Hello everyone,
I'm having a set of very weird symptoms that I didn't really find a lot of info on the internet, I'm trying to see if there's any electric and/or electronic experts here that could help me out.
I think my ECU is fried, but I don't know how or why, and I want to make sure it's safe to replace it before I do.
Symptom #1:
Upon turning the key to the on position, the KOEO codes begin flashing, and upon starting the car, the KOER test begins. The problem is, the STI connector is not jumped to the SIGRTN port on the adjacent data link connector. I can't turn it off.
Symptom #2:
MIL/CEL randomly flashes during driving, before the period where it would turn on to continuously glow, as it usually should. However, I didn't see any rpm drop or hear any noise that could be attributed to a misfire when it happens. This also occurs for the O/D light, but is not synchronized with the MIL/CEL light.
Symptom #3:
I'm getting a code 543 for the fuel pump control circuit not supplying power to the pump. Thing is, the car can start, run and drive just fine and there are no codes 556 or 557. It does occasionally drop rpm (once, some time after start) before returning to normal for the rest of the drive (be it 15min or 2hrs long), which could be attributed to fuel pump randomly losing contact, but it hasn't stalled once.
Symptom #4:
I'm getting codes 172, 173 and 176, though those could simply be old and slow O2 sensors.
The only other code is 332, but that's probably due to the TAB and TAD being deleted by the previous owner.
As for the first symptom, I have traced it to a series of what I think to be shorts within the ECU. I've took the ECU out of the car and performed these measurements on my desk, with it entirely disconnected.
I've measured the resistance between the following pins:
This leads me to believe:
Furthermore, there is no visible or discernible damage on the connector, it's pins, the board, or the places where the pins are connected to the board, which brings me to my question.
Question:
What could be the possible cause of this damage? Could high voltage from a defective sensor or harness burn through the isolation on the board?
Could corrosion happen on the inside of the board and connect these pins, even though there is no visible corrosion on the outside, or on the leads going into the board from the back of the connector? The board is translucent, and when shining a light through the part where the leads meet the board (on the inside side of the connector) I see no deformities or impurities in the plastic that look like corrosion.
What other causes could be out there? Could this just be regular wear and tear?
I want to make sure before I put in a new ECU that it's not going to get damaged as well.
I'm having a set of very weird symptoms that I didn't really find a lot of info on the internet, I'm trying to see if there's any electric and/or electronic experts here that could help me out.
I think my ECU is fried, but I don't know how or why, and I want to make sure it's safe to replace it before I do.
Symptom #1:
Upon turning the key to the on position, the KOEO codes begin flashing, and upon starting the car, the KOER test begins. The problem is, the STI connector is not jumped to the SIGRTN port on the adjacent data link connector. I can't turn it off.
Symptom #2:
MIL/CEL randomly flashes during driving, before the period where it would turn on to continuously glow, as it usually should. However, I didn't see any rpm drop or hear any noise that could be attributed to a misfire when it happens. This also occurs for the O/D light, but is not synchronized with the MIL/CEL light.
Symptom #3:
I'm getting a code 543 for the fuel pump control circuit not supplying power to the pump. Thing is, the car can start, run and drive just fine and there are no codes 556 or 557. It does occasionally drop rpm (once, some time after start) before returning to normal for the rest of the drive (be it 15min or 2hrs long), which could be attributed to fuel pump randomly losing contact, but it hasn't stalled once.
Symptom #4:
I'm getting codes 172, 173 and 176, though those could simply be old and slow O2 sensors.
The only other code is 332, but that's probably due to the TAB and TAD being deleted by the previous owner.
As for the first symptom, I have traced it to a series of what I think to be shorts within the ECU. I've took the ECU out of the car and performed these measurements on my desk, with it entirely disconnected.
I've measured the resistance between the following pins:
46 (SIGRTN) and 48 (STI): 4k ohms
46 (SIGRTN) and 17 (MIL/CEL): 4k ohms
46 (SIGRTN) and 26 (VREF): 670 ohms
8 (Fuel pump power check pin) and 26 (VREF): 6k ohms
8 (Fuel pump power check pin) and 46 (SIGRTN): 5k ohms
Many other pins near and around 26 (VREF) have around 22k ohms between each other
This leads me to believe:
A) The 4k ohms is enough to start KOER and KOEO tests
B) MIL/CEL is shorted to at least one pin it's not supposed to short to (in this case STI)
C) SIGRTN is shorted to VREF
D) Pins at and around VREF are either corroded or the isolation between them is burnt through to cause these connections.
E) Symptoms 1, 2 and 3 are all caused by these shorts
Furthermore, there is no visible or discernible damage on the connector, it's pins, the board, or the places where the pins are connected to the board, which brings me to my question.
Question:
What could be the possible cause of this damage? Could high voltage from a defective sensor or harness burn through the isolation on the board?
Could corrosion happen on the inside of the board and connect these pins, even though there is no visible corrosion on the outside, or on the leads going into the board from the back of the connector? The board is translucent, and when shining a light through the part where the leads meet the board (on the inside side of the connector) I see no deformities or impurities in the plastic that look like corrosion.
What other causes could be out there? Could this just be regular wear and tear?
I want to make sure before I put in a new ECU that it's not going to get damaged as well.