ECT sensor inaccurate

[phantom_19]

Hi

My car is a 1993 eagle talon awd. I have fought with this issue for quite some time now. I have ECMlink and my Engine coolant temp sensor reads anywhere between 34 and 200+ degrees. It jumps when i throttle the car. I have checked various online manuals like

http://www.westernsubaruclub.com/files/JeremyDSM/1g-MT-Turbo-DSM-starting-troubleshooting.pdf
to check the ECT. I read 1.56KiloOhms at 32 Celcius which is about right. I have checked if the wires on the ECT run to Pin 24 and 20 with continuity tests. What else can I do?

I havent used any teflon tape when turning in the ECT into the lower Tstat housing.
The Tstat housing has paper gasket on both connecting points. The sensor is brand new from Ebay. Do you guys think this is a grounding issue? Where would the grounding of pin24 go to on the chassis so I can double check if it's connected.

I forgot to add. Does the ECU box ground on the dash pillars when you secure it to the car? Because it has ground wires on the smallest pigtail. My ECU is just laying on the carpet while its connected

 

[phantom_19]

Hi again.
So i opened up my ECU today and looked at the back side if it. I noticed that there is a copper flake that is split in half. Between the 2 there is no continuity.
I checked using a multimeter. (the left flake does not connect with the right flake). Should they be connected and is this why my ECT sensor is inaccurate? The area above the flake is the area of the biggest pin.

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

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

 

[steve]

If I remember correctly that's a blown sensor ground on a 1G ECU. That means you had something miswired at some point and put 12v on the sensor ground from the ECU. If it's still bad you'll blow the trace again after fixing it.

 

[phantom_19]

Damn man.
I might get it fixed, but am not going to do it myself. My intake temp and coolant temp were always bouncing around when i throttled the car. This might explain why. Its not cool if I just drop a solder between the 2 copper flakes right?

I saw the post on wiki. But for the 2G it blows on a different spot. The 1G could be on a random spot. http://www.dsmlink.com/wiki/blownsensorground?s=sensor%20ground

 

[steve]

Its not cool if I just drop a solder between the 2 copper flakes right?

That would do the job but putting a drop across that gap and not shorting to anything else doesn't usually happen. When I fixed them I cut a piece of brass shim stock the same width as the trace and soldered it in place. A short piece of 30ga wire wrap wire across the gap will work too.

Do you have any idea what you did to blow the ground?

To your original question, the wiring harness provides the electrical ground not the mounting hardware.

 

[rts91tsi]

Definitely a blown ground trace to IC 101, which takes part in the A/D conversion should be connected to that trace at pin 13, and have a continuity path to all of the ECU's ground pins.

If you flip the PCB over you will see where the reference designator for the IC is located, as well as the number 20, which notes the location pin 20 of IC101. Count down from 20 while counting the missing pin as number 18, until you get to pin number 13, then test for continuity between the blown/repaired trace, and all of the ECU's ground pins(17,24,101, and 106).

I made a pin out of the IC by testing for continuity to its pins from the applicable pins of the ECU. That is, if your going to repair it yourself, and would like to also troubleshoot the wired connections from the analog inputs to the IC, just to make sure they are connected correctly to the applicable sensors. Yahoo! Groups

 

[phantom_19]

Thank you all for the posts!!

I thought of something that might have blown it. I have 2 wires going to the ECT from pin 20 and pin 24.
Does it matter to which of the 2 connectors I connect the wires from the ECU? The thing that was holding the 2 wires to connect to the ECT sensor got crispy and it broke.

Ok I found a thread where some wisemen explain that it shouldnt matter which spade connectors go where.
Here is for reference http://www.dsmtuners.com/forums/newbie-forum/323007-coolant-temp-sensor-question.html