knochgoon24
DSM Wiseman
- 6,135
- 92
- Jan 29, 2008
-
Troy,
Michigan
I guess my question is, what can cause the ECU to not have power, or to not turn on when starting the car? Can those with experience check my plan below? As long as we don't get too much rain tomorrow, I plan to run through this list to troubleshoot.
It's been a while, but I'm starting to get back into the DSM game.
Picked up a 91 Talon 2.0 NT (absolute base model) last night with a no-start issue.
I've traced it back to the ECU not getting power... and then it got too dark out to work further. The MPI relay checks out all right. I also have power on fuse #19. Pulling that fuse kills the interior lights.
This is what I have so far:
Step 1:
-Check for 12v on ECU pin 103 at all times. This is ECU backup power from fuse 19.
(If there is no power here, it's a broken wire between fuse 19 and the ECU.)
Step 2:
- Check for 12v on ECU pin 110 when Ignition Switch turned to RUN.
(Power come from Ignition Switch pin 4. Can check for this power by checking for power to fuses 11, 12, and/or 18.)
Step 3:
- At this point, ECU pin 63 should get pulled low, pulling MPI pin 8 to ground, closing that circuit.
(If not, check ECU grounds. ECU pins 101, 104 (MT), 106, are to ground. If those have ground and still no go, then ECU is bad. -- Try grounding MPI pin 8 to see if ECU boots. --> Confirms ECU bad.)
Step 4:
- Now there should be 12v on ECU pin 107 from MPI pin 4, and ECU pin 102 from MPI pin 5.
(MPI relay bench tested fine, so this shouldn't be an issue.)
Step 5:
-When ECU boots, CEL should light for 4 seconds, or stay on if CEL is present.
Other notes:
-When ignition switch is turned to START, ECU pin 108 should see 12v from ignition switch.
- ECU pin 56 controls MPI pin 7.
- ECU pin 64 is the "check engine light" output, in case the bulb is just blown out. This pin gets pulled to ground.
- Pins 17 and 24 are sensor grounds.
It's been a while, but I'm starting to get back into the DSM game.
Picked up a 91 Talon 2.0 NT (absolute base model) last night with a no-start issue.
I've traced it back to the ECU not getting power... and then it got too dark out to work further. The MPI relay checks out all right. I also have power on fuse #19. Pulling that fuse kills the interior lights.
This is what I have so far:
Step 1:
-Check for 12v on ECU pin 103 at all times. This is ECU backup power from fuse 19.
(If there is no power here, it's a broken wire between fuse 19 and the ECU.)
Step 2:
- Check for 12v on ECU pin 110 when Ignition Switch turned to RUN.
(Power come from Ignition Switch pin 4. Can check for this power by checking for power to fuses 11, 12, and/or 18.)
Step 3:
- At this point, ECU pin 63 should get pulled low, pulling MPI pin 8 to ground, closing that circuit.
(If not, check ECU grounds. ECU pins 101, 104 (MT), 106, are to ground. If those have ground and still no go, then ECU is bad. -- Try grounding MPI pin 8 to see if ECU boots. --> Confirms ECU bad.)
Step 4:
- Now there should be 12v on ECU pin 107 from MPI pin 4, and ECU pin 102 from MPI pin 5.
(MPI relay bench tested fine, so this shouldn't be an issue.)
Step 5:
-When ECU boots, CEL should light for 4 seconds, or stay on if CEL is present.
Other notes:
-When ignition switch is turned to START, ECU pin 108 should see 12v from ignition switch.
- ECU pin 56 controls MPI pin 7.
- ECU pin 64 is the "check engine light" output, in case the bulb is just blown out. This pin gets pulled to ground.
- Pins 17 and 24 are sensor grounds.