’t have anything to do with my temp gauge not working?

It might by way of damaging the gauge when it was installed or over time.

 

[Dumplings]

It might by way of damaging the gauge when it was installed or over time.

ok sounds good, i’ll remove it and see if it fixes anything

 

[Dumplings]

The one wire ECT temp sensor does not go to the PCM at all. It only goes to the dash temp gauge (and the sensor's housing is the ground connection). It was a red/yellow wire that connected to the gauge cluster's C-06 connector pin 2 (to help identify the pin: C-06 connector's pin 1 has a black wire, 3 has a yellow, 4 has black/yellow, 6 has a green/white, 10 has black/white). If you find the temp sensor wire and ground it, the temp gauge should read full (after a minute).

Hello, I am really sorry to bother you guys again but I am really stuck. I was trying to follow up on this advice and I'm kind of confused. As shown in the pics, I have the single wire temp gauge, (that is yellow and red, also in the pictures). I’m trying to trace it to the connectors that go to the gauge cluster but i don’t see a red and yellow wire. Am I at the wrong connector? Am I doing something wrong?

Please help me. Thank you

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[steve]

Are there two or three connectors in the dash for your gauge cluster? I'm expecting 3. I'll try to find a picture that shows all of them and number which connector is which.

I don't have FSM for the 99 but the earlier 2GNT diagram shows this for the Coolant Temp gauge.

You must be logged in to view this image or video.

 

[Dumplings]

Are there two or three connectors in the dash for your gauge cluster? I'm expecting 3. I'll try to find a picture that shows all of them and number which connector is which.

I don't have FSM for the 99 but the earlier 2GNT diagram shows this for the Coolant Temp gauge.

You must be logged in to view this image or video.

I do have three connectors but i didn’t think the one on the far right would matter since its not near the coolant gauge. Is the wire i’m looking for in the third connector?

I’ll follow the schematic and see if that leads anywhere. thank you

 

[Dumplings]

I do have three connectors but i didn’t think the one on the far right would matter since its not near the coolant gauge. Is the wire i’m looking for in the third connector?

I’ll follow the schematic and see if that leads anywhere. thank you

Is the T/GA the ground that goes to the coolant neck?

Also earlier in the thread someone said that it was within the C-O6 connector. I don’t see the color wire that goes to that connector. Am I supposed to be looking at the A-96 connector?

Where is the C-22 connector at, because it shows it in the wire with the red and yellow and is that like a splice point I also have to look at?

I’m sorry if these are obvious questions. I’m completely new to DSMs and the Eclipse in general.

 

[steve]

The Coolant Temp Gauge in on C-06 pin 2. That is the right most connector in the dash for the cluster.

You must be logged in to view this image or video.

The temp sensor is grounded by the thermostat housing. The temp gauge in the cluster is grounded by C-06 pin 1. And power for the gauge via C-06 pin 10 from Fuse #8 in the junction block.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

 

[Dumplings]

The Coolant Temp Gauge in on C-06 pin 2. That is the right most connector in the dash for the cluster.

You must be logged in to view this image or video.

The temp sensor is grounded by the thermostat housing. The temp gauge in the cluster is grounded by C-06 pin 1. And power for the gauge via C-06 pin 10 from Fuse #8 in the junction block.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

oh ok got it got it, I would have never guessed that the one on the far right is used for the coolant gauge, I’ll reword the red and yellow wire and I’ll see if that fixes anything

Thank you for you help, I greatly appreciate it

 

[steve]

I would have never guessed that the one on the far right is used for the coolant gauge.

Note where the Engine Coolant Temp gauge is on a turbo cluster.

You must be logged in to view this image or video.

 

[Dumplings]

Note where the Engine Coolant Temp gauge is on a turbo cluster.

You must be logged in to view this image or video.

mine isn’t a turbo though, mine us a 420A and is pretty much stock

 

[steve]

mine isn’t a turbo though, mine us a 420A and is pretty much stock

I know, but guess which of the two had precedence when it came to deciding how to wire the dash. That's what I was pointing out.

 

[Dumplings]

I know, but guess which of the two had precedence when it came to deciding how to wire the dash. That's what I was pointing out.

ohhhh ok, yeah that makes more sense. thanks for letting me know