No power to ECU

swaiteswaite New Wagonist
in Electronics, Fueling & Air Conditioning
So here's what I know: I'm not getting power to the ECU. No CEL when ignition turned on, and no LED. Main relay checks good, but I'm not getting enough power to it for it to click over. When I check the main relay harness at pin 1 (Y/W) and pin 2 (Bl) I get 11 VDC (good or bad?), pin 5 (Y/Bl) to pin 2 (Bl) I get 5 vdc (definitely bad), but when I hook up the black lead to a different ground I get 11 VDC. I'm thinking bad ground on the harness? I think the diagram says it's at C-138 but I have no idea where that's at.
Any help?! Joe (evol911) and I just got the new motor in yesterday and it doesn't start! Major bummer.

Comments

  • Old SkoolOld Skool Council Member
    check your engine grounds.. most likely the cause.. the ecu is tied to the engine for common ground.
  • swaiteswaite New Wagonist
    Care to elaborate?
  • bam-bambam-bam Council Member
    Biggest junction is at the thermostat housing. All the harness grounds terminate there, BUT...

    Our cars use the engine block as an integral part of the ground circuit(as most do). Even if you're cleanly connected to the engine, if that engine isn't bonded to the negative side of the battery- no joy.
    Grounds:
    1) battery neg. to frame apron AND then to transmission
    2) core support to cylinder head and valve cover
    3) main grounds at thermostat housing (tip: bolt wires to the HOUSING, not the cover/water neck. I've seen gasket sealants cause goofy readings)
  • udubrx7udubrx7 Senior Wagonist
    What Bam said!

    Other than that you can look in the manual and it will show all the grounds in the wiring diagrams, probably not a bad idea to check the big ones that are easy to find.
  • swaiteswaite New Wagonist
    It was the thermostat housing ground. Motor started but now I have bigger problems. Idling at 2500 rpm and smoke started billowing out of the valve cover after about 1 minute of engine running. Code 19 on ECU.
  • bam-bambam-bam Council Member
    19?
    You're sure it's not 10, 9 ?

    Did you just do mpfi swap?
  • swaiteswaite New Wagonist
    Yes, 19. No swap.
  • udubrx7udubrx7 Senior Wagonist
    I'm 99% sure code 19 is the automatic transmission lockup solenoid. Is the car an auto? Did you just convert it from auto to manual? Did you change the ECU?

    And how much smoke is coming from the valve cover? I'm assuming it's coming out of the breather hole? Try unplugging the EACV and adjusting the idle with the idle screw to get it closer to where you want it, or at least closer to where you can try and figure out what your other problems are. If there is A LOT of smoke coming out, you should probably do a compression test because you may be getting a large amount of blow-by (combustion sneaking past piston rings).
  • swaiteswaite New Wagonist
    Car is auto. ECU is a PM5, not the one that came with the car.
  • udubrx7udubrx7 Senior Wagonist
    check my last post I just edited it....

    You need to check out your auto lockup solenoid. IIRC it's located kind of on the top front side of the transmission, next to the backup light switch. I don't know how it hooks up, but you should check the wiring.
  • swaiteswaite New Wagonist
    Blow by is what I was scared of. It's quite a bit that comes out of the entire cover. I didn't really get a good luck because I only let it run for a few seconds before I turned it off.
  • udubrx7udubrx7 Senior Wagonist
    Yeh if it's the whole cover that is bad...... got a compression tester? :?
  • swaiteswaite New Wagonist
    Yeah I do. Time to test.
  • swaiteswaite New Wagonist
    150psi on 1. Unable to test other three because battery was starting to get drained. Time for a new thread.
  • swaiteswaite New Wagonist
    Compression good on all cylinders. Smoke is not coming from valve cover, but appears to be coming from where the downpipe and manifold connect.
    I can only get the idle down to about 1500 when the screw stops.
  • udubrx7udubrx7 Senior Wagonist
    The same kind of smoke is coming out of the tailpipe too I assume? What color is it?

    I would check for vacuum leaks and replace the PCV valve (it's like $3).
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